@article {JRN55414, title = {Cross-Site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network}, journal = {BioScience}, volume = {72}, year = {2022}, month = {8/16/2022}, pages = {889-907}, abstract = {Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.}, keywords = {ANPP, climate change, disturbance, drought, LTER, wildfire}, doi = {https://doi.org/10.1093/biosci/biab134}, url = {files/bibliography/22-023.pdf}, author = {Amy R Hudson and Debra P C Peters and John M Blair and Daniel L. Childers and Peter T Doran and Kerrie Geil and Micheal Gooseff and Katherine L Gross and Nick Haddad and Melissa A Pastore and Jennifer A Rudgers and Osvaldo Sala and Eric W Seabloom and Gaius Shaver} } @article {JRN55199, title = {Long-term ecological research and evolving frameworks of disturbance ecology}, journal = {BioScience}, volume = {70}, year = {2020}, month = {02/2020}, pages = {141-156}, chapter = {141}, abstract = {Detecting and understanding disturbance is a challenge in ecology that has grown more critical with global environmental change and the emergence of research on social{\textendash}ecological systems. We identify three areas of research need: developing a flexible framework that\  incorporates feedback loops between social and ecological systems, anticipating whether a disturbance will change vulnerability to other environmental drivers,\ and incorporating changes in system sensitivity to disturbance in the face of global changes in environmental drivers. In the present article, we\ review how discoveries from the US Long Term Ecological Research (LTER) Network have influenced theoretical paradigms in disturbance\ ecology, and we refine a framework for describing social{\textendash}ecological disturbance that addresses these three challenges. By operationalizing this\ framework for seven LTER sites spanning distinct biomes, we show how disturbance can maintain or alter ecosystem state, drive spatial patterns\ at landscape scales, influence social{\textendash}ecological interactions, and cause divergent outcomes depending on other environmental changes. }, keywords = {disturbance, ecological research networks, ecological theory, LTER, social{\textendash}ecological studies}, doi = {10.1093/biosci/biz162}, url = {files/bibliography/20-009.pdf}, author = {Gaiser, Evelyn E. and Bell, David M. and Max Castoroni and Daniel L. Childers and Peter M. Groffman and Rhett G. Jackson and Kominoski, John S. and Debra C. Peters and Steward T.A. Pickett and Ripplinger, Julie and Zinnert, Julie C.} } @inbook {JRN52666, title = {Cross-site comparisons of precipitation and surface water chemistry}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {46-50}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {6}, address = {Springfield, Virginia}, abstract = {

Measurements of pools and fluxes of transport or cycling of elements and compounds through the biotic and abiotic components provide critical information about the function of ecosystems. Because the time for a molecule to be completely transported through an ecosystem may be decades to millennia, long-term data provide one of the few means to estimate how ecosystems use and respond to changes in inputs of nutrients and toxic substances. This chapter tests two hypotheses related to patterns in biogeochemistry across sites: (1) patterns in atmospheric deposition over the past 20 years are different for the eastern and western parts of the U.S., and (2) changes in atmospheric deposition are related to changes in human population density for some sites. Long-term data, collected at multiple sites across the US, in chemical measurements in wet deposition, e.g., sulfur dioxide, nitrogen oxide, and ammonia emission data, and in human population size support both hypotheses.\  The results illustrate that the effects of human activities on biogeochemistry vary regionally and across the continent, and demonstrate that cross-site comparisons of long-term data can provide new insights into the spatial patterns of transport and cycling of elements and compounds.

}, 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/13-029-6.pdf}, author = {Charles T. Driscoll and Peter M. Groffman and John M Blair and Ariel E. Lugo and C. Laney and Debra C. Peters} } @inbook {JRN52673, title = {Management and policy implications of cross-and within-site, long-term studies}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {206-215}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {15}, address = {Springfield, Virginia}, abstract = {

This chapter explains the implications long-term data bring to natural resource management and policy-making.\  It first explains the two perspectives of long-term data, then explains the values brought by the two perspectives to natural resource management.\  The two perspectives are retrospective and predictive:\  long-term data enable us to examine data retrospectively to identify temporal and spatial sensitivities, and to build these historical perspectives into predictive models where we can objectively evaluate potential future scenarios. The values are as follows.\  First, with the understandings gained by retrospectively examining the long-term data, the managers can develop data-based guidelines to direct the appropriate timing and application of management practices.\  Second, long term data provide the opportunity to evaluate policies and programs that have been implemented for resource conservation.\  The ability to evaluate environmental responses following policy implementation provides the data necessary to validate policies or may lead to their subsequent revision.\  Third, long term data collection provides the opportunity for clients, partners, and stakeholders to be engaged in scientific processes. These interactions create opportunities, not only for technology and information transfers, but for users to inform the science and its research directions.\  Fourth, the predictive models built based on long-term data can be used to estimate the effects of a variety of climatic and management scenarios and are critical to informed decision-making and effective communication between natural resource managers and policy makers.

}, 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/13-029-15.pdf}, author = {Kris Havstad and Joel R. Brown} } @inbook {JRN52665, title = {Patterns of net primary production across sites}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {42-45}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {5}, address = {Springfield, Virginia}, abstract = {

Net primary production (NPP) is a fundamentally important and commonly measured ecosystem process that provides an integrative estimate of energy capture and flow into systems, and consequently the energy available for use by other trophic levels. A wide range of productivity levels occurs globally with high temporal dynamics among sites. This chapter discusses approaches to estimating NPP, highlights site-specific trends in productivity, and provides examples of past synthetic analyses across space and time. In terrestrial ecosystems, aboveground NPP are commonly measured or estimated. In many sites, spatial variation in NPP among locations within a site can overwhelm temporal variation.\  In terms temporal patterns, at some sites clear temporal trends exist: NPP either increases or decreases with time; at other sites, strong interannual variations exist.\  Past synthetic analyses have provided key insights into the relative roles of biotic versus abiotic drivers of dynamics as well as elucidating where and when biogeochemical versus climatic factors underlie patterns of NPP across biomes.\  The chapter proposes four questions that can be addressed as long-term data sets at more sites become available.

}, 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/13-029-5.pdf}, author = {A. K. Knapp and M. D. Smith and Debra C. Peters and S.L. Collins} } @inbook {JRN52663, title = {History and organization of the EcoTrends project}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {21-27}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {2}, address = {Springfield, Virginia}, abstract = {

This chapter describes the internal organization and timeline of the EcoTrends Project, from which the data and recommendations in the subsequent chapters are generated.\  The project began in 2004, and its organizational structure expanded over the next six years to include many activities and dozens of individuals from six major groups.\  The six major groups are the EcoTrends Project Office, the EcoTrends Editorial Committee, the EcoTrends Technical Committee, participating site scientists, information managers, and technical staff, the Long Term Ecological Research Network Office, and the EcoTrends Socioeconomic Working Group.\  The major activities occurred from 2004 to 2010, when this book is completed, are listed in the chapter.

}, 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/13-029-2.pdf}, author = {C. Laney and Debra C. Peters and Baker, K. S.} } @inbook {JRN52674, title = {Recommendations for data accessibility}, year = {2013}, pages = {216-225}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {16}, address = {Springfield, Virginia}, abstract = {

The EcoTrends project has generated hundreds of standardized, documented datasets from many sites and scientific fields.\  During the process of generating data comparable between many sites and across several organizational networks, novel solutions to technical, organizational, and communication challenges have been created.\  This chapter presents ten recommendations for site-level information management and for future synthesis projects.\  The recommendations are related to three broad categories: (1) data management and products, (2) project design, and (3) information environments to support synthesis projects. For each recommendation, the chapter provides specific examples of the challenges that EcoTrends faced, the lessons learned, and then explains the recommendation that may help address the challenge in future projects.

}, 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/13-029-16.pdf}, author = {C. Laney and Baker, K. S. and Debra C. Peters and Ken Ramsey} } @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 {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 {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} } @inbook {JRN52668, title = {Cross-site studies "by design:" Experiments and observations that provide new insights}, booktitle = {Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change}, year = {2013}, pages = {72-80}, publisher = {National Technical Information Services}, organization = {National Technical Information Services}, chapter = {10}, address = {Springfield, Virginia}, abstract = {

The cross-site comparisons presented in the previous chapters are all conducted after the individual studies are completed.\  The differences in experimental design in individual studies in a posteriori cross-site studies limit the scope of questions that can be addressed, and the powerfulness and confidence in the conclusions.\  This chapter describes cross-site studies that are {\textquotedblleft}by design{\textquotedblright} where the questions, experimental layout, methods, and measurements included multiple sites from the beginning. These a priori cross-site studies provide powerful tools to understand the phenomenon of global change and to predict its impacts on ecosystems and society. Two types of a priori cross-site studies are described: (1) experimental manipulations of drivers or system properties, and (2) observations or monitoring of natural or managed ecosystems located along environmental gradients. Within each type, examples of both on-going or completed experiments and new or developing experiments are presented.\  For each example, insights that would not have been obtained with other approaches are also presented. The limitations and difficulties of this type of studies are listed.

}, 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/13-029-10.pdf}, author = {Jin Yao and O. E. Sala and Debra C. Peters} } @article {49944, title = {The ecology of dust}, journal = {Frontiers in Ecology and the Environment}, volume = {8}, year = {2011}, pages = {423-430}, abstract = {Wind erosion and associated dust emissions play a fundamental role in many ecological processes and provide important biogeochemical connectivity at scales ranging from individual plants up to the entire globe. Yet, most ecological studies do not explicitly consider dust-driven processes, perhaps because most relevant research on aeolian (wind-driven) processes has been presented in a geosciences rather than an ecological context. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the scale of plants and surrounding space to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. It is likely that changes in climate and intensification of land use will lead to increased dust production from many drylands. To address these issues, environmental scientists, land managers, and policy makers need to consider wind erosion and dust emissions more explicitly in resource management decisions.}, keywords = {aeolian processes, biogeochemistry, climate change, disturbance, drylands, dust, dust emissions, dust flux, ecological processes, ecosystem dynamics, land use, resource management, wind erosion}, doi = {10.1890/090050}, author = {J. P. Field and Jayne Belnap and David D. Breshears and J. Neff and Gregory S. Okin and J. J. Whicker and Painter, T. H. and S. Ravi and Reheis, M. C. and Reynolds, R. L.} } @article {50024, title = {Assessing transportation infrastructure impacts on rangelands: Test of a standard rangeland assessment protocol}, journal = {Rangeland Ecology and Management}, volume = {63}, year = {2010}, month = {07/2010}, pages = {524-536}, chapter = {524}, abstract = {

Linear disturbances associated with on and off-road vehicle use on rangelands has increased dramatically throughout the world in recent decades. This increase is due to a variety of factors including increased availability of all-terrain vehicles, infrastructure development (oil, gas, renewable energy, and ex-urban) and recreational activities. In addition to the direct impacts of road development, the presence and use of roads may alter resilience of adjoining areas through indirect effects such as altered site hydrologic and eolian processes, invasive seed dispersal, and sediment transport. There are few standardized methods for assessing impacts of transportation-related land-use activities on soils and vegetation on arid and semi-arid rangelands. Interpreting Indicators of Rangeland Health (IIRH) is an internationally accepted qualitative assessment that is applied widely to rangelands. We tested the sensitivity of IIRH to impacts of roads, trails, and pipelines on adjacent lands by surveying plots at three distances from these linear disturbances. We performed tests at 16 randomly selected sites in each of 3 ecosystems (Northern High Plains, Colorado Plateau, and Chihuahuan Desert) for a total of 208 evaluation plots. We also evaluated the repeatability of IIRH when applied to road-related disturbance gradients. Finally, we tested the extent to which IIRH plot attribute departure classes are correlated with trends in a suite of quantitative indicators. Results indicated that the IIRH technique is sensitive to direct and indirect impacts of transportation activities. Trends in degradation detected with qualitative assessments were highly correlated with quantitative data. Qualitative and quantitative assessments employed in this study can be used to assess impacts of transportation features at the plot scale. Through integration with remote sensing technologies, these methods could also potentially be used to assess cumulative impacts of transportation networks at the landscape scale.

}, keywords = {disturbance, IIRH, indicators, off-highway vehicles, oil and gas, rangeland health, roads}, doi = {10.2111/REM-D-09-00176.1}, url = {/files/bibliography/10-024.pdf}, author = {Danielle Duni and Jeffrey E. Herrick and D.A. Pyke and David P. Toledo} } @article {50094, title = {Animal disturbances promote shrub maintenance in a desertified grassland}, journal = {Journal of Ecology}, volume = {97}, year = {2009}, note = {//NMSU,USDA//LTER V//entered 10/14/2009; pdf available}, month = {2009}, pages = {1302-1310}, chapter = {1302}, abstract = {

Soil disturbance by animals affects the availability of water, nutrients, sediment and seeds, which are critical for the maintenance of functional ecosystems. We examined long-lived faunal structures across six vegetation communities in the northern Chihuahuan desert of New Mexico, USA, testing the proposition that disturbances in undesertified grassland differ in magnitude and effect from those in desertified grassland.\  Vertebrate and invertebrate disturbances totalled 18.9 structures ha)1 across 18 sites. The most common were pits and mounds of American badgers (Taxidea taxus, 32\%), nests of the ant Aphaenogaster cockerelli (18.8\%) and mounds of kangaroo rats (Dipodomys spectabilis, 31\%).\  Desertification was associated with a doubling of the density of structures, but no effects on cover or volume. The greatest density was in desertified mesquite and creosote bush shrublands, and the lowest density in undesertified grass swales. Badger and wood rat (Neotoma sp.) mounds were significant indicators of desertified communities. Desertification did not affect the density of kangaroo rat mounds (6.7 ha)1 in black grama grasslands and creosote bush shrublands). However, mounds in creosote bush shrubland were smaller and had more and larger shrubs than adjacent inter-mound hummocks. Desertification was associated with increases in the density of Aphaenogaster cockerelli and Trachymyrmex smithii nests, and declines in Pogonomyrmex rugosus nests. Substantial increases in soil nitrate and electrical conductivity on Myrmecocystus nests were associated with desertification. Synthesis. Desertification shaped this desert environment in two main ways. First, while kangaroo rat mound density changed little with desertification, mounds in shrubland continued to enhance shrub persistence long after abandonment, reinforcing desertification processes. Second, marked changes in the density of nests of the key ant species altered the spatial distribution of soil nitrate and electrical conductivity, likely affecting soil fertility and the distribution of desert plants. Our results highlight the importance of animal activity in shaping desert plant communities, and in maintaining or reinforcing desertification processes.

}, keywords = {animal activity, article, Biopedturbation, Chihuahuan Desert, desertification, disturbance, ecosystem engineering, journal, pedogenesis}, doi = {10.1111/j.1365-2745.2009.01558.x}, url = {/files/bibliography/10-036.pdf}, author = {D.J. Eldridge and Walter G. Whitford and B.D. Duval} } @article {50092, title = {Badger (Taxidea taxus) disturbances increase soil heterogeneity in a degraded shrub-steppe ecosystem}, journal = {Journal of Arid Environment}, number = {73}, year = {2009}, month = {01/2009}, pages = {66-73}, chapter = {66}, abstract = {

In the western United States, overgrazing, weed invasion and wildfire have resulted in the conversion of shrub-steppe to annual grasslands, with substantial effects on ecosystem function. In these lands capes, badgers disturb large areas of soil while foraging for fossorial animals. Mounds created by badgers contained the lowest concentrations of total carbon, nitrogen and sulphur, mineral nitrogen and mineralizable nitrogen, inter-mound soils had the highest concentrations, and excavation pits had intermediate levels. Soil C:N ratio and pH were greater, and electrical conductivity and soluble Ca2{\th}, Mg2{\th} and K{\th} were lower on mound soils compared with either pit or inter-mound soils. Larger pits generally trapped more litter, and increased litter mass equated with greater concentrations of active carbon, but only at the burned sites. Older mounds supported more vascular plants and cryptogamic crusts. Our results demonstrate reduced levels of nutrients and a higher C:N ratio on the mounds compared with either the pits or inter-mounds. Alteration to the homogeneous post-fire landscape by badgers contributes to patchiness in soils and vegetation, which is critical to the functioning of arid systems. Given their effect on soil C:N ratios, mounds may be important sites for recovery of indigenous shrub-steppe plant species.

}, keywords = {Badger, Biopedturbation, disturbance, ecosystem engineering, mounding, soil nutrients}, doi = {10.1016/j.jaridenv.2008.09.004}, url = {/files/bibliography/09-002.pdf}, author = {D.J. Eldridge and Walter G. Whitford} } @article {50409, title = {Impacts of biological soil crust disturbance and composition on C and N loss from water erosion}, journal = {Biogeochemistry}, volume = {77}, year = {2006}, month = {01/2006}, pages = {247-263}, chapter = {247}, abstract = {

In this study, we conducted rainfall simulation experiments in a cool desert ecosystem to examine the role of biological soil crust disturbance and composition on dissolved and sediment C and N losses. We compared runoff and sediment C and N losses from intact latesuccessional dark cyanolichen crusts (intact) to both trampled dark crusts (trampled) and dark crusts where the top 1 cm of the soil surface was removed (scraped). In a second experiment, we compared C and N losses in runoff and sediments in early-successional light cyanobacterial crusts (light) to that of intact late-successional dark cyanolichen crusts (dark). A relatively high rainfall intensity of approximately 38 mm per 10-min period was used to ensure that at least some runoff was generated from all plots. Losses of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonium (NH4 + ) were significantly higher from trampled plots as compared to scraped and intact plots. Sediment C and N losses, which made up more than 98\% of total nutrient losses in all treatments, were more than 4-fold higher from trampled plots relative to intact plots (sediment C g/m2, intact = 0.74, trampled = 3.47; sediment N g/m2, intact = 0.06, trampled = 0.28). In light crusts, DOC loss was higher relative to dark crusts, but no differences were observed in dissolved N. Higher sediment loss in light crusts relative to dark crusts resulted in 5-fold higher loss of sediment-bound C and N. Total C flux (sediment + dissolved) was on the order of 0.9 and 7.9 g/m2 for dark and light crusts, respectively.\  Sediment N concentration in the first minutes after runoff from light crusts was 3-fold higher than the percent N of the top 1 cm of soil, suggesting that even short-term runoff events may have a high potential for N loss due to the movement of sediments highly enriched in N. Total N loss from dark crusts was an order of magnitude lower than light crusts (dark = 0.06 g N/m2, light = 0.63 g/m2). Overall, our results from the small plot scale (0.5 m2) suggest that C and N losses are much lower from intact late-successional cyanolichen crusts as compared to recently disturbed or early-successional light cyanobacterial crusts.

}, keywords = {Biological soil crust, Canyonlands National Park, carbon, Colorado Plateau, disturbance, erosion, nitrogen, rainfall simulation, runoff}, doi = {10.1007/s10533-005-1424-7}, url = {/files/bibliography/06-070.pdf}, author = {N. Barger and Jeffrey E. Herrick and Justin Van Zee and Jayne Belnap} } @article {50411, title = {Effects of Feral Horses in Great Basin Landscapes on Soils and Ants: Direct and Indirect Mechanisms}, journal = {Journal of Arid Environments}, volume = {66}, number = {1}, year = {2006}, month = {January 2006}, pages = {96-112}, abstract = {We compared soil-surface penetration resistance and abundance of ant mounds at 12 western Great Basin sites (composed of 19 plots) either grazed by feral horses (Equus caballus) or having had horses removed for the last 10\–14 years. Across this broad spatial domain (3.03 million ha), we minimized confounding due to abiotic factors by selecting horse-occupied and horse-removed sites with similar aspect, slope, \&$\#$39;re history, grazing pressure by cattle (minimal to none), and dominant vegetation (Artemisia tridentata). During both 1997 and 1998, we found 2.2\–8.4 times greater abundance of ant mounds and 3.0\–15.4 times lower penetration resistance in soil surfaces at horse removed sites. In 1998, thatched Formica ant mounds, which existed predominately at high elevations, were 3.3 times more abundant at horse-removed sites, although abundance varied widely among sites within treatments. Several types of analyses suggested that horses rather than environmental variability were the primary source of treatment differences we observed in ecosystem components. Tests of several predictions suggest that alterations occurred through not only direct effects, but also indirect effects and potentially feedback loops. Free-roaming horses as well as domestic grazers should be considered in conservation planning and land management in the Great Basin, an ecoregion that represents both an outstanding conservation opportunity and challenge. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4HWX8YM-1-17\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=07\%2F31\%2F2006\&_sk=999339998\&view=c\&wchp=dGLzVzz-zSkzS\&md5=1d287ea8843005be3bea26ad74d18846\&ie=/sdarticle.pdf}, keywords = {conservation, disturbance, Equus caballus, feral horses, formica, Nevada, pogonomyrmex}, url = {/files/bibliography/06-025.pdf}, author = {E.A. Beever and Jeffrey E. Herrick} } @article {50721, title = {Soil disturbance by soil animals on a topoclimatic gradient}, journal = {European Journal of Soil Biology}, volume = {40}, number = {2}, year = {2004}, month = {August 6, 2004}, pages = {73-76}, abstract = {

We measured the area and volume of soil disturbed by various groups of animals at three sites on a topoclimatic gradient in the Judean Desert, Israel. Both the area and volume of soil disturbed by animals correlated with the cumulative precipitation of the winter rain season. Rodent activity accounted for most of the soil disturbance at all sites except for June 2001, when the volume of soil transported to the surface by ants in the construction of nest chambers accounted for most of the soil volume moved at the intermediate rainfall site. The aggregate stability of soil ejected from animal excavations was significantly lower than that of undisturbed soil during and immediately following the winter rain season, but not during the following dry seasons. The quantities of soil moved by ants in the Judean Desert were comparable to quantities moved by ants in the Chihuahuan Desert of North America.

}, keywords = {disturbance, gradient, measure, soil, topoclimatic, volume}, doi = {10.1016/j.ejsobi.2004.07.001}, url = {/files/bibliography/04-078.pdf}, author = {Yosef Steinberger and Pen-Mouratov, S. and Walter G. Whitford} } @article {50789, title = {Desertification and biopedturbation in the northern Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {53}, number = {1}, year = {2003}, month = {January 1, 2003}, pages = {1-14}, abstract = {

We examined the relationship between biopedturbation (animal-caused soil disturbance) and several vegetation and soil-based indicators of rangeland condition to evaluate the effects of desertification on animal soil disturbance. The area, volume, and abundance of various biopedturbation types were assessed at 117 sites in south-central New Mexico where vegetative cover and composition had previously been measured. There were significant relationships between biopedturbation and selected rangeland condition indicators. Increasing percentages of grass cover were positively associated with increasing total area of biopedturbation. Increasing percentages of shrub cover and mean bare patch size were negatively associated with total biopedturbation area. Biopedturbation area and volume were related to indicators of rangeland condition and percent shrub cover best predicts the area of soil disturbed by animals. This relationship, however, cannot reliably predict total biopedturbation area or the area of soil disturbance types.

}, keywords = {Biopedturbation, Chihuahuan Desert, condition indicators, desertification, disturbance, rangeland, soil}, doi = {10.1006/jare.2002.1022}, url = {/files/bibliography/03-009.pdf}, author = {E. Jackson and Krogh, S.N. and Walter G. Whitford} } @conference {51081, title = {Relationship between soil organic matter dynamics and disturbance regime and applications to monitoring and modelling vegetation change}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 8-10, 200}, pages = {404}, address = {Snowbird, UT}, abstract = {Soil organic matter is widely cited as a key ecosystem property which both affects and reflects water and nutrient storage and redistribution. Relationships between soil organic matter and soil structure in arid ecosystems and the effects of soil biota and disturbance are poorly understood. Our research is designed to develop an understanding of how interactions between plants, soil organic matter and soil biota affect patch-scale soil water infiltration and storage under different disturbance regimes and how variability in these processes across the landscape contributes to resource redistribution and vegetation patterns. We are applying this understanding to the development of (1) a quantitative monitoring system for grassland, shrubland and savanna ecosystems, (2) a spatially interactive gap dynamics model (ECOTONE see Peters and Herrick poster), and (3) ecologically-based remediation approaches for degraded rangeland. Our results show termites, ants and microbiotic crusts contribute significantly to the spatial variability of water infiltration and runoff and the resistance and resilience of soil properties and processes are strongly dependent on both soil type and the soil biotic community. The monitoring system includes a suite of rapid soil and vegetation indicators selected and applied on a site-specific basis and interpreted in a landscape context.}, keywords = {disturbance, interactions, modelling, monitoring, organic matter, resource redistribution, soil, vegetaton patterns}, author = {Jeffrey E. Herrick} } @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} } @article {51144, title = {Burrowing activities of kangaroo rats and patterns in plant species dominance at a shortgrass steppe-desert grassland ecotone}, journal = {Journal of Vegetation Science}, volume = {10}, year = {1999}, month = {1999}, pages = {123-130}, abstract = {

Our objective was to evaluate the effects of burrowing activities by banner-tail kangaroo rats (Dipodomys spectabilis Merriam) on plant community structure and species dominance for two patch types at the ecotone between shortgrass steppe and desert grassland in New Mexico, USA. 10 mounds produced by kangaroo rats were selected in patches dominated by Bouteloua gracilis (the dominant in shortgrass steppe communities) and 10 mounds were selected in patches dominated by B. eriopoda (the dominant in Chihuahuan desert grasslands). Plant cover and density by species were sampled from three locations associated with each mound: the mound proper, the edge of the mound in the transition area, and the off-mound vegetation. Similar cover of B. eriopoda for the edges of mounds in both patch types indicates the ability of this species to respond to animal disturbances regardless of the amount of cover in the surrounding undisturbed vegetation. By contrast, cover of B. gracilis was low for all mounds and mound edges in patches dominated by this species. Much higher cover of B. eriopoda on mound edges compared to the undisturbed vegetation in B. gracilis-dominated patches indicates that kangaroo rats have important positive effects on this species. Lower cover of perennial grasses and higher cover of forbs, shrubs, and succulents on the edges of mounds in B. eriopoda-dominated patches compared to patches dominated by B. gracilis indicate the importance of surrounding vegetation to plant responses on disturbed areas.

}, keywords = {Bouteloua, Chihuahuan Desert, Dipodomys spectabilis, disturbance, dominant species, kangaroo rat}, doi = {10.2307/3237167}, url = {/files/bibliography/654.pdf}, author = {Fields, M.J. and D.P. Coffin and J. R. Gosz} } @article {51201, title = {Biopedturbation by mammals in deserts: A review}, journal = {Journal of Arid Environments}, volume = {41}, number = {2}, year = {1999}, month = {February 1, 1999}, pages = {203-230}, abstract = {

Disturbance-caused patchiness is important for development and maintenance of spatial and temporal heterogeneity in ecosystems. Mammals are important agents of biopedturbation (soil disturbance by organisms) which is a major source of patchiness in arid ecosystems. The contribution of soil disturbance by mammals to heterogeneity is a function of the size and longevity of the soil disturbance. Foraging pits produced by a variety of mammals are relatively short-lived features that trap plant litter and seeds that are rapidly buried. These form nutrient-rich germination sites. High water infiltration rates, a low bulk density rooting environment, and frequently increased soil nutrient content (especially mounds of central-place foragers and larder-hoarders) characterize warren complexes. Productivity tends to be higher on these mounds and the vegetation tends to differ in composition and richness from the surrounding areas. Soil ejected from fossorial mammal burrow systems is generally of low bulk density, erodes readily, and varies greatly with respect to concentration of nutrients and organic matter depending upon the species and landscape in which the species lives. The variability in soil properties of fossorial burrow system ejecta mounds precludes generalizations about the effects of these disturbances on vegetation. Long-lived features such as Mima-like mounds and heuweltjies are nutrient-rich features that support high productivity and a distinct floral assemblage. There is a significant relationship between longevity of mammal soil disturbance and size of the disturbance: longevity in years=9.33 Area0.735. The data suggest that pedturbation by mammals can be an important force in pedogenesis, in structuring landscapes, and in maintaining heterogeneity in ecosystems. Data on mammalian pedturbation is based on scattered autecological studies. There is a need for long-term studies that focus on biopedturbation (soil disturbance by invertebrates and vertebrates) as a process at scales from the patch to the landscape.

}, keywords = {Biopedturbation, burrows, deserts, disturbance, fossorial rodents, patch dynamics, small mammals, soil properties}, doi = {10.1006/jare.1998.0482}, url = {/files/bibliography/696.pdf}, author = {Walter G. Whitford and F. R. Kay} } @article {51197, title = {Using resistance and resilience measurements for {\textquoteleft}fitness{\textquoteright} tests in ecosystem health}, journal = {Journal of Environmental Management}, volume = {57}, number = {1}, year = {1999}, month = {September 1, 199}, pages = {21-29}, abstract = {

The resistance and resilience of perennial grasses and a small shrub to a natural disturbance (drought) were measured on stress gradients that were produced by domestic livestock in desert grassland ecosystems in the northern Chihuahuan Desert of New Mexico, USA. Both survivorship of grasses and a sub-shrub (Gutierrezia sarothrae) during a drought (a measure of resistance) and re-establishment of plant cover following a drought (a measure of resilience) were reduced in the intensely stressed ecosystems in comparison to the lightly stressed ecosystems. The compromise of the resistance and resilience characteristics of an ecosystem can be used as a {\guillemotleft}fitness{\guillemotright} test for the health of ecosystems. Fitness tests can provide early warning of ecosystem degeneration and allow intervention to reduce or eliminate anthropogenic stress on the ecosystems.

}, keywords = {disturbance, ecosystem health, fitness test, grazing, resilience, resistance, stress, survivorship}, doi = {10.1006/jema.1999.0287}, url = {/files/bibliography/534.pdf}, author = {Walter G. Whitford and D. J. Rapport and A.G. de Soyza} }