@article {JRN55318, title = {Ecological theory and practice in arid and semiarid ecosystems: a tale of two LTER sites}, volume = {59}, year = {2021}, pages = {151-180}, publisher = {Archimedes (New Studies in the History and Philosophy of Science and Technology)}, abstract = {The chapter compares the conceptual history of two Long Term Ecological Research (LTER) programs at U.S. Department of Agriculture (USDA) research sites established following land overuse in the early 1900s. Early USDA studies were based on a Clementsian model, where vegetation following disturbance was expected to return to the climax determined by climate and soils. Management-based alternatives to the Clementsian model were developed after the dominant vegetation failed to recover and alternative states were observed. The Central Plains Experimental Range LTER (later Shortgrass Steppe LTER) program began in 1981 at a site in northern Colorado. Early studies focused on the inability of the dominant species, blue grama (Bouteloua gracilis), to recover on long-abandoned agricultural fields. These observations were in contrast to the resilience of blue grama-dominated ecosystems in response to livestock grazing and drought. The Jornada Basin LTER program began in 1982 at a Chihuahuan Desert site in southern New Mexico, where black grama-dominated (Bouteloua eriopoda) grasslands converted to shrublands following livestock overgrazing and drought. Early Jornada studies focused on the causes and consequences of this desertification. In collaboration with USDA scientists, the two LTER programs developed new research ideas and approaches which brought an improved understanding of historic dynamics and nuance to the Clementsian-based paradigm. New paradigms also reflected the importance of objective, long-term studies and the dynamic, multi-scale nature of these arid and semiarid ecosystems. Comparing two LTER programs at research sites sharing a conceptual basis, but with different ecosystem properties, can provide insights into the development of US grassland ecology over the past century.}, keywords = {arid ecosystems, desertification, drought, Ecological climax, grassland ecology, International Biological Program, livestock grazing, long-term ecological research, LTER program}, isbn = {978-3-030-66932-4}, doi = {10.1007/978-3-030-66933-1_6}, author = {Debra C. Peters} } @article {JRN55313, title = {Plant species richness in multiyear wet and dry periods in the Chihuahuan Desert}, journal = {Climate}, volume = {9}, year = {2021}, month = {8/13/2021}, pages = {130}, abstract = {In drylands, most studies of extreme precipitation events examine effects of individual years or short-term events, yet multiyear periods (>3 y) are expected to have larger impacts on ecosystem dynamics. Our goal was to take advantage of a sequence of multiple long-term (4-y) periods (dry, wet, average) that occurred naturally within a 26-y time frame to examine responses of plant species richness to extreme rainfall in grasslands and shrublands of the Chihuahuan Desert. Our hypothesis was that richness would be related to rainfall amount, and similar in periods with similar amounts of rainfall. Breakpoint analyses of water-year precipitation showed five sequential periods (1993{\textendash}2018): AVG1 (mean = 22 cm/y), DRY1 (mean = 18 cm/y), WET (mean = 30 cm/y), DRY2 (mean = 18 cm/y), and AVG2 (mean = 24 cm/y). Detailed analyses revealed changes in daily and seasonal metrics of precipitation over the course of the study: the amount of nongrowing season precipitation decreased since 1993, and summer growing season precipitation increased through time with a corresponding increase in frequency of extreme rainfall events. This increase in summer rainfall could explain the general loss in C3 species after the wet period at most locations through time. Total species richness in the wet period was among the highest in the five periods, with the deepest average storm depth in the summer and the fewest long duration (>45 day) dry intervals across all seasons. For other species-ecosystem combinations, two richness patterns were observed. Compared to AVG2, AVG1 had lower water-year precipitation yet more C3 species in upland grasslands, creosotebush, and mesquite shrublands, and more C4 perennial grasses in tarbush shrublands. AVG1 also had larger amounts of rainfall and more large storms in fall and spring with higher mean depths of storm and lower mean dry-day interval compared with AVG2. While DRY1 and DRY2 had the same amount of precipitation, DRY2 had more C4 species than DRY1 in creosote bush shrublands, and DRY1 had more C3 species than DRY2 in upland grasslands. Most differences in rainfall between these periods occurred in the summer. Legacy effects were observed for C3 species in upland grasslands where no significant change in richness occurred from DRY1 to WET compared with a 41\% loss of species from the WET to DRY2 period. The opposite asymmetry pattern was found for C4 subdominant species in creosote bush and mesquite shrublands, where an increase in richness occurred from DRY1 to WET followed by no change in richness from WET to DRY2. Our results show that understanding plant biodiversity of Chihuahuan Desert landscapes as precipitation continues to change will require daily and seasonal metrics of rainfall within a wet-dry period paradigm, as well as a consideration of species traits (photosynthetic pathways, lifespan, morphologies). Understanding these relationships can provide insights into predicting species-level dynamics in drylands under a changing climate.}, keywords = {climate change; extreme events; breakpoint analysis; Chihuahuan Desert; black grama grasslands; mesquite shrublands; precipitation characteristics; multiyear periods; legacies}, doi = {10.3390/cli9080130}, url = {files/bibliography/21-030.pdf}, author = {Debra C. Peters and Heather Savoy and Susan Stillman and Haitao Huang and Amy R. Hudson and O. E. Sala and Enrique Vivoni} } @article {JRN55307, title = {AI recommender system with ML for agricultural research}, journal = {IEEE IT Professional}, volume = {22}, year = {2020}, month = {05/01/2020}, pages = {29-32}, abstract = {We describe an AI recommender system (RS) with machine learning to harness past user choices and large volumes of data, yet account for changes in weather and management decisions characteristic of agricultural systems. Our goal is to maximize the use of data relevant to solving agricultural problems and improve the efficiency of the scientific workforce while also improving the accuracy of estimates of the amount of food produced. Our example shows how the RS learns data analysis choices from user behavior for predicting agricultural production responses to rainfall and learns to identify classes of agroecosystem responses to alternative climate scenarios. We account for changes in relationships using spatial and temporal statistics. The RS provides a powerful approach to make use of the large amounts of data and scientific expertise in the agricultural enterprise to predict agroecosystem dynamics under changing environmental conditions.}, doi = {10.1109/MITP.2020.2986125}, url = {files/bibliography/20-037.pdf}, author = {Debra C. Peters and Heather Savoy and Geovany Ramirez and C. Huang} } @article {JRN55215, title = {Big data-model integration and AI for vector-borne disease predictor}, journal = {Ecosphere}, volume = {11}, year = {2020}, month = {06/2020}, pages = {1-20}, chapter = {1}, abstract = {Predicting the drivers of incursion and expansion of vector-borne diseases as part of early-warning strategies (EWS) is a major challenge for geographically extensive diseases where spread is mediated by spatial heterogeneity in climate and other environmental drivers. Geospatial data on these environmental drivers are increasingly available affording opportunities for application to a predictive disease ecology paradigm provided the data can be synthesized and harmonized with fine-scale, highly resolved data on vector and host responses to their environment. Here, we apply a multi-scale big data{\textendash}model integration approach using human-guided machine learning to objectively evaluate the importance of a large suite of spatially distributed environmental variables (>400) to develop EWS for vesicular stomatitis (VS), a common viral vectorborne vesicular disease affecting livestock throughout the Americas. Two temporally and phylogenetically distinct events were used to develop disease occurrence{\textendash}environment relationships in incursion (2004) and expansion years (2005), and then to test those relationships (2014, 2015) at two scales: (1) local and (2) landscape to regional. Our results show that VS occurrence at a local scale of individual landowners was related to conditions that can be monitored (rainfall, temperatures, streamflow) or modified (vegetation). On-site green vegetation during the month of occurrence and higher rainfall four months prior combined with either cool daytime (expansion) or nighttime (incursion) temperatures one month prior were indicators of VS occurrence. Distance to running water (incursion) and host density based on neighboring ranches (expansion) with infected animals were also important in individual years. At landscape-to-regional scales, conditions that favor specific VSV biological vectors were indicated, either black flies in incursion years or biting midges in expansion years. Changes in viral genetic lineage were less important to patterns in VS occurrence than factors affecting the host{\textendash}vector{\textendash}environment interactions. In combination with our onset map based on latitude, elevation, and long-term annual precipitation, this year- and scale-specific information can be used to develop strategies to minimize effects of future VS events. This big data approach coupled with expert knowledge and machine learning can be applied to other emerging diseases for improvement in understanding, prediction, and management of vector-borne diseases.}, keywords = {artificial intelligence, continental scale, expert knowledge, insect vectors, livestock, phylogeography, regional scale, RNA virus, vesicular stomatitis virus}, doi = {https://doi.org/10.1002/ecs2.3157}, url = {files/bibliography/20-024.pdf}, author = {Debra C. Peters and David McVey and Emile H. Elias and Angela Pelzel-McCluskey and J. D. Derner and N. Dylan Burruss and Scott T. Schrader and Jin Yao and Steven J. Pauszek and Lombard, Jason and Luis L Rodriguez} } @article {JRN55198, title = {Deciphering the past to inform the future: preparing for the next ({\textquotedblleft}really big{\textquotedblright}) extreme event}, journal = {Frontiers in Ecology and the Environment}, year = {2020}, month = {04/2020}, pages = {10.1002/fee.2194}, abstract = {

Climate change will bring more extremes in temperature and precipitation that will impact productivity and ecosystem resilience throughout agroecosystems worldwide. Historical events can be used to identify drivers that impact future events. A\  catastrophic drought in the US in the 1930s resulted in an abrupt boundary between areas severely impacted by the Dust Bowl and areas that were less severely affected. Historical primary production data confirmed the location of this boundary at the border between two\ states (Nebraska and Iowa). Local drivers of weather and soils explained production responses across the boundary before and after the drought (1926{\textendash}1948). During the drought, however, features at the landscape scale (soil properties and wind velocities) and regional scale (the Missouri River, its floodplain, and the nearby Loess Hills) explained most of the observed variance in primary production. The impact of future extreme events may be affected by land surface properties that either accentuate or ameliorate the effects of these events. Consideration of large-scale geomorphic processes may be necessary to interpret and manage for catastrophic events.

}, keywords = {agroecosystems, climate change, dust, dust bowl, future, historical, large-scale, regional-scale}, doi = {10.1002/fee.2194}, url = {bibliography/20-010.pdf}, author = {Debra C. Peters and N. Dylan Burruss and Gregory S. Okin and J. Hatfield and Stacey L P Scroggs and Haitao Huang and Colby Brungard and Jin Yao} } @article {JRN55308, title = {Harnessing AI to transform agriculture and inform agricultural research}, journal = {IEEE IT Professional}, volume = {22}, year = {2020}, month = {05/01/2020}, pages = { 16 - 21}, abstract = {We provide an overview of the Special Issue on current advances, challenges, and opportunities for AI technologies in agriculture. We illustrate the potential of AI using four major components of the food system: production, distribution, consumption, and uncertainty. We recognize that the transformation of agriculture will require new tools to more precisely manage fields to increase production while minimizing the environmental risk to water and air quality. Combining AI with other technologies will be needed to provide effective production management strategies for a given combination of soil, climate, pest complexes, and vegetation. New methods will be needed to determine production limitations, and effective management options. The agricultural enterprise is prime for the use of AI and other technologies if they can be adapted for the unique characteristics of agroecosystems, including variability and directional changes in climate and other global change drivers as well as novel management and policy decisions, and economic market volatility.}, keywords = {agriculture, artificial intelligence, Immune system, meteorology, production, Uncertainty}, doi = {10.1109/MITP.2020.2986124}, url = {files/bibliography/20-038.pdf}, author = {Debra C. Peters and Adam Rivers and J. Hatfield and Danielle G. Lemay and Simon Liu and Bruno Basso} } @conference {JRN55245, title = {Harnessing the power of AI technologies for ecology: The knowledge learning analysis system (KLAS) for spatially-distributed, continuous ecological data}, booktitle = {Ecological Society of America}, year = {2020}, month = {08/2020}, address = {Virtual Conference}, abstract = {Background/Question/Methods Sensors are increasingly being used to capture information about biotic processes and environmental conditions at finer spatial and temporal resolutions across broader spatial extents than possible from data collected manually. This sensor-based information is leading to new insights about ecological systems through the integration of data across scales, disciplinary interests, and levels of organization. However, sensors can also produce large volumes of different types of data at higher frequencies for more spatially-distributed locations than ecologists are used to handling or managing. Artificial intelligence (AI) technologies provide one approach to effectively distilling, managing, and analyzing these large and diverse amounts of data to be used for ecological problems. Our objectives were to develop an AI system to evaluate and learn from streaming data that: (1) would automate the QA/QC of sensor data, and (2) would be sufficiently flexible to account for changes in climate through time. We developed an AI system in R and MatLab combined with the GCE Toolbox. We analyzed sensor data from 15 meteorological stations spatially-distributed at the Jornada USDA-LTER site in southern New Mexico. We then tested the scalability of our AI system by applying it to an additional 60 spatially-distributed meteorological stations locations at the Jornada, and to primary production data. Results/Conclusions; Our AI system effectively assimilated and analyzed large volumes of streaming data from meteorological stations, and provided level one QA/QC data for all 15 locations. The data were uploaded to a national data repository (EDI) with ecological metadata within one day following data collection. These metrics contrast with our previous manual approach to checking and correcting the data that resulted in monthly time lags before uploading the data. The AI system was successfully applied to an additional 60 locations with meteorological stations, and to primary production data. Given the automated data collection and AI computational process, adding more stations did not increase the time required for checking and uploading the data to EDI, and the errors associated with the data did not increase. Recent additions to our approach to identifying outliers from extreme values based on comparisons with nearby locations result in an approach that is sufficiently flexible to account for changes in climate through time. Our AI system is a dynamic approach that can be applied to other data types, locations, and ecosystems where non-stationarity through time is important. Poster $\#$85379.}, author = {Debra C. Peters and Geovany Ramirez and John P. Anderson and Heather Savoy and Haitao Huang} } @article {JRN55290, title = {Modifying connectivity to promote state change reversal: the importance of geomorphic context and plant{\textendash}soil feedbacks}, journal = {Ecology}, volume = {101}, year = {2020}, month = {4/16/2020}, pages = {e03069}, abstract = {Alternative states maintained by feedbacks are notoriously difficult, if not impossible, to reverse. Although positive interactions that modify soil conditions may have the greatest potential to alter self-reinforcing feedbacks, the conditions leading to these state change reversals have not been resolved. In a 9-yr study, we modified horizontal connectivity of resources by wind or water on different geomorphic surfaces in an attempt to alter plant{\textendash}soil feedbacks and shift woody-plant-dominated states back toward perennial grass dominance. Modifying connectivity resulted in an increase in litter cover regardless of the vector of transport (wind, water) followed by an increase in perennial grass cover 2 yr later. Modifying connectivity was most effective on sandy soils where wind is the dominant vector, and least effective on gravelly soils on stable surfaces with low sediment movement by water. We found that grass cover was related to precipitation in the first 5 yr of our study, and plant{\textendash}soil feedbacks developed following 6 yr of modified connectivity to overwhelm effects of precipitation on sandy, wind-blown soils. These feedbacks persisted through time under variable annual rainfall. On alluvial soils, either plant{\textendash}soil feedbacks developed after 7 yr that were not persistent (active soils) or did not develop (stable soils). This novel approach has application to drylands globally where desertified lands have suffered losses in ecosystem services, and to other ecosystems where connectivity-mediated feedbacks modified at fine scales can be expected to impact plant recovery and state change reversals at larger scales, in particular for wind-impacted sites.}, keywords = {aeolian processes, alternative states, cusp-catastrophe model, desertification, ecohydrology, long-term studies, regime shifts remediation}, doi = {10.1002/ecy.3069}, url = {files/bibliography/20-035.pdf}, author = {Debra C. Peters and Gregory S. Okin and Jeffrey E. Herrick and Heather Savoy and John P. Anderson and Stacey L P Scroggs and J. Zhang} } @conference {JRN54909, title = {Can connectivity-mediated feedbacks to vegetation explain surprising ecological responses to catastrophic events?}, booktitle = {Ecological Society of America}, year = {2018}, month = {08/2018}, publisher = {Ecological Society of America}, organization = {Ecological Society of America}, address = {New Orleans, LA}, abstract = {

Multi-year extreme drought events that affect regional to sub-continental extents have catastrophic impacts on ecological systems. Drought impacts are often studied based on local factors, such as climate and soils, interacting with local ecological processes (e.g., competition between plants). However, spatial processes operating within broad extents can lead to connectivity-mediated feedbacks to the vegetation that overwhelm direct effects of drought and lead to unexpected landscape-scale heterogeneity. One of the most devastating droughts occurred in the Great Plains of North America in the 1930s. This climatic event combined with land management practices (plowing and subsequent abandonment) to result in broad-scale plant mortality, soil erosion, and dust storms. However, not all areas were affected similarly, even across short distances. We hypothesized that spatial discontinuities in impacts were related to: (1) local factors of climate, soil properties, and management and/or (2) connectivity by wind and/or water erosion from nearby locations. We integrated legacy data from the U.S. Department of Agriculture on production, management, and erosion with climatic and edaphic data (1920s to 1940s) for a 100-km gradient from western Iowa to eastern Nebraska. Responses were compared during the drought to responses for the same location in the 1920s (pre-drought) and the 1940s (post-drought). Our results show complex interactions among precipitation, temperature, soil properties, and management practices across this relatively short (100-km) gradient. Climatic drivers tended to be more important to production in the more mesic part of the gradient (IA), and soil properties became more important as precipitation decreased to the west (NE). However, local factors alone were unable to explain lower production in NE than IA for locations with similar properties. Landscape features, such as large alluvial plains that reduced connectivity by wind, were more important than local factors to explain different responses along the gradient during the drought. These findings have important implications for landscape configurations and connectivity in the face of large-scale, extreme events.

}, author = {Debra C. Peters and N. Dylan Burruss and Gregory S. Okin and J. Hatfield and Colby Brungard} } @conference {JRN54940, title = {Developing an integrated knowledge landscape map using a trans-disciplinary approach}, booktitle = {LTER All Scientists Meeting}, year = {2018}, month = {10/2018}, address = {Pacific Grove, California}, abstract = {

Our goal is to develop an operational trans-disciplinary approach to complex landscapes that facilitates integration of large and diverse types of data and knowledge to: (1) reduce the high spatial heterogeneity in sampling across heterogeneous landscapes and fill data/knowledge gaps for underrepresented locations; (2) characterize the non-stationarity of environmental drivers and ascertain the extent to which knowledge of the past can, or cannot, inform the future; and (3) inform land managers and others in prioritizing locations. We illustrate the utility of our approach to extend process-based understanding of ANPP at intensively studied locations to dynamics of ANPP at other under-represented locations, and to predict spatial variability in ANPP across the landscape.

}, author = {Debra C. Peters and Brandon T Bestelmeyer and Gregory S. Okin and O. E. Sala and Enrique Vivoni and Steven R. Archer and Colby Brungard and Jeffrey E. Herrick and Niall Hanan} } @conference {JRN54936, title = {Harnessing the power of big data in ecology by machine learning}, booktitle = {10th Internationl Conference on Ecological Informatics}, year = {2018}, month = {09/2018}, address = {Jena, Germany}, abstract = {

My talk will be about a Trans-Disciplinary Data-Model Integration (TDMI) approach that focuses on spatio-temporal modeling and cross-scale interactions, and employs interactive machine learning strategies. Applied to ecological problems, my approach integrates knowledge and data on: (1) biological processes, (2) spatial heterogeneity in the land surface template, and (3) variability in environmental drivers using data and knowledge drawn from multiple lines of evidence (i.e., observations, experimental manipulations, analytical and numerical models, products from imagery, conceptual model reasoning, theory). I will apply this approach to a suite of increasingly complex ecologically-relevant problems, and will show how the framework can be linked with a Data Science Integration System (DSIS) to allow more complex questions to be addressed in the future.

}, author = {Debra C. Peters} } @conference {JRN54938, title = {Insights from Long-Term Ecological Research: free EcoTrends books available}, year = {2018}, month = {10/2018}, address = {Pacfic Grove, California}, abstract = {

EcoTrends is a project to synthesize long-term data to examine trends in the Earth{\textquoteright}s ecosystems. Participants in the data synthesis included scientists and information managers from 50 sites, including 25 LTER sites. The large and diverse collection of long-term ecological datasets can be found through the EcoTrends website (https://ecotrends.info/) or through our book (Peters et al. 2013), Our Changing World: Insights from Long-Term Ecological Research. This book is an excellent compendium of long-term ecological data and trends from long-term research sites.\  We have a small number of complimentary copies of our book available, and interested persons may sign up to have a free copy shipped to them.

}, author = {Debra C. Peters} } @article {JRN54926, title = {An integrated View of Complex Landscapes: A Big Data-Model Integration Approach to Transdisciplinary Science}, journal = {Bioscience}, volume = {68}, year = {2018}, month = {09/2018}, pages = {653-669}, chapter = {653}, abstract = {

The Earth is a complex system comprising many interacting spatial and temporal scales. We developed a transdisciplinary data-model integration (TDMI) approach to understand, predict, and manage for these complex dynamics that focuses on spatiotemporal modeling and cross-scale interactions. Our approach employs human-centered machine-learning strategies supported by a data science integration system (DSIS). Applied to ecological problems, our approach integrates knowledge and data on (a) biological processes, (b) spatial heterogeneity in the land surface template, and (c) variability in environmental drivers using data and knowledge drawn from multiple lines of evidence (i.e., observations, experimental manipulations, analytical and numerical models, products from imagery, conceptual model reasoning, and theory). We apply this transdisciplinary approach to a suite of increasingly complex ecologically relevant problems and then discuss how information management systems will need to evolve into DSIS to allow other transdisciplinary questions to be addressed in the future.

}, keywords = {cross-scale interactions, data science, earth science, landscape ecology, machine learning}, doi = {doi:10.1093/biosci/biy069}, url = {files/bibliography/18-015.pdf}, author = {Debra C. Peters and N. Dylan Burruss and Luis L Rodriguez and David McVey and Emile H. Elias and Angela Pelzel-McCluskey and J. D. Derner and Scott T. Schrader and Jin Yao and Steven J. Pauszek and Lombard, Jason and Steven R. Archer and Dawn M. Browning and Colby Brungard and J. Hatfield and Niall Hanan and Jeffrey E. Herrick and Gregory S. Okin and O. E. Sala and Heather Savoy and Enrique Vivoni and Brandon T Bestelmeyer} } @conference {JRN54939, title = {Long-Term Research at the Jornada Basin (LTER VII)}, booktitle = {LTER All Scientists Meeting 2018}, year = {2018}, month = {10/2018}, address = {Pacific Grove, California}, abstract = {

Chihuahuan Desert landscapes exemplify the ecological conditions, vulnerability, and management challenges in arid and semi-arid regions around the world. The goal of the Jornada Basin Long Term Ecological Research program (JRN LTER) is to understand and quantify the key factors and processes controlling ecosystem dynamics in Chihuahuan Desert landscapes. In LTER-VII, we explore how spatial heterogeneity of dryland ecosystems evolves over time in response to disturbance triggers, positive feedbacks, and their interactions with the eco-geomorphic template.\  Our recent observations indicate the need to conceptually and computationally integrate data and knowledge into a Data Science Integrated System (DSIS).

}, author = {Debra C. Peters and Niall Hanan and Brandon T Bestelmeyer and Gregory S. Okin and O. E. Sala and Robert L. Schooley and Steven R. Archer and Stephanie Bestelmeyer and Colby Brungard and Ferran Garcia-Pichel and Jeffrey E. Herrick and Curtis H. Monger and Pietrasiak, Nicole and Craig Tweedie} } @article {JRN54775, title = {A toolkit for ecosystems ecologists in the time of big science}, journal = {Ecosystems}, volume = {20}, year = {2017}, month = {03/2017}, pages = {259-266}, chapter = {259}, abstract = {

Ecosystems ecologists are being challenged to address the increasingly complex problems that comprise Big Science. These problems include multiple levels of biological organization that cross multiple interacting temporal and spatial scales, from individual plants, animals and microbes to landscapes, continents, and the globe. As technology improves, the availability of data, derived data products, and information to address these complex problems are increasing at finer and coarser scales of resolution, and legacy {\textquotedblleft}dark data{\textquotedblright} are being brought to light. \ Data analytics are improving as {\textquotedblleft}big{\textquotedblright} data increase in importance in other fields that are improving access to these data. \ New data sources (crowd sourcing, social media), and ease of communication and collaboration among ecosystems ecologists and other disciplines are increasingly possible via the internet. It is increasingly important that ecosystems ecologists be able to communicate their findings, and to translate their concepts and findings into concrete {\textquotedblleft}bits{\textquotedblright} of information that a general public can understand. Traditional approaches that portray ecosystem sciences as a dichotomy between empirical research and theoretical research will keep the field from fully contributing to the complexity of global change questions, and will keep ecosystems ecologists from taking full advantage of the data and technology available. Building on previous research, we describe a more forward-looking, integrated empirical-theoretical-modeling approach that is iterative with learning to take advantage of the elements of Big Science. We suggest that training ecosystems ecologists in this integrated approach will be critical to addressing complex Earth system science questions, now and in the future.

}, doi = {10.1007/s10021-016-0072-1}, url = {files/bibliography/16-024.pdf}, author = {Debra C. Peters and Gregory S. Okin} } @conference {JRN54634, title = {Complex landscapes in the American Southwest: Under what conditions does desetification lead to novel ecosystems?}, booktitle = {2016 Ecological Society of America Meetings}, year = {2016}, month = {08/2016}, publisher = {Ecological Society of America Abstracts}, organization = {Ecological Society of America Abstracts}, address = {Ft Lauderdale, FL}, abstract = {
Novel ecosystems are often defined as no-analog communities consisting of new combinations of species that assemble under new abiotic conditions. In the Anthropocene, novel systems differ from the historical state as a result of human influences where self-organizational processes prevail to make these ecosystems unlikely to revert to their historical structure/function. Degraded shrub-dominated ecosystems that develop following livestock overgrazing and drought in arid and semiarid grasslands are a potential example of novel ecosystems. Although the self-organization and stability of desertified ecosystems have been well-studied, these ecosystems have not been tested as novel ecosystems. Our objective was to test novel ecosystem concepts and hypotheses across complex landscapes at a 78,000 ha research site established in 1912 to examine the causes and consequences of desertification. We integrated long-term vegetation maps dating to 1850 with USDA data on grazing, drought, and species composition (1915 onward), and a suite of LTER data on biotic and abiotic patterns and processes (1982-present) for the Jornada Basin LTER-USDA site in southern New Mexico, USA. We hypothesized that degraded ecosystems dominated by different grass-shrub assemblages represent novel ecosystems if they meet each of four criteria: 1. different from past states, 2. human-driven, 3. self-organized, and 4. irreversible.\ 
All four criteria were met for some locations for each degraded shrubland type (mesquite, creosotebush, tarbush), yet not all locations were identified as novel. Because these shrub species are native to the region, an expansion of a species beyond its native habitat is needed for novelty to be recognized. Our synthesis shows that this expansion was initiated by human drivers, but then for some locations a change in soil properties occurred through time that led to a shift in species dominance and composition and further changes in soil properties. These shifts were maintained by plant-soil feedbacks and self-organization to result in novel ecosystems. On other locations, a localized spatial redistribution of soil and nutrients among grasses and shrubs within the ecosystem occurred that led to a state change, but not a novel ecosystem. Thus, arid landscapes are complex mosaics of historic grass remnants, degraded yet native shrublands, and degraded and novel shrublands. The dynamic soil-geomorphic template interacting with species characteristics is another layer of complexity that needs to be accounted for when predicting future dynamics of arid landscapes that contain novel ecosystems.
}, author = {Debra C. Peters and Steven R. Archer and O. E. Sala and Kris Havstad and Enrique Vivoni and Gregory S. Okin} } @conference {JRN54612, title = {Integrating legacy data to understand agroecosystem regional dynamics to catastrophic events}, booktitle = {American Geophysical Union Fall Meeting }, year = {2016}, month = {12/2016}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {
Multi-year extreme drought events are part of the history of the Earth system. Legacy data on the climate drivers, geomorphic features, and agroecosystem responses across a dynamically changing landscape throughout a region can provide important insights to a future where large-scale catastrophic events may occur more frequently. One of the most devastating multi-year droughts occurred in the central grasslands region of North America in the 1930s. This regional-scale climatic event combined with land management practices to result in broad-scale plant mortality and massive dust storms that impacted the entire continent. However, not all areas were affected similarly, even across relatively short distances with similar climate, soils, and land management. Spatial discontinuities in impacts occurred across a 100-km transition from high plant mortality and high rates of soil erosion in eastern Nebraska to areas in western Iowa with reductions in grass cover and biomass, but low rates of plant mortality and erosion. Because this time period preceded modern agriculture and the extensive plowing of native tallgrass prairie, the landscape was composed of both native prairie grassland and cropland. Responses were compared during the drought to responses for the same region in the 1920s (pre-drought) and the 1940s (post-drought). A large number of legacy datasets from the U.S. Department of Agriculture and other sources were spatially integrated to test two hypotheses: (1) local factors of climate and soil properties explained agroecosystem responses in the pre- and post-drought periods, (2) local factors were insufficient to explain agroecosystem responses during the multi-year drought. Analyses supported these hypotheses and found that landscape features, such as large alluvial plains that reduced connectivity by sand and deposition by wind, were more important than local factors to explain different responses along the gradient during the drought. Similar results were found for both native grassland and cropland. These findings have important implications for landscape configurations and connectivity in the face of large-scale, extreme events.\ 
}, author = {Debra C. Peters and N. Dylan Burruss and Jin Yao and Gregory S. Okin and Stacey L P Scroggs and Curtis H. Monger and Kris Havstad} } @article {JRN54598, title = {A toolkit for ecosystem ecologists in the time of Big Science}, journal = {Ecosystems}, year = {2016}, abstract = {

Ecosystem ecologists are being challenged to address the increasingly complex problems that comprise Big Science. These problems include multiple levels of biological organization that cross multiple interacting temporal and spatial scales, from individual plants, animals, and microbes to landscapes, continents, and the globe. As technology improves, the availability of data, derived data products, and information to address these complex problems are increasing at finer and coarser scales of resolution, and legacy, dark data are brought to light. Data analytics are improving as big data increase in importance in other fields that are improving access to these data. New data sources (crowdsourcing, social media) and ease of communication and collaboration among ecosystem ecologists and other disciplines are increasingly possible via the internet. It is increasingly important that ecosystem ecologists be able to communicate their findings, and to translate their concepts and findings into concrete bits of information that a general public can understand. Traditional approaches that portray ecosystem sciences as a dichotomy between empirical research and theoretical research will keep the field from fully contributing to the complexity of global change questions, and will keep ecosystem ecologists from taking full advantage of the data and technology available. Building on previous research, we describe a more forward-looking, integrated empirical{\textendash} theoretical modeling approach that is iterative with learning to take advantage of the elements of Big Science. We suggest that training ecosystem ecologists in this integrated approach will be critical to addressing complex Earth system science questions, now and in the future.

}, keywords = {analytics, big data, crowdsourcing, interacting spatial and temporal scales, machine learning, multiple levels of organization, technological advances}, doi = {10.1007/s10021-016-0072-1}, url = {files/bibliography/JRN00645.pdf}, author = {Debra C. Peters and Gregory S. Okin} } @article {JRN54143, title = {Beyond desertification: new paradigms for dryland landscapes}, journal = {Frontiers in Ecology and the Environment}, volume = {13}, year = {2015}, month = {02/2015}, pages = {4-12}, chapter = {4}, abstract = {

The traditional desertification paradigm focuses on the losses of ecosystem services that typically occur when grasslands transition to systems dominated by bare (unvegetated) ground or by woody plants that are unpalatable to domestic livestock. However, recent studies reveal complex transitions across a range of environmental conditions and socioeconomic contexts. The papers in this Special Issue illustrate how an improved understanding of these dynamics is generating more robust paradigms, where state changes and regime shifts occurring within the context of changes in land use and climate are modified by landform and antecedent conditions. New and emerging technologies are being used to characterize and evaluate processes and outcomes across various scales and levels of organization. At the same time, developments in education are taking advantage of these new perspectives to improve the ecological literacy of future generations, and to better inform land-management decisions. A framework that integrates these perspectives provides a more comprehensive approach for understanding and predicting dryland dynamics.

}, keywords = {desertification, desertification paradigm, dryland landscapes, ecological literacy, ecosystem services, land management, land use, regime shifts, spatial connectivity}, doi = {10.1890/140276}, url = {/files/bibliography/15-001.pdf}, author = {Debra C. Peters and Kris Havstad and Steven R. Archer and O. E. Sala} } @conference {JRN54433, title = {Can we use the past as a lens to the future? Using historic events to predict regional grassland and shrubland responses to multi-year drought or wet periods under climate change}, booktitle = {100th Annual Meeting of the Ecological Society of America}, year = {2015}, month = {08/2015}, address = {Baltimore, MD}, abstract = {

Background/Question/Methods Ecologists are being challenged to predict ecosystem responses under changing climatic conditions. Water availability is the primary driver of ecosystem processes in temperate grasslands and shrublands, but uncertainty in the magnitude and direction of change in precipitation (increase or decrease) at site to regional scales reduces the predictive capacity to determine future trends with robust levels of acceptable risk for land managers. Long-term research networks of sites (LTER, LTAR) provide natural experiments for system responses that occurred historically during multi-year drought or wet periods (\>=4 y) that can be used to make predictions under future climate scenarios. We tested three alternative hypotheses using long-term data (12 to \> 50y) of aboveground net primary production (ANPP) from eight sites in North America where precipitation showed sequences of wet periods, multi-year drought, and no trend years. We hypothesized that ANPP in wet (or drought) periods can be best explained by: (1) long-term relationships between ANPP and precipitation, (2) relationships between ANPP and precipitation in individual wet or dry years, or (3) relationships between ANPP and precipitation in wet or dry periods. We compared regression slopes and r2 values among equations at each site to determine the relationship with the best fit. For most sites across the region, the equation developed using ANPP and precipitation during drought periods was a better predictor of ANPP during drought compared with the long-term equation. In addition, the drought period equation had a steeper slope than the long-term equation. Thus, approaches that use long-term ANPP-precipitation relationships to predict ANPP during multi-year drought will result in over-estimates of ANPP. In contrast, in wet periods at some sites, the number of wet years in a row was a better predictor of ANPP than the amount of precipitation during the wet period. Cumulative processes, including plant-soil water feedbacks, sequential plant population processes, and plant or soil legacies may be operating to influence these temporal dynamics. These equations relating ANPP to precipitation during multi-year drought or number of wet years can be used to explain historic patterns, such as the during the 1930s drought or unusual grass recovery patterns, as well as to improve future predictions under directional climate change.\  Abstract COS 5-5.

}, author = {Debra C. Peters and Jin Yao and N. Dylan Burruss and Kris Havstad and O. E. Sala and J. D. Derner and John Hendrickson and Matt A Sanderson and John M Blair and S.L. Collins} } @article {JRN54211, title = {Ecological challenges posed by climate uncertainty}, year = {2015}, pages = {8}, abstract = {

We{\textquoteright}ve been collecting long-term data at many ecological and agricultural research sites across the United States and globally, in some cases for over 100 years. This means we have a lot of data, and we feel like we understand our ecosystems very well{\textemdash}up until the climate drivers start changing beyond the range of historic variability. These changes make us nervous because they cause the rules between the physical drivers and the biota to change{\textemdash}and, in particular, during extreme events, including heat waves, freezes, floods, and droughts. It{\textquoteright}s very difficult for ecologists to deal with extreme events because we need long-term data to observe and understand events that rarely occur. Take something that occurs very infrequently, such as the Florida citrus freeze: How do we study that? How do we prepare for that? The other aspect of these events deals with space. A lot of ecological studies are small-plot studies, at a scale as small as a meter square in grasslands and up to a hectare in forests. You can imagine those plots don{\textquoteright}t represent very much area, and we have to do replications in order to understand these problems really well. What we really need to know is how to extrapolate these small-plot dynamics spatially so we can predict how large landscapes will respond to climate change. These large landscapes are difficult, if not impossible, to replicate. Propagating events{\textemdash}such as wildfires or species invasions{\textemdash}come into play when we put space and time together in what we call cross-scale interactions. These land{\textendash}atmosphere interactions that start small and propagate to have large impacts are the really big uncertainties that may become more frequent in the future as both the climate and land-use drivers change. Although our long-term data are invaluable at providing context for the present and future, the changing rules will make predictions of the future challenging without a strong understanding of the underlying mechanisms and their interactions that are driving those changes.

}, author = {Debra C. Peters} } @conference {JRN54425, title = {Forecasting regional grassland and shrubland responses to directional changes in climate using multi-year dry or wet period}, booktitle = {2015 LTER All Scientists Meeting}, year = {2015}, month = {08/2015}, address = {Estes Park, CO}, abstract = {

Ecologists are being challenged to predict ecosystem responses under changing climatic conditions. Although air temperatures are increasing, the magnitude and direction of change in precipitation (increase or decrease) are uncertain for many sites. Given that water availability is the primary driver of ecosystem processes in temperate grasslands and shrublands, these uncertainties in precipitation mean that ecologists must account for both possibilities. Long-term research sites (LTER, LTAR) provide natural experiments for ecological responses that occurred historically during multi-year drought or wet periods that can be used to make predictions under future climate scenarios. We tested three alternative hypotheses using long-term data (12 to \> 50y) of aboveground net primary production (ANPP) from seven sites in North America where precipitation showed sequences (\> 3 years) of wet periods, multi-year drought, and no trend years. We hypothesized that ANPP in wet (or drought) periods can be best explained by: (1) long-term relationships between ANPP and precipitation, (2) relationships between ANPP and precipitation in individual wet or dry years, or (3) relationships between ANPP and precipitation in wet or dry periods. We compared r2 values among equations at each site to determine the relationship with the best fit. For most sites across the region, the equation developed using ANPP and precipitation during drought periods was a better predictor of ANPP during drought compared with the long-term equation or the equation using individual dry years. In addition, the drought period equation had a steeper slope than the long-term equation. Thus, approaches that use long-term ANPP-precipitation relationships to predict ANPP during multi-year drought will result in over-estimates of ANPP. In contrast, in wet periods at some sites, the number of wet years in a row was a better predictor of ANPP than the amount of rainfall during the wet period. Cumulative processes, including plant-soil water feedbacks, sequential plant population processes, and plant or soil legacies may be operating to influence these temporal dynamics. These equations relating ANPP to precipitation during drought or number of wet years can be used to explain historic patterns, such as the 1930s drought or unusual grass recovery patterns, as well as improve future predictions under directional climate change.\  Paper No. 62.

}, author = {Debra C. Peters and Jin Yao and N. Dylan Burruss and Kris Havstad and O. E. Sala and J. D. Derner and John Hendrickson and Matt A Sanderson and John M Blair and S.L. Collins} } @proceedings {JRN54570, title = {Forecasting regional grassland and shrubland responses to directional changes in climate using multi-year dry or wet periods}, year = {2015}, month = {07/2015}, publisher = {LTER}, address = {Estes Park, Colorado}, abstract = {Ecologists are being challenged to predict ecosystem responses under changing climatic conditions. Although air temperatures are increasing, the magnitude and direction of change in precipitation (increase or decrease) are uncertain for many sites. Given that water availability is the primary driver of ecosystem processes in temperate grasslands and shrublands, these uncertainties in precipitation mean that ecologists must account for both possibilities. Long-term research sites (LTER, LTAR) provide natural experiments for ecological responses that occurred historically during multi-year drought or wet periods that can be used to make predictions under future climate scenarios. We tested three alternative hypotheses using long-term data (12 to > 50y) of aboveground net primary production (ANPP) from seven sites in North America where precipitation showed sequences (> 3 years) of wet periods, multi-year drought, and no trend years. We hypothesized that ANPP in wet (or drought) periods can be best explained by: (1) long-term relationships between ANPP and precipitation, (2) relationships between ANPP and precipitation in individual wet or dry years, or (3) relationships between ANPP and precipitation in wet or dry periods. We compared r2 values among equations at each site to determine the relationship with the best fit. For most sites across the region, the equation developed using ANPP and precipitation during drought periods was a better predictor of ANPP during drought compared with the long-term equation or the equation using individual dry years. In addition, the drought period equation had a steeper slope than the long-term equation. Thus, approaches that use long-term ANPP-precipitation relationships to predict ANPP during multi-year drought will result in over-estimates of ANPP. In contrast, in wet periods at some sites, the number of wet years in a row was a better predictor of ANPP than the amount of rainfall during the wet period. Cumulative processes, including plant-soil water feedbacks, sequential plant population processes, and plant or soil legacies may be operating to influence these temporal dynamics. These equations relating ANPP to precipitation during drought or number of wet years can be used to explain historic patterns, such as the 1930s drought or unusual grass recovery patterns, as well as improve future predictions under directional climate change.}, author = {Debra C. Peters and Jin Yao and N. Dylan Burruss and Kris Havstad and O. E. Sala and J. D. Derner and John Hendrickson and Matt A Sanderson and John M Blair and S.L. Collins} } @conference {JRN54428, title = {The Jornada Basin long term ecological research program}, booktitle = {2015 LTER All Scientists Meeting}, year = {2015}, month = {08/2015}, address = {Estes Park, CO}, abstract = {

Chihuahuan Desert landscapes exemplify the ecological conditions, vulnerability, and management challenges in arid and semi-arid regions around the world. The goal of the Jornada Basin Long Term Ecological Research program (JRN LTER) established in 1982 is to understand and quantify the key factors and processes controlling ecosystem dynamics and patterns in Chihuahuan Desert landscapes. In collaboration with the Jornada Experimental Range (USDA ARS), studies initiated in 1915 have been incorporated into the JRN LTER program. Previous research focused on desertification, a state change from perennial grasslands to woody plant dominance that occurs globally. Based on findings from growing long-term databases, the breadth of studies was expanded to include four additional state changes that occur in dryland systems worldwide: (1) a reversal to grassland states, (2) transitions among different states dominated by woody plants, (3) invasion by non-native grasses leading to novel states, and (4) transitions to human-dominated states. Processes of interest include water mediated plant-soil feedbacks, patch-scale contagion, landscape context, and time lags that are manifested as nonlinear dynamics and threshold behavior. The overall goal of Jornada LTER-VI (2012-2018) is to understand and quantify the mechanisms that generate alternative natural and human-dominated states in dryland ecosystems, and to predict future states and their consequences for the provisioning of ecosystem services. A modified conceptual framework and integrated research plan in LTER-VI is being used to: (1) test specific elements by coupling existing long-term studies of patterns with new experiments aimed at elucidating processes, (2) integrate data from long-term studies in novel ways to address new questions, both at the JRN and in the surrounding region, and (3) forecast alternative future landscapes and consequences for ecosystem services under a changing environment. The research is organized around two major geomorphic units that characterize the Chihuahuan Desert, and that contain on-going long-term studies and a sensor network. Long-term studies are being combined with new mechanistic experiments designed to identify dominant processes and drivers with a focus on pattern-process relationships that transcend scales. The generality of this framework is being assessed with cross-site and regional studies. Simulation modeling is being used to synthesize and integrate data, both to understand current patterns and to predict future dynamics. New socio-economic studies and scenarios based on the Ecosystem Millennium Assessment is placing Jornada research into a broader socio-economic-ecologic context. Research is resulting in five major products: (1) new understanding of state changes, in particular in drylands, that lead to theory development, testable hypotheses, and new experiments; (2) accessible data and visualization tools applicable at multiple scales; (3) explanatory and predictive relationships between drivers, patterns, and processes that can be used to (4) develop scenarios of alternative human- and natural-dominated states with assessments of their impacts on ecosystem services; and (5) usable information transfer to a broad audience including K-12 students and teachers, and NGO and government agency land resource managers. Please see the Special Issue in Frontiers in Ecology and the Environment (Feb. 2015), "Emerging Perspectives and Shifting Paradigms in Water-Limited Systems" for recent findings from the Jornada.\  Paper No. 73.

}, author = {Debra C. Peters and Brandon T Bestelmeyer and Brandon T Bestelmeyer and Kris Havstad and Curtis H. Monger and Gregory S. Okin and O. E. Sala and Enrique Vivoni and Steven R. Archer and Danielle Duni} } @article {JRN53951, title = {Harnessing the power of big data: infusing the scientific method with machine learning to transform ecology}, journal = {Ecosphere}, volume = {5}, year = {2014}, month = {06/2014}, chapter = {Article 67}, abstract = {

Most efforts to harness the power of big data for ecology and environmental sciences focus on data and metadata sharing, standardization, and accuracy. However, many scientists have not accepted the data deluge as an integral part of their research because the current scientific method is not scalable to large, complex datasets. Here, we explain how integrating a dataintensive, machine learning approach with a hypothesis-driven, mechanistic approach can lead to a novel knowledge, learning, analysis system (KLAS) for discovery and problem solving. Machine learning leads to more efficient, user-friendly analytics as the streams of data increase while hypothesis-driven decisions lead to the strategic design of experiments to fill knowledge gaps and to elucidate mechanisms. KLAS will transform ecology and environmental sciences by shortening the time lag between individual discoveries and leaps in knowledge by the scientific community, and will lead to paradigm shifts predicated on open access data and analytics in a machine learning environment.

}, keywords = {analytics, data deluge, long-term data, machine learning, open data, paradigm shifts}, doi = {10.1890/ES13-00359.1}, url = {/files/bibliography/14-013.pdf}, author = {Debra C. Peters and Kris Havstad and Cushing, Judy and Craig Tweedie and Fuentes, Olac and Villanueva-Rosales, Natalia} } @article {JRN52693, title = {Mechanisms of grass response in grasslands and shrublands during dry or wet periods}, journal = {Oecologia}, volume = {174}, year = {2014}, pages = {1323-1334}, chapter = {1323}, abstract = {

Multi-year climatic periods are expected to increase with global change, yet long-term data are often insufficient to document factors leading to ecological responses. We used a suite of long-term datasets (1993-2010) to examine the processes underlying different relationships between aboveground net primary production (ANPP) and precipitation in wet and dry rainfall periods in shrublands and grasslands in the Chihuahuan Desert. We hypothesized that trends in ANPP can be explained by different processes associated with their dominant grasses [Bouteloua eriopoda (grasslands); Sporobolus flexuosus (shrublands)], and with ecosystem properties that influence soil water dynamics with feedbacks to ANPP. We compared datasets on recruitment and growth for seven years with no trend in precipitation followed by a four-year drought and five consecutive wet years. We integrated these data in a simulation model to examine the importance of positive feedbacks. In grasslands, ANPP was linearly related to precipitation regardless of rainfall period, primarily as a result of stolon recruitment by B. eriopoda. A lag in responses suggests the importance of legacies associated with stolon density. In shrublands, ANPP was only related to rainfall in the wet period when it increased nonlinearly as the number of wet years increased. Seed availability increased in the first year, and seedling establishment occurred two to four years later. Increases in biomass, litter, and simulated transpiration beginning in the third year corresponded with increases in ANPP. Understanding the processes underlying ecosystem dynamics in multi-year dry or wet periods is expected to improve predictions under directional increases or decreases in rainfall.

}, keywords = {Bouteloua eriopoda, Demographic processes, grasslands, Plant-soil water feedbacks, Sporobolu flexuosus}, doi = {10.1007/s00442-013-2837-y}, url = {/files/bibliography/14-004.pdf}, author = {Debra C. Peters and Jin Yao and Dawn M. Browning and A. Rango} } @article {JRN53986, title = {North American Biomes}, journal = {Oxford Bibliographies}, year = {2014}, month = {08/2014}, abstract = {

The North America biome includes the major ecoregions that make up the land area of Canada, the United States, Mexico, and countries in Central America. The biome is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. This large area (over 24 x 106 km2) is characterized by a broad range of temperature and precipitation that result in nine major ecoregions, from boreal forests and tundra near the North Pole to tropical deciduous and coniferous forests in the south near the equator.\  Temperate forests (deciduous, coniferous), grasslands and shrublands, savannas, and deserts occur in the central part. Landscape-scale patterns in contemporary ecosystems within each ecoregion reflect variability in climate and soil parent material combined with human activities that have increased in extent and intensity over the past several centuries. Within the biome, ecoregions can be influenced by the movement of organisms, water and sediment, fire, and air chemistry from other ecoregions in the biome. At the scale of the biome, connections with other locations on Earth can lead to invasion by exotic species including pests and pathogens, large climatic events such as hurricanes and drought, and changes in air quality through dust storms and volcanic eruptions. These tele-connections often occur infrequently, yet with large and surprising effects on ecosystem properties and dynamics. Increasing awareness of these broad-scale dynamics that connect biomes globally is leading to new avenues of research that intersect ecology with other disciplines.

}, doi = {10.1093/OBO/9780199830060-0099}, author = {Debra C. Peters and Stacey L P Scroggs and Jin Yao} } @article {JRN53928, title = {Taking the pulse of a continent: Expanding site-based research infrastructure for regional- to continental-scale ecology}, journal = {Ecosphere}, volume = {5}, year = {2014}, month = {03/2014}, chapter = {Article 29}, abstract = {

Many of the most dramatic and surprising effects of global change on ecological systems will occur across large spatial extents, from regions to continents. Multiple ecosystem types will be impacted across a range of interacting spatial and temporal scales. The ability of ecologists to understand and predict these dynamics depends, in large part, on existing site-based research infrastructures that were developed in response to historic events. Here we review how unevenly prepared ecologists are, and more generally, ecology is as a discipline, to address continental-scale questions given these pre-existing site-based capacities, and we describe the changes that will be needed to effectively pursue these broad-scale questions in the future. We first review the types of approaches commonly used to address questions at broad scales, and identify the research, cyber-infrastructure, and cultural challenges associated with these approaches. These challenges include developing a detailed, mechanistic understanding of the drivers and responses of ecosystem dynamics across a large, diverse geographic extent. Measurements of fluxes or flows of materials, energy or information across levels of biological organization or spatial units are challenging for the mosaic of natural and human-dominated ecosystems found across large spatial extents. The diversity of methods, sampling protocols, and data acquisition technologies make post-hoc comparisons of ecosystems using existing data challenging, and data collected using standardized methods across sites require coordination and teamwork. Sharing of data and analytics to create derived data products are needed for multi-site studies, but this level of collaboration is not part of the current ecological culture. We then discuss the strengths and limitations of current site-based research infrastructures in meeting these challenges, and describe a path forward for continental-scale ecological research that integrates existing infrastructures with emerging technologies to more effectively address broad-scale questions.

}, keywords = {connectivity, cyber-infrastructure, data interoperability, ecological culture, ecological networks, macro-ecology, open science}, doi = {10.1890/ES13-00295.1}, url = {/files/bibliography/14-003.pdf}, author = {Debra C. Peters and Loescher, H.W. and M.D. San Clements and Kris Havstad} } @inbook {JRN52664, title = {Cross-site comparisons of state-change dynamics}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {36-41}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {4}, address = {Springfield, Virginia}, abstract = {

Changes in the state of a system, for example from grasslands to shrublands or from dominance by one fish species to another species, with associated changes in other parts of the system, are often irreversible. Most of these state changes bring forth negative impacts on ecosystem, resulting in altered levels of biodiversity, rates of nutrient cycling, changes in air and water quality, and increased losses of soil and nutrients by wind and water erosion.\  This chapter illustrated six examples of state changes in various types of ecosystems: vegetation state changes in deserts, penguin dynamics in Antarctica, fish dynamics in Wisconsin lakes, plankton dynamics in the Pacific Ocean, subtidal dynamics off Pacific Coast, and shifts in coastal fish assemblages in the Pacific Ocean.\  These examples clearly show the impact of global environmental change (warming, invasive species, altered trophic structure) on the abundance and distribution of dominant and subordinate species in aquatic, marine, and terrestrial systems. Because this era of rapid environmental change is only beginning to be manifest in species responses, long-term data will continue to be needed to quantify and predict the non-linear system responses that are likely to occur in the future.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-4.pdf}, author = {Debra C. Peters and William R. Fraser and T. K. Kratz and Mark D. Ohman and Andrew Rassweiler and Sally J. Holbrook and Russell J. Schmitt} } @inbook {49858, title = {Desertification of Rangelands}, booktitle = {Climate Vulnerability: Understanding and Addressing Threats to Essential Resources}, series = {Climate Vulnerability}, volume = {4}, number = {4}, year = {2013}, pages = {239-258}, publisher = {Academic Press}, organization = {Academic Press}, edition = {First}, abstract = {Desertification, the broad-scale conversion of perennial grasslands to dominance by xerophytic shrubs, and the attendant consequences to ecosystem services has affected arid and semiarid regions globally over the past several centuries. This state change is expected to continue in the future as environmental drivers continue to change. It is generally well-recognized that desertification is a cumulative threat that explicitly includes both climatic (e.g., drought) and land-use drivers (e.g., livestock overgrazing and inappropriate conversions of rangeland to cropland).\  However, a basis for ranking the relative importance of these drivers is lacking for many locations. In addition, the emergence of additional drivers (e.g., non-native forbs and grasses modifying historic fire regimes), will result in even more complex dynamics in the future. Clearly, directional changes in climate can have unanticipated effects, in particular for dryland regions with low and variable precipitation and high temperatures in the growing season. However, any change in climate will be operating across diverse landscapes that include a mosaic of human-dominated and natural states, each governed by different drivers and susceptible to different threats. Accounting for the separate and interactive effects of these threats on grassland-shrubland transitions will be necessary as we move forward into a difficult to predict, if not unknown, environmental world.}, keywords = {biodiversity, climate, desertification, dryland ecosystems, feedbacks, grasslands, invasive species, land management, land use, land-atmosphere interactions, shrublands, state change, thresholds, water, wind}, doi = {10.1016/B978-0-12-384703-4.00426-3}, url = {/files/bibliography/13-014.pdf}, author = {Debra C. Peters and Steven R. Archer and Brandon T Bestelmeyer and Brooks, Andrew and Joel R. Brown and Comrie, Andrew and Gimblett, H. Randy and Goldstein, Joshua H. and Kris Havstad and Lopez-Hoffman, L. and Curtis H. Monger and Gregory S. Okin and A. Rango and O. E. Sala and Craig Tweedie and Enrique Vivoni} } @inbook {JRN52667, title = {Disturbance regimes and ecological responses across sites}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {58-71}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {9}, address = {Springfield, Virginia}, abstract = {

Disturbances affect ecosystems in almost limitless ways. The effects of disturbances extend beyond the initial impacts that are usually visible to the human eye. Therefore, for many disturbances long-term data are needed to unravel their effects.\  This chapter first presents characteristics of disturbances for each of four major classes of disturbance: climatic, physical, biotic, and anthropogenic.\  It then discusses ecosystem responses by disturbance class.\  For climatic disturbances, ecosystem responses to hurricanes, drought, and global warming are discussed; for physical disturbances, wildfire on land and wave height in ocean; for biotic disturbance, herbivores feeding on lower tropic levels, invasive species, and a plant disease; for anthropogenic disturbance, changes in land use patterns.\  These long-term records of ecosystem responses to disturbance illustrate the complexity of disturbance effects. Ecosystem responses are influenced by multiple disturbances and interactions with other factors, which make it very difficult to attribute cause and effect. Clearly large-scale, multiple-site experiments are needed to further unravel the relationships between particular disturbance events and ecosystem responses.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-9.pdf}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Tepley, A. J. and F. J. Swanson} } @inbook {49857, title = {Landscape Diversity}, booktitle = {Encyclopedia of Biodiversity}, volume = {4}, year = {2013}, pages = {476-487}, publisher = {Academic Press}, organization = {Academic Press}, edition = {2}, address = {Waltham, MA}, abstract = {

While biodiversity is usually considered at the species level, maintenance of biodiversity requires management at higher levels of organization, particularly at the landscape scale. It is difficult to manage for each threatened species individually. Alternatively, management can focus on the ecosystems that contain these species, and on the landscapes in which ecosystems are found. There are three basic characteristics of landscapes that affect their diversity: structure, function, and dynamics. Structure is the most well-understood element of landscapes. It is also the most obvious{\textemdash}nearly any aerial view will show a mixture of different landforms, habitats, or vegetation types. The characteristics of patches and the spatial relationships among patches are important components of landscapes. Function is concerned with interactions among the spatial elements of a landscape, including flows of energy, materials, and species among patches. Landscape dynamics includes characteristics of both structure and function in order to examine changes in pattern and process over time. This article discusses each element in turn, and also considers the underlying determinants of landscape structure, including environmental heterogeneity and disturbance patterns. We then discuss issues in biodiversity management, and conclude with a case study of landscape diversity at the Sevilleta National Wildlife Refuge Long-Term Ecological Research site in central New Mexico, United States.

}, doi = {10.1016/B978-0-12-384719-5.00084-8}, url = {files/bibliography/13-009.pdf}, author = {Debra C. Peters and Sarah Goslee and S.L. Collins and J. R. Gosz} } @inbook {JRN52675, title = {Long-term research across sites, ecosystems, and disciplines: synthesis and research needs}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {226-233}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {17}, address = {Springfield, Virginia}, abstract = {

The EcoTrends Project is one of the first attempts to standardize, simplify, integrate, and visualize data from diverse terrestrial, aquatic, and marine ecosystems to promote understanding and synthesis by a broad audience. This chapter discusses key scientific results from this project, describes developing conceptual and operational frameworks for cross-site synthesis, and provides recommendations for future research. Key results are: mean air temperature has increased at 24 sites, and annual precipitation has increased at 9 sites with no obvious spatial distribution in either climate variable. Trends in atmospheric chemistry show clear patterns across the continent with reduced deposition of nitrate and sulfate in precipitation through time in the eastern U.S. compared with the West. Patterns in stream water chemistry across sites do not reflect broad-scale patterns in atmospheric chemistry; thus local conditions have strong influences on chemical inputs to and losses from streams. Human population density has increased at all sites, although at different rates. Biotic data are often idiosyncratic in that they reflect high spatial and temporal variability inherent in biological phenomenon.\  It is proposed that cross-site synthesis studies should integrate three aspects of ecological research: depth (individual sites being studied in great detail), length (data being collected over long periods), and breadth (phenomena being studied across broad spatial extents).\  The strongest recommendation for future research is to make data and associated metadata easily accessible to and usable by others.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-17.pdf}, author = {Debra C. Peters} } @inbook {JRN52669, title = {Long-term trends in climate and climate-related drivers}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {81-114}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {11}, address = {Springfield, Virginia}, abstract = {

This chapter shows long-term data and trends in climate and climate-related drivers for each site.\  It contains a brief introduction to the topic, and methods of measurements, selection of variables, and their data source. It consists primarily of a large number of figures showing long-term data for different variables.\  On land, air temperature (mean, minimum, and maximum), precipitation, Palmer Drought Severity Index, and Walter-Lieth climate diagrams are selected.\  In water, streamflow, sea level, ice duration, water clarity, and water temperature are selected.\  Two types of graphs are included to show trends in the variables and to provide a sense of change across a range of spatial scales (continent, site) for each variable: maps at continental scale showing either the mean across years or the slope of the regression line (if significant) across time, and site-scale data through time.\  Air temperatures are increasing in at least one variable (minimum, mean, maximum) for 27 of the 50 sites.\  Sea level is increasing at all 11 coastal sites.\  Observing these trends in climate across multiple ecosystems across continents is only possible with spatially extensive, long-term data collection and analysis, such as provided by the EcoTrends Project.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-11.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman} } @book {JRN52662, title = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {378}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, address = {Springfield, Virginia}, abstract = {

The Eco Trends Editorial Committee sorted through vast amounts of historical and ongoing data from 50 ecological sites in the continental United States including Alaska, several islands, and Antarctica to present in a logical format the variables commonly collected.\  This report presents a subset of data and variables from these sites and illustrates through detailed examples the value of comparing long-term data from different ecosystem types. This work provides cross-site comparisons of ecological responses to global change drivers, as well as long-term trends in global change drivers and responses at site and continetal scales.\  Site descriptions and detailed data also are provided in the appendix sections.

\⇒ This book is available for download (PDF format) below

\⇒ Available from http://www.ars.usda.gov/is/np/indexpubs.html

\⇒ Copies may be purchased in various formats (microfiche, photocopy, CD, print on demand) from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161, 800-553-6847, www.ntis.gov

Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change\  (download PDF - 313 MB)

Download the book in PDF in it\&$\#$39;s entirety (above) or by section (below)

Contents

Introduction to Cross-Site Comparisons and History and Organization of the EcoTrends Project\  (8.29 MB)

Cross-Site Comparisons of Ecological Responses to Global Change Drivers\  (21.8 MB)


Long-Term Trends in Global Change Drivers and Responses at Site and Continental Scales\  (197 MB)


Appendices \& Index\  (79 MB)

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029 Bk.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman and R. B. Waide and Jin Yao} } @inbook {JRN52676, title = {Long-term trends in ecological systems: An introduction to cross-site comparisons and relevance to global change studies}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {1-20}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {1}, address = {Springfield, Virginia}, abstract = {

This chapter explains the importance of long-term data to ecological studies and the needs of creating a way to provide accessible and comparable multi-site long-term data. The Earth{\textquoteright}s environment is changing in many ways at local, regional, and global scales. Dramatic changes have occurred in climate, land cover, and habitat availability over the past several centuries. Long-term data (\> 10 years) are needed to assess the rate and direction of change, to distinguish directional trends in these changes (e.g., persistent increases or decreases) from short-term variability (e.g., multi-year cycles), and to forecast environmental conditions in the future.\  It also sets up the stage for the rest of the chapters in the book, presenting the purposes, audience and practical applications of the book, explaining how the study sites, variables, and data sets are selected, and how the data are presented and analyzed, and laying out the organization of the book.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-1.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman and R. B. Waide and Jin Yao} } @inbook {JRN52671, title = {Long-term trends in human demography and economy across sites}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {162-190}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {13}, address = {Springfield, Virginia}, abstract = {

This chapter shows long-term data and trends in human demography and economy for each site.\  It contains a brief introduction to the topic, and methods of measurements, selection of variables, and their data source. It consists primarily of a large number of figures showing long-term data for different variables.\  Total population, the percentage of the population living in urban areas, and the density of people in the counties associated with each site are selected.\  Four economic variables fore each focal county of a site are also selected: the percentage of the population employed by one of four economic sectors: commercial industries, farming, manufacturing, and service industries.\  Two types of graphs are included to show change through time across a range of spatial scale for each variable: maps of continental scale showing either the \% change in total population for four time periods (1800 to 1850; 1850 to 1900, 1900 to 1950, 1950 to 2000) or the \% of the population that was urban in each of four time periods (1850, 1900, 1950, 2000); and maps and graphs showing site-scale data through time. The settlement of the country occurred from the east coast and then to the west coast by 1900, and then to the interior between 1900 and 1950. Losses of population in the Midwest occurred between 1950 and 2000. Most areas of the country had a high percentage of urban population by 1950. Urbanization continued for most of the country until 2000 with the Northeast, Appalachian Mountains, and northern Wisconsin providing notable exceptions.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-13.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman} } @inbook {JRN52670, title = {Long-term trends in precipitation and surface water chemistry}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {115-161}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {12}, address = {Springfield, Virginia}, abstract = {

This chapter shows long-term data and trends in precipitation and surface water chemistry for each site.\  It contains a brief introduction to the topic, and methods of measurements, selection of variables, and their data source. It consists primarily of a large number of figures showing long-term data for different variables.\  Volume-weighted concentration (mg/L) and area-based wet deposition (kg/ha) from precipitation, and concentration in surface water (mg/L) of nitrogen (as nitrate and ammonium), sulfur (as sulfate), chloride, and calcium are selected.\  Two types of graphs are included to show trends in the variables and to provide a sense of change across a range of spatial scales (continent, site) for each variable: maps at continental scale showing either the mean across years or the slope of the regression line (if significant) across time, and site-scale data through time.\  Nitrate and sulfate deposition are decreasing in many Eastern sites, consistent with efforts to control emissions of acid-causing nitrogen and sulfur from power plants in this part of the country.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-12.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman} } @inbook {JRN52672, title = {Long-term trends in production, abundance, and richness of plants and animals}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {191-205}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {14}, address = {Springfield, Virginia}, abstract = {

This chapter shows long-term data and trends in production, abundance, and richness of plants and animals for each site.\  It contains a brief introduction to the topic, and methods of measurements, selection of variables, and their data source. It consists primarily of a large number of figures showing long-term data for different variables.\  Net primary production, plant biomass and species richness, animal abundance and species richness are selected.\  Figure of site-scale data through time of each variable is shown, and a regression line is shown if the relationship is significant and the trend appears linear.\  The site graphs are shown on a continental map with similar sites to allow comparison among sites.\  At many sites, multiple locations are sampled for plant and animal dynamics. The large within-site variability in responses often overwhelms trends through time.\  Although plant response variables of ANPP, richness, and biomass are sampled for most sites to allow cross-site comparisons, animal response variables are more variable among sites with fewer comparable groups. These results indicate that each site selects representative trophic groups from the local ecosystems, instead of attempting to standardize across sites.\  The length of the time series also varies across sites which further complicates cross-site comparisons.

}, keywords = {atmospheric chemistry, climate change, cross-site comparisons, disturbance, ecological response, ecology, ecosystem, EcoTrends, experimental forests, global change, human demography, human population growth, Long Term Ecological Research (LTER), long-term datasets, precipitation, rangeland, rangeland research stations, surface water chemistry}, url = {/files/bibliography/13-029-14.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J. Morgan and A. K. Knapp and T. K. Kratz and Mark D. Ohman} } @proceedings {JRN54531, title = {Deciphering landscape complexity to predict (non)linear responses to extreme climatic events}, volume = {H54D-04}, year = {2012}, month = {12/2012}, publisher = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {Extreme events are increasing in frequency and magnitude for many landscapes globally. Ecologically, most of the focus on extreme climatic events has been on effects of either short-term pulses (floods, freezes) or long-term drought. Multi-year increases in precipitation are also occurring with little known consequences, in particular for landscapes with high spatial variation in soils, geomorphology, and vegetation. We used long-term data from the Chihuahuan Desert in North America to compare ecosystem responses to precipitation in dry, average, and wet periods for a landscape consisting of five major ecosystem types. These types are dominated by one of two life forms (grasses or shrubs) that are located on different soils and topographic positions. We then used a process-based simulation model integrated with additional long-term data to identify the processes driving dynamics in each climatic period for different landscape locations. For some ecosystem types, ecological responses in average and dry periods could be linearly extrapolated to predict responses in an extended wet period, and the same set of processes occurred regardless of climatic period. However, for much of the landscape, a different set of biotic-abiotic processes and their feedbacks became operative in a wet period. This sequence of processes led to nonlinear dynamics through time. Our results show that dynamics of complex landscapes can be deciphered given information and long-term data on linked biotic-abiotic processes across spatial and temporal scales. Understanding the role of sequential processes and landscape complexity in ecosystem responses to multi-year climatic patterns is needed to improve predictions of landscape scale responses to climate.}, author = {Debra C. Peters and Jin Yao and Dawn M. Browning and Danielle Duni and Haitao Huang and A. Rango} } @article {49900, title = {Directional climate change and potential reversal of desertification in arid and semiarid ecosystems}, journal = {Global Change Biology}, volume = {18}, year = {2012}, month = {01/2012}, pages = {151-163}, chapter = {151}, abstract = {Our objective was to determine if long-term increases in precipitation can maintain grasslands susceptible to desertification, and initiate a reversal of historic regime shifts on desertified shrublands. Perennial grass production and species richness in a multi-year wet period were hypothesized to be greater than expected based on precipitation in a sequence of dry years. These responses were expected to differ for grasslands and shrublands with different dominant species and topo-edaphic properties. Long-term trends in desertification were documented using vegetation maps beginning in 1858, 1915, 1928, and 1998). These trends were compared with herbaceous and woody species responses to a sequence of dry (1994\–2003) and wet years (2004\–2008) for two grassland (uplands, playas) and three desertified shrubland types (honey mesquite, creosotebush, tarbush) in the Chihuahuan Desert. Analyses showed that both types of grasslands decreased in spatial extent since 1858 whereas areas dominated by mesquite or creosotebush increased. Production of upland grasslands in the wet period was greater than expected based on responses during the dry period whereas the relationships between species richness and precipitation was the same for both periods. Precipitation was not important to responses in playa grasslands in either period. For all ecosystem types, the production response in wet years primarily was an increase in herbaceous plants, and the most pronounced responses occurred on sandy sites (upland grasslands, mesquite shrubland). Results suggest that multiple wet years are needed to initiate a sequence of grass establishment and survival processes that can maintain upland grasslands without management inputs and lead to a state change reversal in desertified shrublands. Restoration strategies need to take advantage of opportunities provided by future climates while recognizing the importance of ecosystem type.}, keywords = {extreme events, grasslands, regime shift, shrublands, spatial content, wet-dry climatic periods}, doi = {10.1111/j.1365-2486.2011.02498.x}, url = {/files/bibliography/12-002.pdf}, author = {Debra C. Peters and Jin Yao and O. E. Sala and John P. Anderson} } @inbook {49897, title = {Grassland simulation models: A synthesis of current models and future challenges}, booktitle = {Handbook of Ecological Models Used in Ecosystem and Environmental Management}, year = {2012}, pages = {175-201}, publisher = {CRC Pess}, organization = {CRC Pess}, chapter = {7}, address = {Baco Raton, FL}, abstract = {

This chapter synthesizes the different kinds of simulation models commonly used to address questions about controls on dynamics of perennial grasslands. Five major classes of models are described using specific models as examples: (1) demographic, (2) physiological, (3) physical, (4) biogeochemistry, and (5) dynamic global vegetation. Each class of model is described relative to the types of questions that can be addressed, and then its advantages and limitations are stated. Recommendations on which model to select for different kinds of questions are given as well as future challenges in grassland modeling are described. The chapter contains five tables, one for each model class, that provide detailed information on input parameters, spatial and temporal resolution, and response variables for specific models that will aide readers in selecting models for use in different situations. In addition, a comprehensive literature cited includes many of the more commonly used and published models for grasslands.

}, isbn = {978-1-4398-1812-1}, url = {/files/bibliography/12-004.pdf}, author = {Debra C. Peters} } @article {49898, title = {How can science be general, yet specific: The conundrum of rangeland science in the 21st Century}, journal = {Rangeland Ecology and Management}, volume = {65}, year = {2012}, month = {11/2012}, pages = {613-622}, chapter = {613}, abstract = {

A critical challenge for range scientists is to provide input to management decisions for land units where little or no data exist. The disciplines of range science, basic ecology, and global ecology use different perspectives and approaches with different levels of detail to extrapolate information and understanding from well-studied locations to other land units. However, these traditional approaches are expected to be insufficient in the future as both human and climatic drivers change in magnitude and direction, spatial heterogeneity in land cover and its use increases, and rangelands become increasingly connected at local to global scales by flows of materials, people, and information. Here we argue that to overcome limitations of each individual discipline, and to effectively address future rangeland problems, scientists will need to successfully integrate these disciplines in novel ways. The objectives of this paper are: (1) to describe the background, historical development, and limitations of current approaches, (2) to describe an integrated approach that takes advantage of the strengths and minimizes the weaknesses of each individual approach, and (3) to discuss the challenges and implications of this integrated approach to the future of range science when climate and human drivers are non-stationary. This integration will be critical for applying range science to the management of specific land units, and will contribute to and benefit from the development of general ecological principles as well as to addressing problems facing society at regional, continental, and global scales.

}, keywords = {downscaling, extrapolation, global ecology, integration, nonstationarity, spatial heterogeneity}, doi = {10.2111/REM-D-11-00178.1}, url = {/files/bibliography/12-034.pdf}, author = {Debra C. Peters and Jayne Belnap and J. Ludwig and S.L. Collins and Paruelo, J. and Hoffman, M. Timm and Kris Havstad} } @article {JRN54212, title = {Long-term experimental loss of foundation species: consequences for dynamics at ecotones across heterogeneous landscapes}, journal = {Ecosphere}, volume = {3}, year = {2012}, month = {03/2012}, pages = {1-23}, chapter = {Article 27}, abstract = {

Biome transition zones where species co-exist near their geographic limits are expected to be among the most responsive to changes in climate that result in mortality of foundation species. Long-term (.13 years) patterns in dominance and cover of functional types were examined following the annual experimental removal of one of three foundation species at an arid-semiarid biome transition zone.\  Objectives were to identify key processes influencing these patterns, and to predict future landscape-scale dynamics following mortality of different foundation species. Aboveground biomass of dominant species was removed from 334 m plots. Cover by species on control and removal plots was estimated annually in communities with a single dominant species, and in ecotonal communities with two dominant species across two types of ecotones (semiarid grassland-arid grassland, arid grassland-arid shrubland).\  For most species and functional types, trends in cover through time were related to the remaining species assemblages rather than to variable climatic conditions. In ecotonal communities, resident co-dominant species increased to dominance following the loss of a foundation species with little change in community composition. In mono-dominated communities, dominant species loss resulted in a shift to species that are currently sub-dominants of the same functional type as the species that was removed. \ Subdominant perennial grass and shrub species increased rapidly following removals in most grassland locations.\  Annuals and perennial forbs had variable cover values through time that were not clearly related to pulses in precipitation and were not synchronized across locations. The most common response regardless of the identity of the foundation species removed or the community type was an increase in cover by subdominant grasses and by the arid grass species (Bouteloua eriopoda). The rate of increase by B. eriopoda depended on initial cover, and resulted from both vegetative growth and seedling recruitment from other locations. Seed dispersal and seedling recruitment from other locations were not found for the semiarid grass, Bouteloua gracilis or the arid shrub, Larrea tridentata. Because B. eriopoda is more susceptible to shrub invasion, drought, and livestock grazing than the other two foundation species, widespread loss of either of the other species and subsequent increase in B. eriopoda is expected to result in an increase in landscape scale vulnerability to these environmental drivers. The extent and magnitude of this change invulnerability will depend on the ability of B. eriopoda to respond based on the micro-environmental conditions of the site regardless of which species (B. gracilis, L. tridentata) is lost.

}, keywords = {arid, biome transitions, Chihuahuan Desert, dominant species, experimental removals, grasslands, mortality, semiarid, Shorrgrass Steppe, shrublands}, doi = {10.1890/ES11-00273.1}, url = {/files/bibliography/12-042.pdf}, author = {Debra C. Peters and Jin Yao} } @article {49977, title = {Cross-site comparisons of state change dynamics}, year = {2011}, keywords = {cross-site comparisons, cross-site reserarch, state change dynamics}, author = {Debra C. Peters and William R. Fraser and T. K. Kratz and Mark D. Ohman and Andrew Rassweiler and Sally J. Holbrook and Russell J. Schmitt} } @article {49982, title = {Cross-system comparisons elucidate disturbance complexities and generalities}, journal = {Ecosphere}, volume = {2}, year = {2011}, month = {07/2011}, pages = {Article 81}, chapter = {1}, abstract = {Given that ecological effects of disturbance have been extensively studied in many ecosystems, it is surprising that few quantitative syntheses across diverse ecosystems have been conducted. Multi-system studies tend to be qualitative because they focus on disturbance types that are difficult to measure in an ecologically relevant way. In addition, synthesis of existing studies across systems or disturbance types is challenging because sufficient information needed for analysis is not easily available. Theoretical advances and improved predictions can be advanced by generalizations obtained from synthesis activities that include multiple sites, ecosystems, and disturbance events. Building on existing research, we present a conceptual framework and an operational analog to integrate this rich body of knowledge and to promote quantitative comparisons of disturbance effects across different types of ecosystems and disturbances. This framework recognizes individual disturbance events that consist of three quantifiable components: (1) environmental drivers, (2) initial system properties, and (3) physical and biological mechanisms of effect, such as deposition, compaction, and combustion. These components result in biotic and abiotic legacies that can interact with subsequent drivers and successional processes to influence system response. Through time, a coarse-scale quasi-equilibrial state can be reached where variation in drivers interacting with biotic processes and feedbacks internal to the system results in variability in dynamics. At any time, a driver of sufficient magnitude can push the system beyond its realm of natural variability to initiate a new kind of event. We use long-term data from diverse terrestrial ecosystems to illustrate how our approach can facilitate cross-system comparisons, and provide new insights to the role of disturbance in ecological systems. We also provide key disturbance characteristics and measurements needed to promote future quantitative comparisons across ecosystems.}, keywords = {disburbance event, disturbance type, drought, ecological theory, global change, hurricane legacies, overgrazing, thresholds, wildfire}, doi = {10.1890/es11-00115.1}, url = {/files/bibliography/11-015.pdf}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Steward T.A. Pickett and Danielle Duni and Rocha, Adrian V. and F. J. Swanson and C. Laney and J. W. Jones (eds.)} } @article {49976, title = {Disturbance regimes and ecological responses across sites}, year = {2011}, keywords = {cross-site comparisons, disturbance regimes, ecological responses, ecological systems, global change}, author = {Debra C. Peters and Ariel E. Lugo and F.S. Chapin III and Tepley, A. J. and F. J. Swanson} } @inbook {49979, title = {Globalization: Ecological consequences of global-scale connectivity in people, resources, and information}, booktitle = {The Systemic Dimension of Globalization}, year = {2011}, pages = {211-232}, publisher = {InTech}, organization = {InTech}, chapter = {11}, abstract = {Globalization is a phenomenon affecting all facets of the Earth System. Within the context of ecological systems, it is becoming increasingly apparent that global connectivity among terrestrial systems, the atmosphere, and oceans is driving many ecological dynamics at finer scales and pushing thresholds of change. In addition, fine-scale ecological dynamics can propagate spatially to influence broad spatial extents with feedbacks to global drivers. Because global change drivers and ecosystem dynamics are changing nonlinearly through time for many locations, it is critical that connections across different aspects of the Earth System be examined to improve both understanding and prediction of future dynamics. Here, three classes of connectivity events are described that emerge from a common, integrated framework. Each class has different characteristics that connect ecological systems at fine to broad scales. Examples are provided to illustrate how various global change drivers can influence and interact with heterogeneity in land surface properties of vegetation and soil pattern to either synchronize, attenuate or amplify impacts of drivers on ecological systems. Approaches are also described to quantifying global change impacts and ecological responses when locations are connected spatially.}, isbn = {978-953-307-384-2}, url = {/files/bibliography/11-019.pdf}, author = {Debra C. Peters} } @article {49971, title = {Long-term research across sites, ecosystems, and disciplines: synthesis and research needs}, year = {2011}, keywords = {cross-site research, long-term research, synthesis}, author = {Debra C. Peters} } @article {49974, title = {Long-term trends in climate and climate-related drivers}, year = {2011}, keywords = {climate drivers, climate-related drivers, long-term trends}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J.M. and A. K. Knapp and T. K. Kratz and Mark D. Ohman and R. B. Waide and Jin Yao} } @article {49973, title = {Long-term trends in precipitation and surface water chemistry}, year = {2011}, keywords = {ecological systems, global change, long-term trends, precipitation, surface water chemistry}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J.M. and A. K. Knapp and T. K. Kratz and Mark D. Ohman and R. B. Waide and Jin Yao} } @article {49970, title = {Long-term trends in production, abundance, and richness of plants and animals}, year = {2011}, abstract = {

Trends in biotic structure have been of interest in the United States since the establishment of the Division of Biological Survey in the U.S. Department of Agriculture in the late 1890s. Changes in iotic structure can serve as a bellwether for quantifying the effects of climate change, land-use change, and the spread of exotic species, as well as the loss of rare and endangered species. Considerable evidence suggests that changes in biotic structure can have significant consequences for ecosystem functioning and the provisioning of ecosystems goods and services. In this chapter, we first describe common methods for measuring responses of plants and animals and our rationale for the selection of variables included in this book. We then show graphs of biotic data through time for each site arrayed across the continent.

}, keywords = {animal abundance, animal production, animal species richness, ecological systems, global change, long-term trends, plant abundance, plant production, plant species richness}, url = {files/bibliography/JRN00577.pdf}, author = {Debra C. Peters and C. Laney and Ariel E. Lugo and S.L. Collins and Charles T. Driscoll and Peter M. Groffman and Grove, J.M. and A. K. Knapp and T. K. Kratz and Mark D. Ohman and R. B. Waide and Jin Yao} } @inbook {49978, title = {Perspectives on global change theory}, booktitle = {The Theory of Ecology}, year = {2011}, pages = {261-281}, publisher = {University of Chicago Press}, organization = {University of Chicago Press}, chapter = {12}, address = {Chicago}, abstract = {Human-caused global changes in ecological drivers, such as carbon dioxide concentrations, climate, and nitrogen deposition, as well as direct human impacts (land use change, species movements and extinctions, etc.) are increasingly recognized as key to understanding contemporary ecosystem dynamics, but a coherent theory of ecological responses to global change has not yet been developed. There are four attributes that characterize phenomena considered under global change (the direct and indirect effects of human actions) that collectively present unique challenges to existing theories. Two of these attributes occur under current conditions: (1) there is natural variation in environmental drivers and system responses within a hierarchy of interacting spatial and temporal scales, and (2) drivers and processes interact across scales such that spatial context and connectivity among spatial units are important to system dynamics; the other two attributes are unique to systems undergoing global change: (3) by definition, global change drivers have an anthropogenic origin that in many cases act outside the realm of natural selection, and (4) these drivers are changing in magnitude, frequency, and direction that result in trajectories of responses that differ from those studied in the past, and are often characterized by threshold behavior and regime shifts. We outline the characteristics of a theory of global change based on propositions derived from the four system attributes, and that draws upon existing theories from a range of sub-disciplines of ecology and other disciplines. This interacting scale theory has the potential to integrate much of our information about global change drivers and responses.}, keywords = {book, chapter, climate, ecological drivers, global change, human-caused, nitrogen}, url = {/files/bibliography/11-032.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and A. K. Knapp} } @proceedings {49981, title = {Plant-soil feedbacks and the reversal of desertification with climate change}, year = {2011}, month = {04/2011}, pages = {292-296}, publisher = {International Rangeland Congress}, address = {Rosario, Argentina}, abstract = {Our objective was to provide a conceptual framework for perennial grass recovery in a series of wet years, which includes both plant-soil feedbacks that increase available water to grasses and effects of precipitation on a sequence of recovery-related processes. We tested hypotheses based on this framework for grasslands and shrublands in the Chihuahuan Desert, the largest desert in North America. Results show that a sequence of 5 wet years following 14 years of variable rainfall increased production in resource conserving ecosystem types greater than predicted based on rainfall alone. The increase in production was primarily by herbaceous plants, which captured water locally to increase plant available water to both existing plants and new recruits. The sequence of wet years allowed a series of linked plant processes to occur that resulted in the establishment and survival of perennial grasses and forbs. We predict that a continued series of wet years will maintain the herbaceous component of these systems, and may act to reverse desertification on degraded shrublands, and to maintain perennial grasslands without management inputs. Degraded shrublands located on slopes susceptible to runoff of water responded linearly to annual precipitation in multiple wet years, and are expected to be resistant to a shift back towards grasslands under a directional increase in precipitation.}, keywords = {Chihuahuan Desert, grasslands, precipitation, regime shift, shrublands}, url = {/files/bibliography/11-017.pdf}, author = {Debra C. Peters and Jin Yao and John P. Anderson and O. E. Sala} } @conference {JRN54509, title = {Responses to climate change in hot desert ecosystems: connecting local to global scales}, booktitle = {96th Ecological Society of America Annual Meeting}, year = {2011}, month = {08/2011}, publisher = {Ecological Society of America}, organization = {Ecological Society of America}, address = {Austin, TX}, abstract = {

The consequences of connectivity in resources, propagules, and information to the interplay between drivers and responses across scales can result in ecological dynamics that are not easily predicted based on local drivers. Three major classes of connectivity events link local ecological dynamics with broader scale drivers. These events differ in initial driver characteristics (intensity, spatial extent, duration), rate of change in response through space, and the relative importance of driver characteristics versus ecological properties and land cover through time. As a result, the impacts of drivers on ecological systems can be synchronized, attenuated or amplified through time and space. Here, I examine how these three classes can interact during the course of a climatic event to result in surprising ecological responses, and a potential state change reversal in the largest desert of North America. A hurricane in 2008 resulted in unusually large amount of summer rainfall, and resulted in a broad-scale recruitment of perennial grasses in degraded shrublands. Successive years of average and below-average rainfall amplified the growth and spatial propagation of grasses via plant-soil feedbacks at the scale of individual plants. Continued interactions across scales are expected to push the system towards a new state codominated by grasses and shrubs. These complex cross-scale dynamics are not unique to this system, and suggest that effective predictions of future dynamics will require a consideration of changing drivers and landuse across scales that include both contiguous and non-adjacent locations.

}, author = {Debra C. Peters} } @article {50054, title = {Climate change: Check the data yourself}, year = {2010}, month = {07/2010}, abstract = {Data on climatic drivers and ecological responses through time tend to be complex and difficult to use by anyone oethr than the individual scientist who collected them. We provide an alternative approach that simplifies complex datasets into derived data products including long-term trends that can be easily understood and interpreted by a broad audience. The result is a book to be published by the USDA publications office, and a website (http://www.ecotrends.info) containing the data with graphical routines that allow easy access and use of the data. Our goal is to allow users to determine for themselves if and where climate change is occurring for sites located across the continental US, Alaska, and Puerto Rico.}, url = {/files/bibliography/10-052.pdf}, author = {Debra C. Peters and William deBuys} } @article {50053, title = {Soil-vegetation-climate interactions in arid landscapes: Effects of the North American monsoon on grass recruitment}, journal = {Journal of Arid Environments}, volume = {74}, year = {2010}, pages = {618-623}, abstract = {

We used a daily time step, multi-layer simulation model of soil water dynamics to integrate effects of soils, vegetation, and climate on the recruitment of Bouteloua eriopoda (black grama), the historically dominant grass in the Chihuahuan Desert. We simulated landscapes at the Jornada ARS-LTER site with heterogeneous soil properties to compare: (1) a grass-dominated landscape in 1858 with the current shrub-dominated landscape (i.e., a change in vegetation structure), and (2) the current shrub-dominated landscape with future landscapes over a range of climate scenarios associated with the North American monsoon (i.e., a change in climate). A historic shift from high productivity grasslands to low productivity shrublands decreased simulated recruitment for most of the site; the amount of reduction depended on location-specific soil properties and changes in production. In some cases, soil properties interacted with vegetation structure: soils high in clay content maintained high recruitment even with a decrease in production. Wetter summers would increase recruitment in all vegetation types. Drier summers below 25\% of current rainfall would decrease recruitment to negligible values (\< 0.03) throughout the landscape. We used our results to identify the conditions where recruitment of B. eriopoda is possible with and without significant modifications to soil and vegetation.

}, keywords = {black grama, Bouteloua eriopoda}, doi = {10.1016/j.jaridenv.2009.09.015}, url = {/files/bibliography/10-014.pdf}, author = {Debra C. Peters and Jeffrey E. Herrick and Curtis H. Monger and C. Huang} } @inbook {50129, title = {Approaches to predicting broad-scale regime shifts using changing pattern-process relationships across scales}, booktitle = {Real World Ecology: Large-scale and long-term case studies and methods}, year = {2009}, month = {2009}, pages = {47-72}, address = {New York}, abstract = {

Understanding and predicting the occurrence of alternative ecosystem states (i.e., regime shifts) at broad scales is a pressing challenge for ecologists given the scope and nature of global change. In many cases, regime shifts at broad-scales are affected by pattern-process relationships across a range of finer scales. However, experimental and analytical methods to examine state changes, such as from perennial grasslands to woodlands, have not been fully developed. We first define and describe the expansion of woody plants into perennial grasslands. Woody plant encroachment has well-documented consequences for local, regional, and global ecology, and takes several forms, from shrub invasion in arid/semiarid grasslands and arctic ecosystems to tree invasion in mesic and alpine grasslands. We then outline a multi-scale experimental approach to examining the key processes influencing woody plant encroachment from fine to broad scales, and describe the application of this approach to the Jornada Basin Agricultural Research Service-Long Term Ecological Research site as a case study. Several questions can be addressed with this approach, such as: how and under what conditions do dynamics and decisions made at fine scales influence dynamics at broader scales? How and under what conditions do broad-scale dynamics overwhelm fine-scale processes to influence landscape patterns? Finally, we discuss analytical techniques for predicting regime shifts and their associated thresholds.

}, keywords = {broad-scale regime, pattern-process}, doi = {10.1007/978-0-387-77942-3_3}, url = {files/bibliography/JRN00523.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and A. K. Knapp and Jeffrey E. Herrick and Curtis H. Monger and Kris Havstad} } @inbook {50130, title = {Boundary dynamics in landscapes}, booktitle = {The Princeton Guide to Ecology}, year = {2009}, month = {August 2009}, pages = {458-463}, publisher = {Princeton University Press}, organization = {Princeton University Press}, chapter = {5}, address = {Princeton, NJ}, abstract = {Landscapes consist of a mosaic of distinct vegetation types and their intervening boundaries with distinct characteristics. Boundaries can exist along abrupt environmental gradients or along gradual changes that are reinforced by feedback mechanisms between plants and soil properties. Boundaries can be defined based on the abundance, spatial distribution, and connectivity of the underlying patches. There are three major types of boundary dynamics that differ in the direction and rate of movement of the boundary in response to climatic fluctuations: stationary, directional, shifting. Future conditions in climate and the disturbance regime, including land use, may fundamentally alter the type of boundary as well as its location and composition through time.}, keywords = {book, boundaries, chapter, landscapes, mosaic, vegetation}, author = {Debra C. Peters and J. R. Gosz and S.L. Collins} } @conference {50132, title = {Indicators of regime shifts in long-term ecological data}, booktitle = {Ecological Society of America Annual Meeting}, year = {2009}, month = {August 2-9, 2009}, pages = {OOS 9-3}, abstract = {Long-term ecological data provide opportunities to examine and compare ecosystem-specific indicators of regime shifts. Our objective was to compare regime shifts from a number of different ecosystem types to determine similarities and differences in indicators. We used long-term data (> 10 years) in the EcoTrends project (http://www.ecotrends.info) from the US Long Term Ecological Research network of sites and from other state and federal agencies in this comparative analysis. Data included both plants and animals from terrestrial, aquatic, marine, and polar systems. In general, similar dynamics were observed across all systems in that abrupt increases in one system component were concurrent with abrupt decreases in another component. Length of time for the regime shift to occur varied across systems. In many cases, interactions among abiotic and biotic processes were important in driving these dynamics, and feedback mechanisms were important in maintaining the new regimes. In some cases, climatic drivers pushed a system past a threshold that provided opportunities for a regime shift, either by a shift in species dominance or by the successful invasion of a new species. This retrospective analysis can be used as a critical step in identifying key processes and conditions for which regime shifts occurred in the past, and to determine the potential for regime shift reversals. However, future analyses of indicators will also need to account for changing climatic conditions and other drivers, including invasive species, which were not part of the historic regime shifts.}, keywords = {ecological data, long-term, regime}, author = {Debra C. Peters} } @conference {50131, title = {Production and biodiversity responses to extreme climatic events across a heterogeneous landscape}, booktitle = {US International Association for Landscape Ecology}, year = {2009}, abstract = {Rising concentrations of atmospheric gases are increasing temperatures globally, but the magnitude and trajectory of localized changes in precipitation are highly uncertain. This uncertainty in climate as a driver results in uncertainty in predictions of future ecosystem dynamics. To reduce this uncertainty, we used 18 years of ecosystem responses that included a series of both dry and wet years to predict future dynamics of a heterogeneous landscape consisting of grasslands and degraded shrublands. We show that long-term (150 year) historical trends in conversion between grasslands and shrublands can be either offset by multi-year increases in precipitation or reinforced by increases in drought. Production and biodiversity responses to extreme climatic events depend on the spatial context of the ecosystem, Although historical dynamics provide insights to the future, ecological response data collected under alternative climatic conditions are needed to account for uncertainty in the direction and magnitude of global change drivers in the future.}, keywords = {atmospheric, biodiversity, climatic, ecology, heterogeneous, temperatures}, author = {Debra C. Peters and Jin Yao and O. E. Sala} } @conference {50133, title = {Shifts in species dominance at a biome transition zone: Importance of asymmetric competition to long-term trends}, booktitle = {2009 LTER All Scientist Meeting}, year = {2009}, abstract = {Landscapes at the Sevilleta LTER site are dominated or codominated by two perennial grasses from different biomes, Bouteloua eriopoda (black grama) from the Chihuahuan Desert and B. gracilis (blue grama) from the shortgrass steppe, and the Chihuahuan Desert shrub Larrea tridentata (creosotebush). We used a long-term removal study to examine inter-specific interactions between these dominant species, and to determine which species would eventually dominate following the removal of the others. Plants of the dominant species were removed from 5 3m x 4m plots in 1995 at five sites that were either dominated by one of the three species (blue grama grasslands, black grama grasslands, cresootebush shrublands) or at ecotones codominated by two species (blue grama/black grama; black grama/creosotebush). Plant cover is estimated annually, and removals have been conducted annually since that time. Results show that removal of black grama has little effect on cover of blue grama whereas removal of blue grama or creosotebush results in marked increases in cover of black grama. Our results show that competition between black grama and either blue grama or creosotebush is asymmetric. These interactions suggest that black grama dominance may be reduced in the future under climate conditions that favor growth of either blue grama or creosotebush since these species can outcompete black grama. Landscape patterns associated with soil texture can also be explained by these interspecific interactions for soil water in this semiarid environment.}, keywords = {asymmetric, B. gracilis, black grama, Bouteloua eriopoda, creosotebush, LTER, Sevilleta}, author = {Debra C. Peters and Jin Yao} } @article {50255, title = {Ecology in a connect world: A vision for a "network of networks"}, journal = {Frontiers in Ecology and the Environment}, volume = {6}, number = {5}, year = {2008}, month = {06/2008}, pages = {227}, abstract = {

This special issue addresses the importance of connectivity in driving ecosystem dynamics. Connectivity is defined as the transfer of materials by wind, water, humans, and animals. Although it is well-recognized that we live in a connected world, it is less well-appreciated that these interconnections can determine ecosystem dyamics across a range of spatial and temporal scales, and in particular at regional to continental scales. The six papers in this issue provide examples of research questions and approaches necessary for conducting research at the continental scale. These papers address questions such as: what are the consequences of connectivity, not only at the global scale, but also at relevant continental, regional, and local scales? how do we identify connections among non-adjacent and seemingly disconnected locations, to both minimize the element of surprise and mitigate or avert potential impacts? how do we adjust our thinking about ecological systems and modify our sampling strategies to account for the fluxes and flows of materials among locations? New insights are discussed for five topics (spread of invasive species and infectious diseases, climate change and aquatic systems, climate change and coastal systems, climatic and societal gradients across landscapes, climate change and terrestrial systems) that are critical elements of our connected world, now and in the future.

}, keywords = {ecosystem dynamics, fluxes}, url = {/files/bibliography/08-010.pdf}, author = {Debra C. Peters} } @article {50254, title = {Living in an increasingly connected world: a framework for continental-scale environmental science}, journal = {Frontiers in Ecology and the Environment}, volume = {6}, number = {5}, year = {2008}, month = {June 2008}, pages = {229-237}, abstract = {

The global environment is changing rapidly through processes that act at multiple spatial and temporal scales. It is now clear that local processes can affect broader-scale ecological dynamics, and that broad-scale drivers may at times overwhelm local patterns and processes. Understanding these cross-scale interactions requires a conceptual framework to predict continental-scale ecosystem dynamics based on connectivity in material and information flow across scales. In this paper, we (1) discuss a multi-scale conceptual framework, including the key drivers and consequences of ecological connectivity acting across spatial and temporal scales, (2) provide a series of testable hypotheses, predictions, and an approach derived from this conceptual framework, and (3) propose the development of a network of networks largely taking advantage of existing research facilities and cyberinfrastructure to address these hypotheses. This framework and associated research infrastructure based on connectivity across scales will uniquely enable our understanding and enable us to better forecast global environmental change at multiple spatial scales, from local research sites to regions and continents.

}, keywords = {article, continental-scale, environment, journal, spatial, temporal}, doi = {10.1890/070098}, url = {/files/bibliography/08-011.pdf}, author = {Debra C. Peters and Peter M. Groffman and K.J. Nadelhoffer and N.B. Grimm and S.L. Collins and Michener, W.K. and Huston, M.A.} } @conference {50253, title = {Perspectives on global change theory}, booktitle = {Ecological Society of America Abstracts}, volume = {SYMP 2-7}, year = {2008}, month = {August 3, 2008}, abstract = {Global changes in ecological drivers, such as CO2 concentrations, climate, and nitrogen deposition, are increasingly recognized as key to understanding contemporary ecosystem dynamics, but a coherent theory of global change has not yet been developed. We outline the characteristics of a theory of global change that draws upon other theories from a range of sub-disciplines, including population biology, landscape ecology, and Earth system sciences. The theory is based on the following propositions: (1) global scale patterns can be understood via the hierarchy of interacting processes at finer scales, from plants to landscapes and regions, and fine-scale patterns often cannot be understood without knowledge of global processes; (2) dynamics at any location on the globe are affected to varying degrees by transfer processes that connect adjacent as well as distant locations, (3) transfer processes (wind, water, animals, humans) connect locations via the movement of organisms, materials, disturbance, and information, (4) spatial heterogeneity (i.e., pattern) determines how drivers and transfer processes interact across scales, and (5) the relative importance of fine- or broad-scale pattern-process relationships can vary through time, and alternate as the dominant factors controlling system dynamics. We develop the basis for this theory and provide supporting evidence for it. This multiple, interacting scale theory has the potential to integrate much of our information about global change drivers and responses.}, keywords = {abstract, abstracts, climate, ecological, global, nitrogen}, author = {Debra C. Peters and Brandon T Bestelmeyer and A. K. Knapp} } @inbook {50257, title = {The Role of Disturbances in Shortgrass Steppe Community and Ecosystem Dynamics}, booktitle = {Long-Term Ecological Research in the Shortgrass Steppe}, year = {2008}, month = {September 2008}, pages = {84-118}, abstract = {The disturbance regime of shortgrass steppe ecosystems consists of a number of different types of disturbances operating over a range of spatial and temporal scales. Each disturbance type has its own set of characteristics including size, frequency of occurrence, intensity, and location by soil texture, topographic position, and grazing intensity by cattle. These characteristics result in different short-term, localized effects on plant as well as long-term, broad-scale effects as the disturbances accumulate through time. Although successional studies have been conducted in these grasslands for over a century, our understanding of the role of different kinds of disturbances in generating and maintaining patterns in vegetation and species dominance in shortgrass ecosystems has developed only since the 1980{\textquoteright}s. Our current view of the role of disturbance is a dynamic one where the recovery of vegetation depends upon interactions among disturbance characteristics and the life history traits of plants. This gap dynamics conceptualization provides an alternative view of vegetation dynamics compared to traditional successional models based on Clements. Much of the recent work on disturbances in the shortgrass steppe has focused on the relationships between disturbance characteristics and plant life history traits in order to test these different models. This chapter describes the various alternative models, and summarizes the literature on the disturbance regime of shortgrass steppe ecosystems and the responses of vegetation and soils following different kinds of disturbances.}, author = {Debra C. Peters and W. K. Lauenroth and Ingrid C. Burke} } @inbook {50256, title = {Simulation of disturbances and recovery in shortgrass steppe plant communities}, booktitle = {Ecology of the Shortgrass Steepe: A long-term perspective}, year = {2008}, month = {September 2008}, pages = {119-131}, publisher = {Oxford Press}, organization = {Oxford Press}, address = {New York}, abstract = {The objective of this chapter was to evaluate the importance of gap dynamics concepts of succession for understanding shortgrass plant community recovery following disturbances. A gap dynamics approach focuses on individual plants, and the interactions between disturbance characteristics and plant life history traits in explaining successional patterns. We developed a gap dynamics model for shortgrass steppe plant communities (STEPPE) based upon the conceptual and modeling framework provided by forest models, modifying it to represent Great Plains grasslands. We used STEPPE in several capacities: (1) to synthesize and integrate existing knowledge to improve our understanding of recovery processes following disturbance; (2) to identify key processes limiting recovery; and (3) to predict long- term recovery dynamics for different climate and disturbance characteristics, in particular soil texture and disturbance size. Our analyses show that seed dispersal is a key process limiting recovery of the dominant species, blue grama, across a range of disturbance sizes. Our simulation results also indicate the importance of soil properties, especially silt content, to recovery rates of blue grama, and the greater importance of seedling establishment compared to seedling growth; however these hypotheses have yet to be tested in the field.}, keywords = {gap dynamics, recovery, shorgrass plant community}, author = {Debra C. Peters and W. K. Lauenroth} } @article {50370, title = {Cascading Events in Linked Ecological and Socio-Economic Systems}, journal = {Frontiers in Ecology and the Environment}, volume = {5}, number = {4}, year = {2007}, month = {May 2007}, pages = {221-224}, abstract = {

Cascading events that start at small spatial scales and propagate nonlinearly through time to influence larger areas often have major impacts on ecosystem goods and services. These events, such as wildfires and hurricanes, are increasing in frequency and magnitude as systems become increasingly connected through globalization processes. We need to improve our understanding of these events in order to predict their occurrence, to minimize potential impacts, and to allow for strategic recovery. In this workshop held during the ESA meeting in Merida, Mexico on 2006 January 11, we synthesized information about cascading events for systems located throughout the Americas. Our discussions included diverse examples of cascading events that share a common feature: linked ecological and human processes across scales often drive these events. In this era of globalization, we recommend studies that explicitly examine connections across scales, and the role of connectivity among non-contiguous areas as well as contiguous areas.

}, keywords = {ecological, nonlinearly, socio economic}, doi = {10.1890/1540-9295(2007)5[221:CEILEA]2.0.CO;2}, url = {/files/bibliography/07-011.pdf}, author = {Debra C. Peters and O. E. Sala and C.D. Allen and Covich, A. and M. Brunson} } @article {50368, title = {Cross-scale interactions and changing pattern-process relationships: Consequences for system dynamics}, journal = {Ecosystems}, volume = {10}, year = {2007}, month = {August 2007}, pages = {790-796}, abstract = {Cross-scale interactions occur either when fine-scale processes influence a broad spatial extent or a long time period, or when broad-scale drivers interact with fine-scale processes to determine system dynamics. Cross-scale interactions are increasing recognized as having important influences on ecosystem processes, yet, they pose formidable challenges for understanding and forecasting ecosystem dynamics. In this introduction to the special feature, \‘Cross-scale interactions and pattern-process relations\”, we provide a synthetic framework for understanding the causes and consequences of cross-scale interactions. Our framework focuses on the importance of transfer processes and spatial heterogeneity at intermediate scales in linking fine- and broad-scale patterns and processes. Transfer processes and spatial heterogeneity can either amplify or attenuate system response to broad-scale patterns and processes. Providing a framework to explain cross-scale interactions is an important step in improving our understanding and ability to predict the impacts of propagating events and to ameliorate these impacts through proactive measures.}, keywords = {ecological surprises, landscape ecology, propagating events, spatial heterogeneity, tansfer processes}, doi = {10.1007/s10021-007-9055-6}, url = {/files/bibliography/07-030.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and M.G. Turner} } @conference {50369, title = {Soil-vegetation feedbacks in dynamic landscapes: Implications for restoration}, booktitle = {Ecological Society of America Abstracts}, year = {2007}, month = {August 5-10, 200}, pages = {PS 45-80}, address = {San Jose, CA}, abstract = {State changes from perennial grasslands to shrub-dominated systems characterize much of the arid regions of the world, including the American Southwest. Where this conversion is associated with a change in soil surface texture, near-surface water availability can be increased or reduced with important consequences for restoration of perennial grasses. Loss of soil from one area results in deposition in downslope or downwind areas. Little is known about these spatial connections, and how erosion-deposition patterns influence seedling establishment and recovery of perennial grasses. Our objective was to evaluate how soil erosion-associated changes in surface soil texture influence the probability of seedling establishment of the perennial grass, black grama, across a range of initial soil textures. We used a simulation model of daily soil water dynamics (SOILWAT) to simulate recruitment probabilities of this species for the variation in initial soil texture found at the Jornada Basin ARS-LTER site in southern New Mexico. Vegetation and landform maps combined with soils, vegetation, and weather data were used to parameterize the model. Simulated recruitment probabilities were generally higher where near-surface water holding capacity was higher. However, in some cases deposition of small amounts of coarse-textured material (lower water holding capacity) on a relatively fine-textured (higher water holding capacity) site increased establishment due to reduced evaporative losses. We used a wind model to determine spatial patterns in soil loss and deposition at the landscape scale, and displayed our recruitment results for the Jornada Basin. Locations with the largest changes in soil surface texture as a result of wind had the largest changes in recruitment probabilities. Our results show that wind erosion and deposition patterns have strong influences on patterns in seedling establishment.}, keywords = {perennial, shrub-dominated, soil vegetation}, author = {Debra C. Peters and Jeffrey E. Herrick and Curtis H. Monger and Gregory S. Okin} } @inbook {50371, title = {Spatial nonlinearities: Cascading effects in the earth system}, booktitle = {Terrestrial Ecosystems in a Changing World}, year = {2007}, month = {2007}, pages = {165-174}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {Berlin, Germany}, abstract = {Nonlinear interactions and feedbacks associated with thresholds through time and across space are common features of biological, physical and materials systems. These spatial nonlinearities generate surprising behavior where dynamics at one scale cannot be easily predicted based on information obtained at finer or broader scales. These cascading effects often result in severe consequences for the environment and human welfare (i.e., catastrophes) that are expected to be particularly important under conditions of changes in climate and land use. In this chapter, we illustrate the usefulness of a general conceptual and mathematical framework for understanding and forecasting spatially nonlinear responses to global change. This framework includes cross-scale interactions, threshold behavior and feedback mechanisms. We focus on spatial nonlinearities produced by fine-scale processes that cascade through time and across space to influence broad spatial extents. Here we describe the spread of catastrophic events in the context of our cross-disciplinary framework using examples from biology (wildfires, desertification, infectious diseases) and engineering (structural failures) and discuss the consequences of applying these ideas to forecasting future dynamics under a changing global environment.}, keywords = {desertification, nonlinearities, wildfires}, author = {Debra C. Peters and R.A. Pielke and Brandon T Bestelmeyer and C.D. Allen and Seth M. Munson and Kris Havstad}, editor = {J. Canadell and D.E. Pataki and Pitelka, L.} } @conference {50484, title = {Changes in Perennial Grass Recruitment From 1858 to Present Following Woody Plant Invasion}, booktitle = {91st Ecological Society of America Annual Meeting}, year = {2006}, month = {August 6-11, 200}, pages = {99}, address = {Memphis, TN}, abstract = {Desert ecosystems of the American Southwest have experienced dramatic changes in vegetation structure and soil properties over the past several centuries with the expansion of native woody plants. This conversion from perennial grasslands to shrublands is often difficult to reverse as a result of soil degradation and low grass seed availability. Additional recruitment processes that can limit the return of grasses are seed germination and seedling establishment, processes that are affected by both soil properties and vegetation structure. Our objective was to examine and compare the probability of recruitment of the perennial grass, Bouteloua eriopoda (black grama), in 1858 and at present using the simulation model of daily soil water dynamics. We used the model to simulate recruitment probabilities of black grama for the variation in conditions found at the Jornada Basin ARS-LTER site in southern New Mexico. Vegetation and soils maps for both time periods and historical weather data were used to parameterize the model. In general, simulated recruitment probabilities were higher in 1858 when the Jornada was dominated by grasslands compared with the present, shrub-dominated system. Because recruitment of black grama is nonlinearly related to silt content of the soil and to aboveground plant cover, these changes in recruitment probabilities were dependent on location-specific changes in soil properties and vegetation cover. Our results were used to identify the locations and conditions where recruitment of black grama is still possible; these areas can then be targeted for remediation efforts. We also identified the locations where remediation efforts of this grass species will fail without significant modifications to soil properties and vegetation cover. This approach to stratifying landscapes by recruitment potential can be used for other invasive species.}, keywords = {1858, grasslands and shrublands, modeling, perennial grass, Present, recruitment, woody plant}, author = {Debra C. Peters and Curtis H. Monger and Jeffrey E. Herrick} } @article {50483, title = {Disentangling complex landscapes: new insights into arid and semiarid system dynamics}, journal = {BioScience}, volume = {56}, number = {6}, year = {2006}, month = {June 2006}, pages = {491-501}, abstract = {

Although desertification is a global phenomenon and numerous studies have provided information on dynamics at specific sites, spatial and temporal variation in response to desertification have led to alternative, and often controversial, hypotheses about the key factors that determine these dynamics. We present a new research framework that includes five interacting elements to explain these dynamics: (1) historical legacies, environmental driving variables, (3) a soil-geomorphic template, (4) horizontal and vertical transport vectors, and (5) redistribution of resources within and among spatial units. We offer a six-step operational approach that is applicable to many landscapes, and illustrate its utility for understanding present-day landscape organization, forecasting future dynamics, and making effective management decisions.

}, keywords = {alternative states, cross-scale interactions, desertification, feedbacks and thresholds, nonlinear dynamics}, doi = {10.1641/0006-3568(2006)56[491:DCLNII]2.0.CO;2}, url = {/files/bibliography/06-021.pdf}, author = {Debra C. Peters and Brandon T Bestelmeyer and Jeffrey E. Herrick and E.L. Fredrickson and Curtis H. Monger and Kris Havstad} } @inbook {50486, title = {A Framework and Methods for Simplifying Complex Landscapes to Reduce Uncertainty in Predictions}, booktitle = {Scaling and Uncertainty Analysis in Ecology: Methods and Applications}, year = {2006}, month = {2006}, pages = {131-146}, publisher = {Springer, Dordrecht}, organization = {Springer, Dordrecht}, address = {The Netherlands}, abstract = {

Many of our most pressing ecological problems, such as the conservation of biodiversity, spread of invasive species, patterns in carbon sequestration, and impacts of disturbances (e.g., fire) must be addressed at the landscape scale (see Law et al., Chapter 9, Groffman et al., Chapter 10, Urban et al., Chapter 13). However, much of our information about these problems comes from plot-scale studies that must be extrapolated to the landscape. Because landscapes are complex, this extrapolation is not always straightforward or easy to accomplish (Turner et al. 1989a, Wu and Li, Chapter 2, Braford and Reynolds,Chapter 6). Landscape complexity results from the processes, factors, and their interactions that occur across a range of spatial and temporal scales. The problem is further complicated by the presence of contagious or neighborhood processes that connect different parts of a landscape. Dispersal of seeds by wind or animals, fire, and erosion and deposition of soil and nutrients by wind and water are examples of spatial or contagious processes that influence ecosystem dynamics. Landscape complexity makes it difficult to understand and predict ecosystem dynamics across spatial scales with high levels of confidence or certainty. Our goal is to develop a conceptual framework and operational approach to simplifying complex landscapes in order to minimize both prediction errors and costs associated with measurement, analysis, and prediction.

}, keywords = {ecosystems, linear, spatial temp oral heterogeneous}, doi = {10.1007/1-4020-4663-4_7}, url = {/files/bibliography/06-051.pdf}, author = {Debra C. Peters and Jin Yao and L. Huenneke and Kris Havstad and Jeffrey E. Herrick and A. Rango and W. H. Schlesinger} } @inbook {50490, title = {Future Directions in Jornada Research: Applying an Interactive Landscape Model to Solve Problems}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {369-386}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {18}, address = {New York, NY}, abstract = {In this book chapter, we propose a new model of arid and semiarid landscapes that focuses explicitly on the processes and properties that generate spatial variation in ecosystem dynamics. We are specifically interested in three interrelated aspects of landscapes: (1) feedbacks among plants, animals, and soils generated from interactions among biotic processes, a heterogeneous physical template, and the disturbance regime across a range of spatial and temporal scales, (2) neighborhood or contagious processes that generate fluxes and flows within and among spatial units, and (3) the landscape context and the condition of the study area of interest relative to its surroundings that modifies the transfers of materials. We first describe our spatially interactive model and compare it to previous models then introduce an approach to identify the landscape locations where spatial processes and information are needed in order to understand and predict ecosystem dynamics. The local, regional, and global implications of our interactive landscape model are also discussed.}, keywords = {Chihuahuan Desert, Jornada Basin, LTER, synthesis book}, url = {/files/bibliography/06-069.pdf}, author = {Debra C. Peters and W. H. Schlesinger and Jeffrey E. Herrick and L. Huenneke and Kris Havstad}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @article {50489, title = {Integrating patch and boundary dynamics to understand and predict biotic transitions at multiple scales}, journal = {Landscape Ecology}, volume = {21}, year = {2006}, month = {2006}, pages = {19-33}, abstract = {

Human modification of landscapes superimposed upon natural environmental heterogeneity is resulting in an increase in the numbers and types of ecological patches and their intervening boundaries (i.e., biotic transitions). In this paper, we develop an operational framework for understanding and predicting dynamics of these biotic transitions for a range of environmental conditions across multiple spatial scales. We define biotic transitions as the boundary and the neighboring states, a more general definition than typically denoted by the terms boundary, ecotone, edge or gradient. In our framework, we use concepts of patch dynamics to understand the structural and functional properties of biotic transitions, and to predict changes in boundaries through time and across space. We develop testable hypotheses, and illustrate the utility of our approach with examples from arid and semiarid ecosystems. Our framework provides new insights and predictions as to how landscapes will respond to future changes in climate and other environmental drivers.

}, keywords = {Directional transitions, ecotones, Positive feedbacks, Shifting transitions, Stationary transitions}, doi = {10.1007/s10980-005-1063-3}, url = {/files/bibliography/06-014.pdf}, author = {Debra C. Peters and J. R. Gosz and Pockman, W.T. and Small, E.E. and Paramenter, R.E. and S.L. Collins and E. Muldavin} } @article {50482, title = {Nonlinear dynamics in arid and semi-arid systems: Interactions among drivers and processes across scales}, journal = {Journal of Arid Environments}, volume = {65}, year = {2006}, month = {April 1, 2006}, pages = {196-206}, abstract = {

We discuss a new conceptual framework for arid and semiarid systems that accounts for nonlinear dynamics and cross scale interactions in explaining landscape patterns and dynamics. Our framework includes a spatial and temporal hierarchy, and five key interacting components that connect scales of the hierarchy: (1) historical legacies that include climate, disturbance, and management regimes, (2) dynamic template of patterns in ecological variables and spatial context, (3) vertical and horizontal transport processes (fluvial, aeolian, animal), (4) the rate, direction, and amount of resource redistribution between high and low resource areas, and (5) feedbacks among plants, animals, and soils. We illustrate how this framework can be used to understand, forecast, and manage ecological systems that exhibit nonlinear dynamics across a range of spatial and temporal scales. This paper provides the foundation for a series of papers from the Jornada Experimental Range ARS-LTER research site in southern New Mexico, USA that support this new conceptual framework.

}, keywords = {across scales, arid, drivers, dynamics, nonlinear, semiarid}, doi = {10.1016/j.jaridenv.2005.05.010}, url = {/files/bibliography/06-007.pdf}, author = {Debra C. Peters and Kris Havstad} } @inbook {50487, title = {Plant Communities in the Jornada Basin: The Dynamic Landscape}, booktitle = {Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site}, year = {2006}, month = {July 1, 2006}, pages = {211-231}, publisher = {Oxford University Press}, organization = {Oxford University Press}, chapter = {10}, address = {New York, NY}, abstract = {Plant communities of the Jornada Basin LTER are characteristic of the northern Chihuahuan Desert, both in structure and dynamics. Five major vegetation types are often distinguished that differ in plant species cover and composition, as well as other factors, such as animal populations, soil properties, and elevation. Similar to many other parts of the Chihuahuan Desert, these plant communities have experienced major shifts in vegetation over the past 50-150 years. The most dramatic changes in vegetation have occurred as a result of woody plant encroachment into perennial grasslands. In this chapter, we describe the characteristics of each vegetation type and the documented changes in each type at the Jornada. We also discuss the key drivers (small and larger animal activity, drought, fire, and directional changes in climate) influencing these vegetation dynamics.}, keywords = {Chihuahuan Desert, Jornada Basin, LTER, synthesis book}, url = {/files/bibliography/06-061.pdf}, author = {Debra C. Peters and Gibbens, Robert P.}, editor = {Kris Havstad and L. Huenneke and W. H. Schlesinger} } @article {50488, title = {Spatial variation in remnant grasses after a grassland-to-shrubland state change: Implications for restoration}, journal = {Rangeland Ecology and Management}, volume = {59}, year = {2006}, month = {July 2006}, pages = {343-350}, abstract = {

Around the world rangelands that have been degraded, such as historical desert grasslands now dominated by woody shrubs, are resistant to restoration efforts. The goal of this descriptive research was to examine the potential for black grama (Bouteloua eriopoda [Torr.] Torr.) recovery by remnant plants in a degraded area as a function of plant location across a landscape. Our objectives were 1) to document the historical dominant vegetation as a perennial grassland and determine broad-scale changes in dominance through time and 2) to examine fine-scale patterns of black grama presence and basal area with respect to microenvironmental conditions that indicate the landscape positions favorable for restoration. Historical vegetation maps starting in 1858, a field survey in 2002{\textendash}2003 of the location of all individual black grama plants in a 29-ha area, and spatial data layers in a geographic information system were used to address these objectives. Upland grasses, including black grama, dominated the study site in 1858, although tarbush (Flourensia cernua DC.) was the dominant species by 1915, and creosotebush (Larrea tridentata [DC.] Cov.) is the current dominant. A total of 3 334 black grama plants were found for an average density of 0.01 plants{\textperiodcentered}m-2. High spatial variation was found in the occurrence and basal area of black grama plants that was related to water availability rather than livestock grazing: most plants were found in or adjacent to an arroyo (67\%), at a northern aspect (47\%), and outside experimental exclosures established in 1930 (43\%). Largest average basal areas were found in the livestock exclosure, and in general, average basal area was not related with aspect or canopy microsite. These remnant plants can be used as propagule sources in restoration efforts, and information on microsite conditions for black grama survival can be used to improve restoration potential for similar sites.

}, keywords = {Bouteloua eriopoda, Flourensia cernua, Larrea tridentata, perennial grasslands, shrub invasion}, doi = {10.2111/05-202R1.1}, url = {/files/bibliography/06-028.pdf}, author = {Debra C. Peters and Mariotto, I. and Kris Havstad and Murray, L.M.} } @article {50485, title = {Woody Plant Invasion at a Semi-arid Transition Zone: Importance of Ecosystem Type to Colonization and Patch Expansion}, journal = {Journal of Vegetation Science}, volume = {17}, year = {2006}, note = {Duplicate of ARIS $\#$ 182512}, month = {June 15, 2006}, pages = {389-396}, abstract = {Our objective was to evaluate how patterns in colonization and patch expansion of an invasive woody plant, Larrea tridentata (creosotebush) differ between two grassland ecosystems at a biome transition zone. We sampled frequency of occurrence, height, and surface area of saplings (n=134) and patches of adult plants (n=247) of creosotebush within a mosaic of ecosystems dominated either by the Chihuahuan Desert species, black grama, or the shortgrass steppe species, blue grama, located within 1 km of the creosotebush-dominated ecosystem. Distances between patches and patch area were used to estimate connectivity and propagule pressure. Sapling height and distance to the creosotebush dominated ecosystem were used to estimate patterns in dispersal. Our results show that creosotebush saplings (<1\%) and patches of adults (15\%) occur less frequently in black grama than blue grama-dominated ecosystems. Propagule pressure did not differ with distance from the core creosotebush ecosystem. Evidence was found for both local and long distance dispersal. We conclude that spatial variation in creosotebush saplings and adults at this biome transition zone is related to the different susceptibilities to invasion by the two grassland ecosystems. The persistence of grasslands at this site despite region-wide expansion by creosotebush may be related to the spatial distribution of blue grama-dominated ecosystems that resist or deter invasion by this species.}, keywords = {colonization, ecosystem, semi-arid, transition, woody}, url = {/files/bibliography/06-024.pdf}, author = {Debra C. Peters and Jin Yao and J. R. Gosz} } @conference {50589, title = {Cross Scale Interactions and Spatial Nonlinearities: An Interdisciplinary Framework}, booktitle = {Ecological Society of America 90th Annual Meeting}, year = {2005}, month = {August 7-12, 200}, pages = {504}, address = {Montreal, Quebec, CANADA}, abstract = {Thresholds caused by nonlinear interactions and feedbacks across spatial scales are common features of ecological and physical systems. Spatial nonlinearities (i.e., acceleration or deceleration in the rate of change as the spatial extent expands) challenge the ability of ecologists to understand and predict system behavior at one scale based on information obtained at finer or broader scales. Thus, cross-scale interactions often result in {\textquotedblleft}surprises{\textquotedblright} with severe consequences for the environment (e.g., wildfire, pest outbreaks, state changes) and human welfare (e.g., spread of infectious diseases). Alternatively, cross scale interactions may be beneficial, such as accelerated recovery of vegetation following fire. In both cases, fine scale processes propagate nonlinearly to have unexpected effects at broader spatial scales. In many cases, climate variability and its effects on ecosystems, is a mechanism for cross-scale synchronization of ecosystem pattern and process.Identification of the key processes generating the nonlinear behavior is often problematic. We present a conceptual framework for understanding and forecasting events that result from cross scale interactions. We provide support for our framework using both historical (the Dust Bowl) and current examples (wildfires, invasive species). This paper provides the introduction for a series of papers on the importance of cross scale interactions to the dynamics of a variety of ecological systems.}, keywords = {ecological, nonlinear, sptaial, thresholds}, author = {Debra C. Peters and Brandon T Bestelmeyer} } @article {50700, title = {Cross-scale interactions, nonlinearities, and forecasting catastrophic events}, journal = {Proceedings of the National Academy of Sciences}, volume = {101}, number = {42}, year = {2004}, month = {October 19, 2004}, pages = {15130-15135}, abstract = {

Catastrophic events share characteristic nonlinear behaviors that are often generated by cross-scale interactions and feedbacks among system elements. These events result in surprises that cannot be easily predicted based on information obtained at a single scale. Progress to date on catastrophic events has focused on one of two areas: (1) nonlinear dynamics through time without an explicit consideration of spatial connectivity, and (2) spatial connectivity and the spread of contagious processes without a consideration of cross scale interactions and feedbacks. These approaches have rarely ventured beyond traditional disciplinary boundaries. We provide an interdisciplinary, conceptual and general mathematical framework for understanding and forecasting nonlinear dynamics through time and across space. We illustrate the generality and utility of our approach using new data and a recasting of published data from ecology (wildfires, desertification), epidemiology (infectious diseases) and engineering (structural failures). We show that decisions that minimize the likelihood of catastrophic events must be based on cross-scale interactions, and such decisions will often be counter-intuitive. Given the continuing challenges associated with global change, approaches that cross disciplinary boundaries to include interactions and feedbacks at multiple scales are needed to increase our ability to predict catastrophic events and to develop strategies for minimizing their occurrence and impacts. Our framework is an important step in developing predictive tools and designing new experiments to examine cross-scale interactions.

}, keywords = {catastrophic events, cross-scale interactions, forecasting, nonlinearities}, doi = {10.1073/pnas.0403822101}, url = {files/bibliography/JRN00406.pdf}, author = {Debra C. Peters and R.A. Pielke and Brandon T Bestelmeyer and C.D. Allen and Seth M. Munson and Kris Havstad} } @article {50705, title = {Insights to invasive species dynamics from desertification studies}, journal = {Weed Technology}, volume = {18}, year = {2004}, month = {August 1, 2004}, pages = {1221-1225}, abstract = {

The objective of this paper is to provide insights into exotic and native invasive species dynamics using a conceptual model developed from the long history of research on native woody plant invasion into perennial grasslands. We first describe our new conceptual model that focuses on landscape characteristics (spatial configuration and connectivity) interacting with environmental drivers and biotic processes across multiple scales. We then provide support for the model using a long-term dataset from southern New Mexico. Finally, we discuss new insights this model has to offer for understanding, predicting, and managing exotic invasive species dynamics.

}, keywords = {conceptual model, exotic, invasive species, managing, native, perennial grasslands, predicting, woody plant invasion}, doi = {10.1614/0890-037X(2004)018[1221:ITISDF]2.0.CO;2}, url = {files/bibliography/JRN00409.pdf}, author = {Debra C. Peters and Jin Yao and Kris Havstad} } @conference {50703, title = {Introducing the International Long-Term Ecological Research (ILTER) network}, booktitle = {LAND Open Science Conference}, year = {2004}, month = {December 2, 2004}, pages = {62}, address = {Morelia, Mexico}, abstract = {Long-term, broad-scope research is important for revealing trends that cannot be detected with traditional short-term, small-scale research. Global scientific interest in developing networks of long-term ecological research programs is expanding rapidly, acknowledging the utility of this model for research in assessing and resolving complex environmental issues. Through the International Long-Term Ecological Research Network (ILTER), investigators around the globe exchange expertise, develop and share knowledge and information resources and research methods, thus integrating their research and placing it in a global context. This poster will offer an introduction to the methods used to develop and grow the ILTER Network, address the impact of global-scale science, and inspire discussion about these topics.}, author = {Debra C. Peters and Sprott, P. and French, C.} } @conference {50701, title = {Nonlinear dynamics in arid systems: interactions among drivers and processes across scales}, booktitle = {Sixth Symposium on the Natural Resources of the Chihuahuan Desert Region}, year = {2004}, month = {October 15, 2004}, pages = {38}, address = {Alpine, TX}, abstract = {Conversion from perennial grasslands to shrub-dominated systems has occurred globally in arid and semiarid systems and regionally in the Chihuahuan Desert over the past 100-150 years. Broad-scale drivers, such as grazing and extreme drought, are often invoked to explain shrub invasion dynamics. We use long-term, spatially explicit data to show that these drivers are frequently insufficient to explain patterns in shrub invasion and grass persistence at the landscape scale. At the Jornada Experimental Range, we are developing a new conceptual framework to explain high temporal and spatial variation in landscape patterns and dynamics. Our framework focuses on five key aspects of these systems: (1) threshold behavior, (2) spatially contagious processes, (3) landscape context, (4) feedbacks between biotic and abiotic processes at multiple scales, and (5) landscape legacies. We show how accounting for these key aspects of system behavior can explain nonlinear dynamics across spatial and temporal scales. This talk provides the background for the remaining talks in the special session {\textquotedblleft}Landscape linkages and cross-scale interactions in the Chihuahuan Desert.{\textquotedblright}}, keywords = {arid systems, broad-scale drivers, Chihuahuan Desert, drivers, feedbacks, interactions, landscape contest, nonlinear dynamics, processes, scales, spatially contagious processes, threshold behavior}, author = {Debra C. Peters and Kris Havstad} } @article {50707, title = {Selection of models of invasive species dynamics}, journal = {Weed Technology}, volume = {18}, year = {2004}, month = {August 1, 2004}, pages = {1236-1239}, abstract = {

Mathematical and process-based simulation models are powerful tools for synthesizing information about invasive species. However, there are a number of different types of models, ranging from simple to complex that can be selected for any given application. In this article, a model classification framework of three types of models is applied to studies of invasive species that allows the objective selection of a model type on the basis of its ability to capture key processes and dynamics, yet minimize the errors in prediction. Model selection is illustrated using a series of increasingly complex models.

}, keywords = {biotic, dynamics, environmental, invasive, landscape, Nonspatial models, spatially explicit models, spatially implicit models.}, doi = {10.1614/0890-037X(2004)018[1236:SOMOIS]2.0.CO;2}, url = {files/bibliography/JRN00420.pdf}, author = {Debra C. Peters} } @conference {50706, title = {Spatial nonlinearities and cascading effects across landscapes in the Earth system}, booktitle = {LAND Open Science Conference}, year = {2004}, month = {December 2, 2004}, pages = {50}, address = {Morelia, Mexico}, abstract = {Our objective was to develop and apply a conceptual framework to examine the importance and generality of spatial nonlinearities in the dynamics of the Earth system. Atmosphere-biosphere interactions are increasingly recognized as important to local ecosystem dynamics as well as to the global carbon cycle. However, the multi-scale nature of these interactions and their feedbacks are less well-known and poorly understood. This lack of understanding leads to ecological {\textquoteright}surprises{\textquoteright} associated with nonlinear ecosystem responses to broad-scale forcing functions and feedbacks to the atmosphere. Our lack of understanding about these nonlinear dynamics cascading spatially across landscapes (i.e., spatial nonlinearities) severely limits our ability to identify the conditions leading to catastrophic events, as well as the impacts of these events on local and regional economies, conservation of species, ecosystem services, and balances in atmospheric gases. We examine these spatial nonlinearities in the dynamics of the Earth system in the context of interactions and feedbacks between atmospheric processes and ecosystem structure and dynamics across a range of spatial and temporal scales. We surmise that changes in spatial pattern of ecosystems over time, especially at the landscape scale, due to local ecological processes mediate the influence of atmospheric processes operating at broader scales. Rapid shifts in rates of atmospheric processes across values of spatial metrics create thresholds in time and feedbacks to spatial structure of the landscape with subsequent feedbacks to the atmosphere. Thus, small changes in spatial pattern can determine if a forcing function is amplified or attenuated across a landscape. It is only by accounting for these complex, multi-scale feedbacks between local ecological processes, landscape structure, and the atmosphere that can we begin to understand extreme events and to reduce the probability that we will be surprised. We first develop a theoretical framework to describe these complex interactions that builds on ideas from a number of disciplines, in particular, ecology and atmospheric sciences; then, we present several key examples from different systems to illustrate emerging patterns and concepts, as well as insights to improving management.}, author = {Debra C. Peters} } @article {50702, title = {Strategies for ecological extrapolation}, journal = {Oikos}, volume = {106}, number = {3}, year = {2004}, month = {September 1, 200}, pages = {627-636}, abstract = {

Extrapolation of information collected at fine scales to broader scales is an increasingly important issue in ecology as the recognition of spatial connections within and among different levels of organization expands. In addition, our ability to represent complex behavior in ecological systems has improved with readily available instrumentation and software that allows detailed sampling and analysis and the ease with which geospatial data can be used to support large spatial simulation models or extensive data-based inventories and assessments. However, there is a tradeoff between simple approaches having errors associated with excluding processes and more complex approaches that are plagued by high uncertainty due to increased estimation and measurement error. In this paper, we develop a synthetic, problem-solving framework for extrapolating information from fine to broad scales that is applicable to a wide range of ecological problems. The framework includes three classes of approaches that differ in their complexity and sources of error: nonspatial, spatially implicit, and spatially explicit. We consider a range of ecological issues requiring complex approaches (i.e., nonlinear processes, thresholds, positive feedbacks, neighborhood processes) and identify options for dealing with these issues. Our operational framework of model selection serves as a practical and objective approach to the problem of ecological prediction across a range of spatial and temporal scales. Thus, this framework should be of interest to all ecologists concerned with the problem of prediction.

}, keywords = {complex, complex behaviors, define and control prediction, ecological extrapolation, exclude key processes, increased estimation, ingenerating accurate, measurable reduction, measure, measurement error, models, prediction bias, prediction errors, propagation, software, spatial extrapolation ofinformation are an important issue in ecology. Althoughimprovements in instrumentation, trade-offsimpedes, unknown prediction}, doi = {10.1111/j.0030-1299.2004.12869.x}, url = {/files/bibliography/04-003.pdf}, author = {Debra C. Peters and D.L. Urban and Gardner, R.H. and David D. Breshears and Jeffrey E. Herrick} } @conference {50704, title = {Vegetation-water budget interactions: Implications for ecosystem dynamics at multiple scales}, booktitle = {89th Annual Meeting, Ecological Society of America}, year = {2004}, month = {August 1, 2004}, pages = {p. 397}, address = {Portland, OR}, abstract = {Landscape-scale water budgets are often assumed to be driven by broad-scale gradients in topo-edaphic factors that influence run-on, runoff, and local plant available water. Feedbacks between vegetation and hydrologic processes are typically ignored. However, in arid landscapes interactions between vegetation type, soil properties, and hydrologic processes can significantly affect plant available water with effects on production at multiple scales. Our goal was to develop a framework for predicting ecologically meaningful water budgets and plant biomass for heterogeneous landscapes using information from processes operating at finer spatial scales (plant, patch). We examined the role of fine-scale vegetation-soil process interactions and topo-edaphic factors in generating patch and landscape-scale hydrology with feedbacks to vegetation. We assessed the importance of these processes on the dynamics of {\textquoteright}beads{\textquoteright}---small patches of vegetation (< 100 m2) and microtopography interspersed across Chihuahuan Desert bajada landscapes. Fine-scale processes associated with plant canopies versus bare soil areas significantly affect run-on/runoff patterns and the {\textquoteright}fate{\textquoteright} of soil water (i.e., whether water is used for plant transpiration and production or lost to evaporation). Increasing plant cover is associated with increased {\textquoteright}trapping{\textquoteright} of soil water with effects on the ratio of evaporation to transpiration. We used a spatially interactive simulation model to integrate fine-scale processes to broader scales and to predict the consequences for vegetation cover of beads and associated landscapes. The consequences of {\textquoteright}missing{\textquoteright} the presence and function of beads and other fine-scale water catchment areas in developing landscape-scale water budgets is discussed.}, author = {Debra C. Peters and K. A. Snyder and John Wainwright and A.J. Parsons} } @conference {50804, title = {Understanding vegetation dynamics provides insights to sustainable invasive plant management and remediation strategies}, booktitle = {7th International Conference on the Ecology and Management of Alien Plant Invasions (ESA/WSSA Joint Meeting)}, year = {2003}, month = {November 3-7, 20}, pages = {68}, address = {Fort Lauderdale, FL}, abstract = {Our objective is to provide insights into the management of invasive species and remediation of native ecosystems using a combination of long-term studies of vegetation dynamics, short-term process-based experiments, and integrative simulation models. Throughout the western US, encroachment by native woody species into perennial grasslands has been occurring over the past 100 to 200 years. Permanent plots located at long-term research stations have documented this invasion process since the early 1900{\textquoteright}s. Recent analyses of these long-term data show high spatial variability in shrub invasion rates and grass persistence at the landscape scale. This high spatial variability in grass/shrub interactions and dynamics led to short-term experiments to identify the key processes influencing grass persistence on some sites and inability of grasses to recover on others. A simulation model that integrates key biotic processes and abiotic drivers was used to predict the sites most sensitive or responsive to remediation efforts and those sites most resistant to change. Thus, remediation strategies based on an integration of long-term observations, results from short-term experiments, and simulation model analyses have a greater probability of success than a single approach. These tools are also useful in improving our understanding and management of invasive species.}, author = {Debra C. Peters and Kris Havstad and Jin Yao} } @conference {50923, title = {Introduction and overview: approaches to addressing landscape-scale problems in ecology}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {41}, address = {Tucson, AZ}, abstract = {This talk provides an introduction to the symposium that will address tradeoffs and consequences of using alternative scaling approaches to deal with timely and critical ecological issues. Wildlife conservation, patterns and dynamics in carbon sequestration, loss of biodiversity, spread of invasive species, and atmosphere-biosphere interactions are issues that require an explicit consideration of spatial and temporal scaling at the landscape level. We present three major approaches to addressing these types of ecological problems that vary in their complexity and degree of spatial interactions. Each approach is discussed in terms of its strengths and weaknesses. Examples of the types of questions most suited to each approach are given. Each core talk covering the major scaling approaches is co-authored by a team of experts representing each of the following disciplines: vegetation dynamics, wildlife conservation, and carbon and soil water dynamics. We also present several highly visible and important case studies to illustrate the connections and relatedness among approaches and disciplines. We demonstrate the relevance of these approaches to addressing landscape-scale problems both by scaling information up from plots and by scaling down from coarse regional data. Although it is widely recognized that scaling is an important issue, there have been few attempts to provide guidance in selection and use of different approaches. This symposium provides this synthetic overview.}, author = {Debra C. Peters and D.L. Urban and Jeffrey E. Herrick} } @conference {50927, title = {Introduction: Approaches to scaling information from plots or regions to landscapes}, booktitle = {US-International Association for Landscape Ecology}, year = {2002}, month = {April 23-26, 200}, pages = {81}, address = {Lincoln, NE}, abstract = {This talk provides an introduction to the symposium that will address the tradeoffs and consequences of using alternative scaling approaches to dealing with critical and timely ecological issues. Three major approaches will be described that vary in their complexity and degree of spatial interactions: (1) nonspatial, (2) spatially implicit, and (3) spatially interactive. Each approach will be introduced in terms of its strengths and weaknesses. Examples of the types of questions most suited to each approach will also be given. Each talk will be co-authored by representatives of the following disciplines: vegetation dynamics, wildlife conservation, or carbon and soil water dynamics. Case studies will be used to illustrate the connections and relatedness among approaches and disciplines. The relevance of these approaches to addressing landscape-scale problems will be addressed both by scaling information up from plots and by scaling down from coarse regional data. Although it is widely recognized that scaling is an important issue, there have been few synthetic attempts to provide guidance in selection and use of different types of approaches. This synthetic overview will be provided as part of our symposium.}, author = {Debra C. Peters and Durban, D.L.} } @conference {50924, title = {Landscape-scale consequences of patch-scale invasion success or failure}, booktitle = {US-International Association for Landscape Ecology}, year = {2002}, month = {April 23-26, 200}, pages = {109}, address = {Lincoln, NE}, abstract = {Shrub invasion into perennial grasslands has occurred throughout many arid ecosystems in the US and abroad. Although various factors contributing to invasion have been well studied, there is little understanding of the spatial variation in shrub success into different plant communities. The objective of this study was to examine differential invasion success by the shrub, creosotebush, into grasslands dominated by different species. The study was conducted at the Sevilleta LTER site in central New Mexico, USA, where the landscape consists of a mosaic of patches and ecotones between several grass and shrub species. Sampling was conducted by geo-referencing the location of all shrub plants within patches dominated either by blue grama, a dominant species in the shortgrass steppe, or by black grama, a dominant of the Chihuahuan Desert. Vegetation was sampled within and outside of each shrub patch. Results show that creosotebush-black grama ecotones are diffuse, consisting of a complex mosaic of grasses and shrubs. By contrast, ecotones between creosotebush and blue grama are distinct with very few shrub plants found within patches dominated by blue grama. Consequences of these patch-scale interactions for landscape-scale patterns in shrub invasion and grass resistance are discussed.}, author = {Debra C. Peters} } @article {50926, title = {Plant species dominance at a grassland-shrubland ecotone: An individual-based gap dynamics model of herbaceous and woody species}, journal = {Ecological Modelling}, volume = {152}, number = {1}, year = {2002}, month = {June 1, 2002}, pages = {5-32}, abstract = {

Transition zones or ecotones between biomes are predicted to be particularly sensitive areas to directional changes in climate. However, for many ecotones, there is little understanding of the key processes that allow dominant species from adjacent biomes to coexist at transition zones and how differences in these processes affect species responses to changes in environmental conditions. The objective of this study was to examine the relationship between plant life history traits and patterns in dominance and composition at a grassland{\textendash}shrubland transition zone in order to predict shifts in dominance with directional changes in climate. It was hypothesized that differences in life history traits allow species from adjacent biomes to coexist at this transition zone, and that these dominance patterns are dynamic through time as a result of species-specific responses to changes in climate. A mixed lifeform individual plant-based gap dynamics model (ECOTONE) was developed to examine consequences of differences in recruitment, resource acquisition, and mortality to patterns in species dominance and composition under a variety of soils and climatic conditions. This model is unique because it represents interactions among multiple potential dominant species that include congeneric species of one lifeform as well as herbaceous and woody lifeforms across multiple spatial scales. Similar to other gap models, ECOTONE simulates the recruitment, growth, and mortality of individual plants on a small plot through time at an annual timestep. ECOTONE differs from other gap models in the degree of detail involved in determining successful recruitment by each species and in the simulation of belowground resources. Individual plant root distributions and resource availability by depth are dynamic. Soil water content is simulated on a daily timestep and nitrogen is simulated monthly. Multiple spatial scales can be simulated using a grid of plots connected by seed dispersal. ECOTONE was parameterized for two soil types at the Sevilleta National Wildlife Refuge (SEV), a site located within the transition zone between two major biomes in North America. Shortgrass steppe communities are dominated by the perennial grass Bouteloua gracilis (blue grama) and Chihuahuan desert communities are dominated by the perennial grass Bouteloua eriopoda (black grama) or the shrub Larrea tridentata (creosotebush). Experiments were conducted to provide key parameters related to recruitment and growth that were supplemented with information from the literature for remaining parameters. Model output was verified using field estimates of cover and biomass for the three dominant species as well as other groups of species. Simulation analyses were conducted under current climate and for a directional change in climate. Nitrogen was assumed constant for all runs to allow a focus on water availability constraints as affected by climate. Under current climatic conditions, simulated biomass on sandy loam soils was dominated by B. eriopoda with smaller biomass of B. gracilis and other species groups. By contrast, simulated biomass on a loamy sand soil was codominated by B. eriopoda and L. tridentata with very small biomass attributed to other species groups. Under a GFDL climate change scenario of increased year-round temperatures and increased summer precipitation, vegetation patterns shifted to a clear dominance of biomass by B. eriopoda on both soil types. These results show that temporal partitioning of soil water is important to codominance by the two Bouteloua species, and that spatial and temporal partitioning of soil water is important for grass{\textendash}shrub interactions. The results also suggest that global climate change may provide a mechanism for the recovery of B. eriopoda following shrub invasion in the Southwestern U.S. Thus, an individual-based modeling approach is capable of representing complex interactions among herbaceous and woody species as well as between congeneric species with different life history traits at a biome transition zone. This modeling approach is useful in improving our understanding of key processes driving these vegetation dynamics as well in predicting shifts in dominance as environmental conditions change in the future.

}, keywords = {Bouteloua species, Chihuahuan Desert, climate change, creosotebush, ECOTONE, shortgrass steppe}, doi = {10.1016/S0304-3800(01)00460-4}, url = {files/bibliography/JRN00362.pdf}, author = {Debra C. Peters} } @article {50925, title = {Recruitment potential of two perennial grasses with different growth forms at a semiarid-arid transition zone}, journal = {American Journal of Botany}, volume = {89}, number = {10}, year = {2002}, month = {October 1, 2002}, pages = {1616-1623}, abstract = {

The objective of this study was to quantify differences in recruitment potential (seed production, seed presence in the soil) for two congeneric perennial grasses (Bouteloua gracilis, Bouteloua eriopoda [Poaceae]) that dominate adjacent arid and semiarid grassland biomes. It was hypothesized that these species have different recruitment strategies at the biome transition zone that are related to differences in their growth form and longevity. Recruitment potential for each Bouteloua species was compared in patches dominated by one or both species or codominated by the invasive shrub, Larrea tridentata (Zygophyllaceae). Regional variation in recruitment was examined for B. gracilis for cases in which comparable data were available in the literature for a site located within the semiarid grassland biome. The short-lived stoloniferous species B. eriopoda produced more seeds per plant than the long-lived bunchgrass B. gracilis, yet seed viability (\<60\%) and presence in the soil were lower. Mean viability of B. gracilis was higher (\>90\%) than that of B. eriopoda, and a greater percentage of seeds produced on a square meter basis was found in the soil (10{\textendash}25\%). Similar patterns were found for both species in all grass-dominated patches. Bouteloua eriopoda plants growing in patches codominated by L. tridentata produced fewer seeds per plant with lower viability, and fewer seeds were found in the soil compared to grass-dominated patches. Regional comparisons found greater seed production per square meter and more seeds in the soil for B. gracilis at the transitional site compared with a cooler, wetter site located within the semiarid grassland biome. These differences in recruitment potential along with published differences in rates of seedling establishment and vegetative spread may explain, at least in part, localized patterns in species dominance.

}, keywords = {Bouteloua eriopoda, Bouteloua gracilis, Chihuahuan Desert grasslands, grass{\textendash}shrub interactions, intra- and interspecific interactions, Poaceae, seed production, shortgrass steppe}, doi = {10.3732/ajb.89.10.1616}, url = {files/bibliography/JRN00364.pdf}, author = {Debra C. Peters} } @conference {51030, title = {Climatic triggers for nonlinear and threshold responses of rangelands}, booktitle = {86th Annual Meeting, Ecological Society of America}, year = {2001}, month = {August 6-10, 200}, pages = {31}, address = {Madison, WI}, abstract = {Climatic triggers to threshold responses have been observed for a number of ecosystem types, although our understanding and prediction of these responses remain limited. Our objective was to examine and synthesize the conditions under which climate is expected to trigger both larger and smaller than expected positive or negative ecosystem responses. These ecosystem "surprises" are related to interactions among properties of the climate (severity, duration, and frequency of extreme events), vegetation (e.g., species composition, age structure, and sex ratios) and soil (e.g., water-holding capacity, soil organic matter content). Management has important influences on the vegetation and soil that affect the ability of the ecosystem to respond to climatic events. Furthermore, thresholds observed at one spatial or temporal scale may or may not be observed at larger or smaller scales. We illustrate the importance of these interacting properties to ecosystem responses to climate across temporal and spatial scales using both paleoecological data and information from current vegetation for a number of ecosystem types. We then provide a general framework for understanding climatic triggers to threshold responses that can be used to guide research and assist in setting management priorities.}, author = {Debra C. Peters and Betancourt, J.L.} } @conference {51029, title = {Landscape consequences of small-scale disturbances at a grassland-shrubland ecotone}, booktitle = {16th Annual Symposium, US-International Association of Landscape Ecology}, year = {2001}, month = {April 25-29, 200}, pages = {200}, address = {Tempe, AZ}, abstract = {The objective of this study was to evaluate the role of small-scale disturbances within different patch types to landscape-scale patterns in species composition and dominance at a shortgrass steppe-Chihuahuan Desert ecotone. Species removals were conducted at the Sevilleta LTER in central New Mexico within five different patch types where communities are dominated or codominated by one of two perennial grasses (blue grama, black grama) and one shrub (creosotebush). Within each patch type, all plants of the dominant species were removed from five 3m x 4m plots starting in 1995; five control plots were also located within each patch type. Cover and density by species have been estimated annually. Similarity indices were used to compare patch-scale patterns in species composition with the landscape mosaic. Annuals dominated all removal plots one year after removals were initiated. Subsequent recovery patterns depended upon the dominant species removed. Blue grama removal resulted in establishment and growth of perennial grasses, whereas removal of black grama promoted recovery by perennial forbs. Removal of creosotebush in mixed communities with black grama resulted in recovery by perennial forbs, grasses, and shrubs whereas removal of this species in shrub-dominated communities resulted in little change in the vegetation. These results indicate that mortality of dominant species by small-scale disturbances has dramatic effects on vegetation patterns that may alter the landscape mosaic at this arid-semiarid ecotone.}, author = {Debra C. Peters} } @article {51028, title = {Modelling vegetation change and land degradation in semiarid and arid ecosystems: an integrated hierarchical approach}, journal = {Advances in Environmental Monitoring and Modeling}, volume = {1}, number = {2}, year = {2001}, month = {May 1, 2001}, pages = {1-29}, abstract = {Despite the dedication of significant human, financial and technological resources, dryland degradation continues unabated in both the developed and developing world. Many of the causes have been described and the consequences extensively documented. Here, we argue that the failure of attempts to stop or reverse dryland degradation can be explained by a failure to 1) recognize when ecosystems have crossed ecological, edaphic o geomorphic thresholds, and 2) identify and address the properties and/or processes at relevant scales that confer resistance and resilience. We illustrate how simulation models can be used to address these limitations using examples from one type of model, an individual-based gap dynamics model of grasslands and shrublands (ECOTONE). We used ECOTONE to predict the effects of climatic fluctuations and disturbance frequency on local and regional patterns in species dominance and composition. Results show that patterns in dominance between 2 perennial grasses (Bouteloua gracilis, Bouteloua eriopoda) at the biome transition zone are not predictable based on responses within each biome. An increase in disturbance frequency at the ecotone shifted plant communities to dominance by the short-lived B. eriopoda from communities codominated by B. gracilis or the shrub Larrea tridentata. We propose a strategy that addresses problems in semiarid and arid ecosystems more effectively than previous approaches based on an integrated, hierarchical modeling approach. This approach employs multiple tools, such as geographic information systems, state and transition models, remote sensing, and expert knowledge, in an iterative approach with simulation models. This strategy is applicable to research on processes of dryland degradation and management projects to stop or reverse degradation.}, url = {/files/bibliography/01-043.pdf}, author = {Debra C. Peters and Jeffrey E. Herrick} } @article {51103, title = {Climatic variation and simulated patterns in seedling establishment of two dominant grasses at a semi-arid and grassland ecotone}, journal = {Journal of Vegetation Science}, volume = {11}, number = {4}, year = {2000}, month = {August 1, 2000}, pages = {493-504}, abstract = {Seedling establishment by two congeneric C4 perennial grasses (Bouteloua gracilis and B. eriopoda) that dominate semiarid and arid North American grasslands was simulated by modeling multiple temporal frequencies of climate at their ecotonal boundary. The occurrence of a recruitment event in each year was determined by comparing simulated soil water content through time with amount and timing of soil water required for establishment based on data in the literature for each species. The two Bouteloua species had different regeneration strategies. B. gracilis had a broad pattern of establishment that occurred from June through October with a peak in September and October when year-to-year variation in precipitation was high. B. eriopoda had a narrow distribution of establishment events that peaked in the middle of summer (July) when precipitation amounts were most reliable. Interdecadal variation in climate had species-specific effects on establishment. Climatic condition from 1949 through 1968 were more favorable for B. eriopoda establishment compared to the cooler, wetter conditions from 1969 through 1988 that favored B. gracilis. Establishment of B. eriopoda was negatively affected by El Nino events, whereas B. gracilis establishment was positively affected by conditions associated with El Nino events. A long-term directional increase in annual precipitation resulted in a small shift in the geographic location of the ecotonal boundary based upon the location of similar establishment probabilities for the two species. These results indicate that temporal partitioning of soil water required by seedlings may account for species coexistence at an ecotonal boundary.}, keywords = {B. eriopoda, Bouteloua gracilis, ECOTONE, seedling establishment}, url = {/files/bibliography/00-016.pdf}, author = {Debra C. Peters} } @conference {51106, title = {Controls on patterns in species dominance across multiple spatial scales at a biome transition zone}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {372}, address = {Snowbird, UT}, abstract = {Grassland landscapes at the SEV-LTER consist of a mosaic of patches of variable size and shape that are dominated or codominated by one of two Bouteloua species that characterize two other LTER sites. Bouteloua gracilis (blue grama) dominates shortgrass steppe ecosystems at the SGS-LTER in northern Colorado, and B. eriopoda (black grama) dominates Chihuahuan Desert grasslands at the JER-LTER in southern New Mexico. Our overall objective of this ongoing work is to examine controls on patterns in dominance by these species at the shortgrass steppe/Chihuahuan Desert biome transition zone in central New Mexico. A combination of field investigations, experiments, and simulation model analyses are being used to evaluate the key abiotic variables and biotic processes controlling these patterns. Broad-scale patterns in dominance are related to interactions between climate, topography, and soils. As the spatial scale decreases, the importance of patchily distributed disturbances to species dominance increases. Recruitment strategies and temporal partitioning of soil water are key processes determining dominance patterns under different environmental conditions. Predictions from simulation model analyses indicate that a trend toward hotter growing seasons or an increased frequency of disturbance will result in shifts in dominance to black grama, the Chihuahuan Desert species.}, keywords = {biome transition zone, grassland, patterns, SEV-LTER, spatial scales, species dominance}, author = {Debra C. Peters and J. R. Gosz} } @conference {51105, title = {Cross-site comparisons of climate and vegetation for two semiarid grasslands and their ECOTONE}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {372}, address = {Snowbird, UT}, abstract = {The objective of this ongoing work is to compare ecosystem characteristics of three LTER grassland sites located along a north-south aridity gradient. These sites share some characteristics and differ in others that are expected to be important to their ability to respond to environmental drivers, including climate change and land use. The SGS-LTER in northern Colorado is representative of the shortgrass steppe and is dominated by th long-lived bunchgrass, Bouteloua gracilis (blue grama). Grasslands at the JER-LTER in southern New Mexico are dominated by the short-lived stoloniferous grass, Bouteloua eriopoda (black grama). Landscapes at the SEV-LTER in central New Mexico consist of patches that are dominated or codominated by these two species. Regional analyses of the climate and simulated recruitment showed important differences between biomes that may account, at least in part, for observed patterns in dominance and species diversity. Field studies of seed production and seed storage in the soil, as well as simulation analyses, showed the responses of these species at their ecotone are not predictable based on responses within the biomes where they dominate.}, keywords = {characteristics, ecosystem, grassland, LTER}, author = {Debra C. Peters} } @inbook {51104, title = {Landscape Diversity}, booktitle = {Encyclopedia of Biodiversity}, volume = {3}, year = {2000}, month = {October 25, 2000}, pages = {648-658}, publisher = {Academic Press}, organization = {Academic Press}, address = {Princeton, NJ}, abstract = {While biodiversity is usually considered at the species level, maintenance of biodiversity requires management at higher levels of organization, particularly at the landscape scale. It is difficult to manage for each threatened species individually. Alternatively, management can focus on the ecosystems that contain these species, and on the landscapes where ecosystems are found. The relatively new discipline of landscape ecology provides insight into both landscape diversity and species diversity, and suggests a theoretical and practical basis for conservation planning. There are three basic characteristics of landscapes that affect their diversity: structure, function and dynamics. Structure is the most well-understood element of landscapes. It is also the most obvious- nearly any aerial view will show a mixture of different landforms, habitats, or vegetation types. The patch is the basic unit of landscape structure. The characteristics of patches and the spatial relationships among patches are important components of landscapes. The distributions of energy, materials, and species among patches differing in size, shape, abundance, and configuration are particularly important to patterns in diversity at the landscape scale. The other two elements of landscapes go beyond a description of spatial heterogeneity. Function is concerned with interactions among the spatial elements of a landscape, including flows of energy, materials, and species among patches. Landscape dynamics includes characteristics of both structure and function in order to examine changes in pattern and process over time. Conservation and management of biodiversity requires understanding of all three of these elements, including the effects of human activities on the system.}, keywords = {biodiversity, dynamics, function, landscape ecology, maintenance, management, structure}, url = {/files/bibliography/00-020.pdf}, author = {Debra C. Peters and Sarah Goslee}, editor = {Simon Asher (ed. Levin} } @conference {51101, title = {Plant species dominance and disturbance at a grassland-shrubland ecotone}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {175}, address = {Snowbird, UT}, abstract = {The objective of this study was to evaluate the role of presence and identity of dominant species on vegetation patterns at a shortgrass steppe- Chihuahuan desert ecotone. Species removals were conducted: (1) to identify new dominant species and assemblages after the current dominant is removed, and (2) to determine if dominant species with different life history traits shave different legacy effects on recovery of other species through time. This study was conducted at the Sevilleta LTER in central New Mexico where communities may be dominated or codominated by one of two perennial grasses (blue grama, black grama) and one shrub (creosotebush). Within each community, all plants of the dominant species were removed from within 5 3m x 4m plots in 1995, and have been removed annually since that time. Five control plots were also located at each site. Cover and density by species have been estimated annually since 1995. Annuals dominated all removal plots one year after removals were initiated. Subsequent recovery patterns depended upon the dominant species removed. Blue grama removal resulted in establishment and growth of perennial forbs whereas removal of black grama promoted recovery by perennial grasses. Removal of creosotebush in mixed communities with black grama resulted in recovery by perennial forbs, grasses, and shrubs whereas removal of this species in shrub-dominated communities resulted in little change in the vegetation. Legacy effects were most important in the first few years after removals were initiated. These results indicate that removal of dominant species by disturbances have dramatic effects on vegetation patterns that may alter the landscape mosaic at this arid-semiarid ecotone.}, keywords = {disturbance, ECOTONE, grassland, plant species dominance, Sevilleta LTER, shrubland}, author = {Debra C. Peters} } @conference {51102, title = {Plant-soil feedbacks and recruitment constraints on perennial grass recovery following shrub invasion}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {372}, address = {Snowbird, UT}, abstract = {Recent climate change simulation analyses predict an expansion of Chihuahuan Desert grasslands and reduction in shrublands in the southwestern U.S. Our objective is to evaluate the importance of plant life history traits and soil development processes to responses of these ecosystems. We are using a spatially interactive gap dynamics model (ECOTONE) to predict vegetation responses for a variety of initial soil conditions, from well-structured soils with relatively high soil organic matter to highly degraded soils. Our model includes feedbacks between soil organic matter, water availability, plant recruitment, and growth. We are simulating sites located throughout the Chihuahuan Desert including the SEV-LTER and JER-LTER. We are also examining the importance of seed dispersal to the recovery of perennial grasses. Our results show that recovery at the landscape scale is highly heterogeneous and depends both on nthe initial vegetation and soil properties, as well as the modification of these properties through time due to plant-soil feedbacks. Recruitment is more important than plant growth in determining grass response. Recovery is also affected by climate interacting with vegetation and soil properties. Our plans include expanding the spatial component of the model to include the redistribution of water, soil, and nutrients across the landscape.}, keywords = {ECOTONE, perennial grass, predict, recovery, seed dispersal, shrub invasion}, author = {Debra C. Peters and Jeffrey E. Herrick} } @conference {51178, title = {Landscape-scale processes and sensitivity of Chihuahuan Desert ecosystems to climate change}, booktitle = {5th World Congress, International Association for Landscape Ecology}, volume = {II (L-Z)}, year = {1999}, month = {July 29-August 3}, pages = {122}, address = {Snowmass Village, CO}, abstract = {

Our objective was to predict the response of Chihuahuan desert landscapes to climate change using a multiscale approach that includes vegetation-soil feedbacks, seed source and seed dispersal across the landscape. We used vegetation, soils, and climate maps for the Sevilleta National Wildlife Refuge LTER site (SNWR) in central New Mexico as input parameters in a spatially explicit, individual, plant-based simulation model (ECOTONE). The model incorporates feedbacks among vegetation and soil properties and processes that are important to perennial grass establishment and survival. We used the model to predict the locations most likely to shift from shrub- to grass-dominated vegetation due to changes in climate. Our results showed an increase in perennial grass cover throughout the SNWR. Sensitivity of shrub-dominated locations was dependent upon soil texture and distance to the nearest perennial grass seed source. Feedbacks between changes in species composition and soil organic matter modified the rate of change in dominant species. Our results demonstrate the importance of landscape-scale processes and vegetation-soil feedbacks to shifts in vegetation at ecotones.

}, author = {Debra C. Peters and Jeffrey E. Herrick} } @conference {51177, title = {Vegetation-soil feedbacks and sensitivity of Chihuahuan Desert ecosystem boundaries to climate change}, booktitle = {84th Annual Meeting, Ecological Society of America}, volume = {80}, year = {1999}, month = {August 8-12, 199}, pages = {69}, address = {Spokane, WA}, abstract = {

Geographic distributions of species and ecosystems are predicted to shift with regional and global changes in climate. Our objective was to predict changes in the regional distribution of Chihuahuan desert grasslands using a landscape-scale approach that incorporates vegetation-soil feedbacks. We used a spatially-explicit individual plant-based model to simulate vegetation responses at locations differing in species composition, soils, and climate. The model incorporates feedbacks among vegetation and soil properties and processes that are important to perennial grass establishment and survival. We used the model to predict the landscape and regional locations most likely to shift from shrub- to grass-dominated vegetation in response to changes in climate. Because climate and texture vary at different scales, our results generated a complex mosaic of sensitivity of these ecosystems to climate change. Soil texture was more important than initial soil organic matter content in the shift from shrub to grasses. Feedbacks between soil organic matter and changes in species composition increased the rate of this change. Our results demonstrate the importance of including landscape-scale variability in vegetation and soil processes in predicting ecosystem boundary shifts in response to global climate change.

}, author = {Debra C. Peters and Jeffrey E. Herrick} }