@conference {JRN55304, title = {Feeding habits of Brangus and Raramuri Criollo cows grazing Chihuahuan Desert rangeland}, booktitle = {Society for Range Management Meeting Abstracts}, year = {2021}, month = {02/15/2021}, abstract = {Heritage cattle breeds may help improve sustainability of ranching in the arid Southwest. Foraging behavior of Raramuri Criollo (RC, heritage breed) and Brangus (BR) cows was observed to determine whether breeds differ in the amount of browse included in their diets. Cattle were monitored by a single observer who scan sampled groups of 3 to 16 animals at 30 second intervals for 30 minutes during morning and afternoon foraging bouts to determine frequency of grazing vs. browsing. To the best of the observer{\textquoteright}s ability cattle were undisturbed while monitoring. Observations were conducted on 29 or 23 days in spring and summer, respectively. A total of 5,824 (3,521 RC, 2,303 BR) and 7,120 (3,429 RC, 3,691 BR) in spring and summer, respectively, were summarized and analyzed. Analysis of Variance using PROC GLM in SAS 9.4 to determine the effect of breed and season on frequency of browsing and grazing of cattle in this study. LS means were compared using the Tukey-Kramer test. We found a significant breed-by-season interaction for browsing (P< 0.01) and grazing (P< 0.01) frequency, therefore breed differences in feeding habits depended on the season considered. In spring, RC cows were observed browsing more often (64.4 \%; P = 0.08) and grazing less often (35.6\%; P = 0.08) than BR cows (browsing: 29.7\%; grazing: 70.3\%). In summer, no differences between breeds were observed (P > 0.10). RC were observed browsing more often (P=0.02) and grazing less often (P= 0.02) in spring than in summer whereas BR showed no statistically detectable seasonal differences in grazing and browsing frequency (P > 0.1). Our results, while preliminary, suggest that relative to BR, heritage cows grazing Chihuahuan Desert rangeland include more browse in their diets during spring and exhibit higher seasonal plasticity of feeding habits.}, author = {Danielle Duni and Andr{\'e}s F. Cibils and Richard E. Estell and Andrew Cox and Matthew M. McIntosh and S. Spiegal} } @article {JRN54904, title = {Soil water dynamics at 15 locations distributed across a desert landscape: insights from a 27-yr dataset}, journal = {Ecosphere}, volume = {9}, year = {2018}, month = {07/2018}, pages = {36 pp}, abstract = {

Desert ecosystems are primarily limited by water availability. Within a climatic regime, topography, soil characteristics, and vegetation are expected to determine how the combined effects of precipitation, temperature, and evaporative demand of the atmosphere shape the spatial and temporal patterns of water within the soil profile and across a landscape. To forecast how desert landscapes may respond to future climatic conditions, it is imperative to improve our understanding of these ecohydrologic processes. Here, we report on 27 yr of monthly soil volumetric water content (VWC) measurements and associated soils data from a site in the northern Chihuahuan Desert of North America. The dataset includes VWC and soil properties measured to 3 m in depth across 15 locations that encompass a range of Chihuahuan Desert vegetation types. We use this unique dataset (1) to generate insights into general temporal and depth patterns in VWC, (2) to analyze how VWC corresponds to measures of climatic conditions, and (3) to qualitatively evaluate the relative importance of soils, topographic setting, and vegetation type in mediating temporal patterns in VWC. Analyses of this unique dataset emphasize the importance of soil and topographic setting in determining depth and temporal patterns in VWC across time. Results emphasize the episodic nature of deep wetting events in our study system{\textemdash}essentially limited to three large events over the 27-yr record driven primarily by wetter than normal winters. Comparison of soil water dynamics between mesquite shrub coppice dunes and interspace soils suggests the {\textquotedblleft}island of fertility{\textquotedblright} concept does not extend to soil water. Median VWC was strongly coupled to climatic conditions over surprisingly long windows at most locations (6{\textendash}18 months), suggesting that soil water at depth is decoupled from short climatic pulses. However, VWC dynamics and VWC{\textendash}climate relationships varied among locations, depths, and seasons, with unexpected similarities in ecohydrologic dynamics observed among very different vegetation types (e.g., an eroded creosote shrubland and a playa grassland). These results further underscore the importance of ecohydrological investigations in these ecosystems, given forecasts for a warmer and more variable climate in deserts globally.

}, keywords = {Chihuahuan Desert, coppice dunes, critical zone, deep recharge, desertification, ecohydrology, grassland, landscape context, neutron moisture meter, shrubland, soil water, Special Feature: Dynamic Deserts, vadose zone}, doi = {e02335. 10.1002/ecs2.2335}, url = {files/bibliography/18-013.pdf}, author = {Danielle Duni and Matthew D. Petrie and Debra C. Peters and John P. Anderson and K. Crossland and Jeffrey E. Herrick} } @article {JRN54686, title = {Generalizing ecological site concepts of the Colorado Plateau for landscape-level applications}, journal = {Rangelands}, volume = {38:342-349}, year = {2016}, month = {12/2016}, abstract = {

The Colorado Plateau is an iconic landscape of the American West{\textemdash} containing dozens of national parks, monuments, historic sites, and several UNESCO World Heritage Sites{\textemdash} including some of the Nation{\textquoteright} s most recognizable landmarks, such as the Grand Canyon and the Arches National Park. The concentration of outdoor destinations has led to a rapid increase in recreational tourism on the Plateau{\textemdash} visitation to the Arches National Park has nearly doubled over the last 15 years. \ Energy development (mostly oil and gas) has also accelerated in recent years, with a threefold increase in drilling rates in Utah between 2000 and 2008. Agriculture has been an important activity in the region from the prehistoric ages to modern times, with irrigated agriculture carried out in locations with suitable soils and water and domestic livestock grazing (primarily cattle) occurring across the majority of the region. Management of these co-occurring land uses are complicated by forecasts of a more arid and variable climate in the southwestern United States.

}, doi = {10.1016/j.rala.2016.10.010}, url = {files/bibliography/16-036.pdf}, author = {Danielle Duni and Travis Nauman and J. Johansen and Green, Shane and M. Miller and Jebediah C. Williamson and Brandon T Bestelmeyer} } @article {49846, title = {Assessing impacts of roads: Application of a standard assessment protocol}, journal = {Rangeland Ecology and Management}, volume = {66}, year = {2013}, month = {05/2013}, pages = {364-375}, chapter = {364}, abstract = {

Adaptive management of road networks depends on timely data that accurately reflect the impacts of network impacts on ecosystem processes and associated services. In the absence of reliable data, land managers are left with little more than observations and perceptions to support adaptive management of road-associated disturbances. Roads can negatively impact the soil, hydrologic, plant, and animal processes on which virtually all ecosystem services depend. The Interpreting Indicators of Rangeland Health (IIRH) protocol is a qualitative method that has been demonstrated to be effective in characterizing impacts of roads. The goals of this study were to develop, describe, and test an approach for using IIRH to systematically evaluate road impacts across large, diverse arid and semiarid landscapes. We developed a stratified random sampling approach to plot selection based on ecological potential, road inventory data, and image interpretation of road impacts. The test application on a semi-arid landscape in southern New Mexico, USA demonstrates that the approach developed is sensitive to road impacts across a broad range of ecological sites but that not all the types of stratification were useful. Ecological site and road inventory strata accounted for significant variability in the functioning of ecological processes but stratification based on apparent impact did not. Analysis of the repeatability of IIRH applied to road plots indicates that the method is repeatable but consensus evaluations based multiple observers should be used to minimize risk of bias. Landscape-scale analysis of impacts by roads of contrasting designs (maintained dirt or gravel roads versus non- or infrequently maintained roads) suggests that future travel management plans for the study area should consider concentrating traffic on fewer roads that are well-designed and maintained. Application of the approach by land managers will likely provide important insights into minimizing impacts of road networks on key ecosystem services.

}, keywords = {adaptive management, assessment, monitoring, off-highway vehicles, oil and gas, rangeland health}, doi = {10.2111/REM-D-11-00130.1}, url = {/files/bibliography/13-018.pdf}, author = {Danielle Duni and Jeffrey E. Herrick} } @article {49879, title = {Rangeland and pasture monitoring: an approach to interpretation of high-resolution imagery focused on observer calibration for repeatability}, journal = {Environmental Monitoring and Assessment}, volume = {184}, year = {2012}, month = {07/23/2011}, pages = {3789-3804}, chapter = {3789}, abstract = {

Collection of standardized assessment and monitoring data is critically important for supporting policy and management at local to continental scales. Remote sensing techniques, including image interpretation, have shown promise for collecting plant community composition and ground cover data efficiently. More work needs to be done, however, evaluating whether these techniques are sufficiently feasible, cost-effective, and repeatable to be applied in large programs. The goal of this study was to design and test an image-interpretation approach for collecting plant community composition and ground cover data appropriate for local and continental-scale assessment and monitoring of grassland, shrubland, savanna, and pasture ecosystems. We developed a geographic information system image-interpretation tool that uses points classified by experts to calibrate observers, including point-by-point training and quantitative quality control limits. To test this approach, field data and high-resolution imagery (\~{}3 cm ground sampling distance) were collected concurrently at 54 plots located around the USA. Seven observers with little prior experience used the system to classify 300 points in each plot into ten cover types (grass, shrub, soil, etc.). Good agreement among observers was achieved, with little detectable bias and low variability among observers (coefficient of variation in most plots \<0.5). There was a predictable relationship between field and image-interpreter data (R (2) \> 0.9), suggesting regression-based adjustments can be used to relate image and field data. This approach could extend the utility of expensive-to-collect field data by allowing it to serve as a validation data source for data collected via image interpretation.

}, keywords = {aerial photography, assessment and monitoring, image interpretation, large-scale, remote sensing, repeatability}, doi = {10.1007/s10661-011-2224-2}, url = {/files/bibliography/12-005.pdf}, author = {Danielle Duni and Jason W. Karl and Scott T. Schrader and Noemi Baquera and Jeffrey E. Herrick} } @article {49942, title = {Disentangling road network impacts: the need for a holistic approach}, journal = {Journal of Soil and Water Conservation}, volume = {66}, year = {2011}, month = {April 2011}, pages = {31A-36A}, chapter = {31A}, doi = {10.2489/jswc.66.2.31A}, url = {/files/bibliography/11-003.pdf}, author = {Danielle Duni and Jeffrey E. Herrick} } @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} } @conference {JRN54453, title = {Climate-soil interactions: global change, local properties, and ecological sites}, booktitle = {63rd Society for Range Management Annual Meetings}, year = {2010}, month = {02/07/2010}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Denver, CO}, abstract = {

Global climate change is predicted to alter historic patterns of precipitation and temperature in rangelands globally. Vegetation community response to altered weather patterns will be mediated at the site level by local-scale properties that govern ecological potential, including geology, topography and soils. Broad patterns in these local-scale properties are currently used in the ecological site concept as a method for classifying the landscape into relatively homogeneous units within current climatic zones. Although present vegetation distributions are often used when developing concepts for new ecological sites, the range of variation in soils, topography and geology that ultimately differentiate ecological sites often accounts for many of the local-scale properties likely important for mediating plant community responses to climate change. Barring dramatic rearrangement of landscapes, many of the combined soil-topographic-geologic properties used in ecological site delineation are not likely to change in time scales relative to management. Knowledge of processes governed by these site properties can be used to improve our understanding of climate-vegetation relationships in state-and-transition models. We review dynamic and static site properties important for mediating impacts of climate change and provide examples illustrating how understanding of site dynamics associated with these properties can add to the knowledge necessary for developing ecological site descriptions that can accommodate climate change effects. Finally, we present challenges and opportunities of using an ecological site based approach for making results of climate change studies relevant to managers concerned about climate change. Abstract $\#$ SYM-108.

}, author = {Danielle Duni and Brandon T Bestelmeyer} } @article {50023, title = {Soil processes and properties that distinguish ecological sites and states}, journal = {Rangelands}, volume = {32}, year = {2010}, month = {12/2010}, pages = {9-15}, chapter = {9}, abstract = {

Differences in ecological sites, and sometimes ecological states, are ultimately due to differences in soil properties and processes within a climatic zone. Soil properties are features of a soil, such as soil texture or soil depth.\  Soil processes are a series of actions in the soil that bring about a result, for example, water percolating into the soil that determines soil water amounts. Measured relationships between soil properties and soil processes allow us to estimate soil processes given information on a set of soil properties and other variables, such as rainfall amounts. For example, we can predict the rate at which water will percolate into a soil profile if we have data on soil properties such as texture, soil structure, bulk density, and organic matter. How do we determine which soil properties and processes differ among ecological sites or ecological states?\  This is typically done by observing relationships between soils and the plant communities occurring on them.\  We inventory plant communities and soil properties within a climatic zone and look for statistical relationships among them. We then draw on research to infer the soil processes that occur and develop hypotheses about how those processes explain plant community patterns.\  Although soil and landform properties are used to describe the characteristics of ecological sites, it is the soil processes that are controlled by the properties that actually cause differences between ecological sites. Soil processes explain why ecological sites (and sometimes states) differ. The goal of this article is to equip developers and users of ecological site descriptions with a basic understanding of how differences in soils arise, the relationship between soil maps and ecological sites, and how soil properties affect soil processes to create differences among ecological sites and states. Our hope is that this understanding can be used to guide data collection and help develop narratives to explain the properties of ecological sites and states.

}, doi = {10.2111/RANGELANDS-D-10-00090.1}, url = {/files/bibliography/10-043.pdf}, author = {Danielle Duni and Brandon T Bestelmeyer and A.J. Tugel} } @article {50022, title = {Spatial and temporal patterns of water availability in a grass-shrub ecotone and implications for grassland recovery in arid environments}, journal = {Ecohydrology}, volume = {3}, year = {2010}, pages = {55-67}, abstract = {

Encroachment of woody shrubs into historic desert grasslands is a major problem throughout the world. Conversion of grasslands to shrub-dominated systems may result in significant alteration of biogeochemical processes and reduced resource availability in shrub interspaces, making grassland recovery difficult. Soil petrocalcic horizons, which are common in arid and semiarid regions globally, have been shown to dramatically alter plant water availability. To assess how soil water dynamics are affected by woody encroachment in petrocalcic soils under contrasting precipitation patterns, we conducted a three year replicated study in a mixed shrub-grass system measuring soil water in unvegetated interspaces and under mesquite canopies. Plots were instrumented with TDR moisture probes, both above and within the soil petrocalcic horizon. Soils in both vegetation strata maintained large increases in available water content for several months during a wetter than normal winter and summer (increases of 0.08 to 0.16 m3 m-3). Interspace soils absorbed significantly greater quantities of water during the winter and retained more water into the spring than soils under shrubs. In contrast, soils under shrubs initially absorbed greater volumes of water during and following summer rains. Differing seasonal dynamics were attributed to interactions between the unique properties of soils with petrocalcic horizons and canopy induced variability in evapotranspiration. Observed patterns of plant available water do not support the hypothesis of greater resource availability under shrubs. Similar or greater water availability in shrub interspaces indicates that concentration of soil water under shrubs may not be a process limiting grass recovery on these soils.

}, keywords = {biogeochemical, grass-shrub, journal, patterns, shrub-dominated, spatial, temporal}, doi = {10.1002/eco.94}, url = {/files/bibliography/10-01.pdf}, author = {Danielle Duni and K. A. Snyder and Jeffrey E. Herrick} } @article {50021, title = {Spatial and temporal variability of plant-available water in calcium carbonate-cemented soils and consequences for arid ecosystem resilience}, journal = {Oecologia}, volume = {163}, year = {2010}, note = {August 14, 2008-Ecology; resubmitted to Oecologia 3-19-2009 w/new title}, pages = {215-226}, chapter = {215}, abstract = {

Increased variability in precipitation, including frequency of drought, is predicted for many arid and semiarid regions of the world. The ability of soils to retain water can increase resilience by buffering vegetation communities against precipitation extremes. Little is known, however, about water retention by carbonate cemented soil horizons, which occur extensively in arid and semiarid ecosystems. It has been speculated that they may significantly modify vertical and temporal distribution of plant-available water (PAW). To investigate this hypothesis, PAW was monitored at three sites in a mixed shrub-grass community in southern New Mexico, USA, across soils with differing degrees of carbonate horizon development: no carbonate horizon, a partially cemented calcic horizon, and a continuously cemented petrocalcic horizon. Results are presented from three years that included extremely dry and wet periods. Calcic and petrocalcic horizons absorbed and retained significantly greater amounts of PAW for several months following an extremely wet winter and summer compared to the non-carbonate soil. Following a wet summer, petrocalcic horizons retained very high PAW (16 to 18\% volumetric or ~72 to 80\% of soil water holding capacity) through early spring of the following year, more than double the PAW retained by similar depths in the non-carbonate soil. Drying dynamics indicate calcic and petrocalcic horizons release stored water into the grass rooting zone during growing seasons following extreme events. Water dynamics of calcic and petrocalcic horizons during extreme events provide a mechanism to explain previous observations that perennial grasses exhibit greater resilience to drought when high carbonate horizons occur at shallow depths (\< 50 cm). Water holding capacity of the entire profile, including rock-like material such as calcium carbonate, should be considered when evaluating the potential resilience of vegetation communities to disturbance, including the increased variability in precipitation expected to occur as a result of global climate change.

}, keywords = {calcic, Chihuahuan Desert, climate change, desert grassland, ecosystem, horizon, Petrocalcic, precipitation}, doi = {10.1007/s00442-009-1530-7}, url = {/files/bibliography/10-03.pdf}, author = {Danielle Duni and Jeffrey E. Herrick and Curtis H. Monger} } @conference {JRN54454, title = {A suite of tools for monitoring and assessing impacts of road networks and off-road vehicle activity on rangelands }, booktitle = {63rd Society for Range Management Annual Meetings}, year = {2010}, month = {02/2010}, publisher = {Sociiety for Range Management}, organization = {Sociiety for Range Management}, address = {Denver, CO}, abstract = {

Despite increasing amounts of transportation related activities on rangelands globally, few tools exist for assessing and monitoring impacts of roads, road networks and off-road vehicle traffic. This is in part due to an historical emphasis on grazing issues in rangelands and the complexity of monitoring and assessing impacts of roads and vehicles on rangeland health and productivity. We present strategies for applying new and existing tools to monitoring and assessment of road and off-road vehicle impacts at multiple spatial scales. Tools described include an adaptation of Interpreting Indicators of Rangeland Health, a checklist for describing hydrologic impacts, LIDAR analyses, laser rangefinders, and various types of penetrometers. We demonstrate how a currently available online application can help select appropriate assessment and monitoring methods and design cost-effective sampling systems. The suite of tools presented can potentially greatly increase our ability to detect road and vehicle associated impacts at multiple spatial scales, filling an important knowledge gap necessary for adaptive management of road and vehicle impacted rangelands. Abstract $\#$ PC-24.

}, author = {Danielle Duni and Jeffrey E. Herrick and Jason W. Karl and Justin Van Zee} } @conference {50090, title = {Impacts of a road network on a semiarid grassland}, booktitle = {Ecological Society of American Abstracts}, year = {2009}, month = {08/2009}, pages = {PS 82-81}, abstract = {

An unprecedented amount of road, trail, and other infrastructure development is currently occurring or planned for many arid and semiarid ecosystems nationally. This is due to a variety of factors, including energy resources development (oil, gas, wind, solar, coaled methane, and others), recreational off-road vehicle activity, exurban development and military training. Planning and mitigation necessary to protect these ecosystems require accurate identification of highest resilience areas, including those most resistant to degradation and those that have the greatest capacity to recover quickly following degradation. The objective of this study was to develop a strategy for assessing the long-term effects of different types of roads on adjacent soil and vegetation properties in a southern New Mexico grassland. To accomplish this objective, 110 plots selected within a 63,418 acres study area using a stratified random sampling scheme. Plots were stratified by soil type (5 levels) and road type (3 levels: no road, major road and minor road). Additionally, to maximize detection of problem areas, we further stratified our base set of road points based on apparent impact as determined by qualitative aerial photo interpretation. Vegetation cover, soil cover, and soil aggregate stability data were collected along three 25-m transects at each plot. Overall, roads had significant, negative impacts on adjacent soils and vegetation when compared to non-road areas. The severity of impacts varied with soil type suggesting that road and trail development should be carefully planned to avoid more sensitive soils. Results indicate that most negative impacts due to road and trail development in the study area occurred in map units dominated by fairly coarse, low water holding capacity soils. Differences were primarily driven by reduced plant productivity in road corridors as indicated by increased bare ground and decreased canopy cover. In some soil types, loss of soil stability in unprotected locations also appears to be an issue. Few significant differences in plant community composition were detected between road and non-road areas. The level of road development did not consistently affect results, suggesting that concentration of activity along a smaller set of major roads may be one strategy to reduce cumulative impacts. For some soil types, the qualitative stratification technique was important for detecting rare but important negative impacts. This study illustrates the importance of integrated soil and ecological inventory data for incorporating site specific resilience knowledge into planning processes.

}, keywords = {coaled methane, ecosystem, energy resources, gas, military, off-road vehicle, oil, recreational, road, solar, trail, wind}, author = {Danielle Duni and Jeffrey E. Herrick} } @conference {50089, title = {Multiscale variability of soil aggregate stability: implications for rangeland hydrology and erosion}, booktitle = {62nd Society for Range Mangement Annual Meeting}, year = {2009}, month = {February 8-12, 2}, pages = {07-11}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Alb., NM}, abstract = {Conservation of soil and water resources in rangelands is a crucial step in stopping desertification processes. The formation of water-stable soil aggregates reduces soil erodibility and can increase infiltration capacity in many soils. Soil aggregate stability is highly variable at scales ranging from individual aggregates to bioclimatic regions due to complex interactions of soil texture, soil organic matter, soil organisms, vegetation and surface disturbance. Variability in soil aggregate stability at all scales has important implications for rangeland hydrology and erosion. We conducted field soil aggregate stability tests at multiple scales (plot, landscape, and regional) throughout the western United States and in areas with varying degrees of vehicle-related disturbances. Additionally, small plot scale rainfall simulation experiments were conducted in conjunction with soil stability measures. Results demonstrate the scale-dependent nature of variability in soil aggregate stability, particularly within a disturbance gradient. The implications of this variability for hydrology and erosion are explored by contrasting variability in soil stability among scales, disturbance types and regions. Other site properties related to hydrology and erosion, including soil texture, vegetation, and cover and distribution bareground, are used to highlight possible mechanisms. In rangeland monitoring and assessment activities, the application of average soil stability values over large areas can be appropriate. Soil degradation at small scales, however, can result in disproportionally large increases in soil erosion and run-off. Results from our studies and related literature indicate that large variability occurring at relatively small scales should be considered for multi-scale estimates of changes in rangeland hydrology and erosion.}, keywords = {aggregate, desertification, hydrology, stability}, author = {Danielle Duni and Jeffrey E. Herrick and K. Spaeth and N. Barger and Justin Van Zee and Jayne Belnap} } @conference {50201, title = {Assessing resilience of western rangelands to transportation-related land-use change}, booktitle = {Geological Society of America}, series = {2008 Joint Meetings}, year = {2008}, month = {10/2008}, pages = {51-10}, address = {Houston, TX}, abstract = {

The amount and extent of transportation related activity in western rangelands has rapidly increased in recent decades. This increase is due to a variety of factors including oil and gas development, recreational activities, and ex-urban development. In addition to areas directly impacted by infrastructure installation, the presence and use of these travelways has potentially altered the resilience of adjoining areas through indirect effects such as altered site hydrologic and eolian processes, invasive seed dispersal, and sediment transport. Direct and indirect impacts of these networks are of particular concern in ecosystems with inherently low resilience, such as those with aridic soils. There is little guidance, however, on appropriate methods for assessing and monitoring the impacts of transportation related land-use activities on soils and vegetation. We tested the sensitivity of a qualitative assessment technique (Interpreting Indicators of Rangeland Health) and quantitative measures to roads, trails, and pipelines. The protocols used have a demonstrated connection to soil nutrient and moisture-related processes in a wide range of ecosystems. We conducted surveys at plots near, far and very far from travelways at 16 sites selected using a stratified random sampling design in 3 ecosystems for a total of 208 plots evaluated. Results indicate that qualitative techniques are sensitive to direct and indirect impacts of transportation activities. Additionally, differences detected with qualitative techniques between areas near, far and very far from disturbances followed the same trends and were highly correlated with quantitative measures. The qualitative and quantitative assessment techniques employed in this study can be used to assess impacts of individual transportation features or to assess cumulative impacts of a transportation network. Assessing how transportation related activities on western rangelands affects ecosystem resilience is crucial for understanding how these systems will respond to the warmer and drier conditions predicted as a result of global climate change.

}, keywords = {decades, ex-urban, transportation activity}, author = {Danielle Duni and Jeffrey E. Herrick} } @conference {50324, title = {The functional role of carbonate-cemented soil horizons in desert ecosystems: Spatial and temporal dynamics of plant water availability}, booktitle = {Ecological Society of America }, year = {2007}, month = {August 5-10, 200}, pages = {COS 147-6}, address = {San Jose, CA}, abstract = {In water limited ecosystems, soil profile characteristics can control plant community composition and production through their effects on spatial and temporal patterns of plant available water. Little is known, however, about water availability in soil horizons cemented with carbonates (petrocalcic horizons), which occur extensively in arid ecosystems. To investigate petrocalcic water retention and dynamics, a series of replicated experiments at multiple spatial scales was conducted in a mixed shrub-grass community in southern New Mexico, USA. A laboratory study was conducted evaluating the water holding capacity of a variety of petrocalcic material. Petrocalcic temporal water availability and dynamics were monitored in two multiyear field studies: a pasture scale study comparing water availability across soils with differing degrees of petrocalcic development and a companion patch-interspace scale study investigating soil-water dynamics associated with woody shrub encroachment in a petrocalcic soil. Petrocalcic available water holding capacities were up to four times those of the sandy loam parent material. Calcic and petrocalcic horizons retained much greater amounts of available soil water for several months following above-normal winter and summer precipitation than similar depths in a non-carbonate sand. The companion study in the petrocalcic soil showed that unvegetated interspaces absorbed significantly more soil water during a wet winter and retained more available soil water into the spring than soils under shrubs. Wetting and drying dynamics indicate petrocalcic horizons release stored water into the grass rooting zone. Furthermore, patterns of water availability suggest soils with shallow petrocalcic horizons are beneficial to the establishment and persistence of grasses.}, keywords = {carbonate-cemented, spatial, temporal}, author = {Danielle Duni and Jeffrey E. Herrick and Curtis H. Monger} } @article {50325, title = {The high water-holding capacity of petrocalcic horizons}, journal = {Soil Science Society of America}, volume = {71}, number = {3}, year = {2007}, month = {05/2007}, pages = {812-819}, abstract = {

Petrocalcic soil horizons occur in most arid and semi-arid ecosystems around the world, often within the plant rooting zone. Little is known, however, about the water holding characteristic of soils indurated with calcium carbonate. We conducted a replicated experiment to define the soil-water release curve (SWRC) for a range of petrocalcic horizon materials. Samples from both plugged and laminar zones of two stage V petrocalcic horizons in southern New Mexico were characterized. Wetter soil-water potentials were measured using a pressure plate; more negative potentials (down to \<{\textendash}10 MPa) were measured using a chilled mirror water activity meter. Measured SWRC data were fitted to the Van Genuchten equation. The SWRC methods used were found to be both reliable and repeatable. Plant available water holding capacity (AWHC) for desert species (with wilting point set at {\textendash}4.0 MPa)ranged from 0.26 m3 m-3 in plugged zones to 0.06 m3 m-3 in some laminar zones in contrast to ~ 0.07 m3 m-3 in the loamy sand parent material. Correlation analyses across morphologies of AWHC and soil properties resulted in significant statistical relationships only with bulk density and porosity. AWHC and calcium carbonate content, however, were significantly negatively correlated within the laminar and positively correlated within the plugged petrocalcic horizon morphologies. Cementation by calcium carbonate dramatically alters the water holding characteristics of soils and understanding these horizons is crucial to understand patterns of soil-water in desert systems throughout the world.

}, keywords = {Petrocalcic, soil}, url = {/files/bibliography/07-014.pdf}, author = {Danielle Duni and Jeffrey E. Herrick and Curtis H. Monger} } @conference {50437, title = {The importance of soil carbonates for available water holding capacity in arid ecosystems of the Americas}, booktitle = {Ecology International Congress}, year = {2006}, month = {January 10, 2006}, pages = {Paper No. 59106}, address = {Merida, Mexico}, abstract = {Petrocalcic and calcic soil horizons develop extensively in arid and semi-arid ecosystems across more than 15\% of the Americas. Many of these horizons occur within the rooting zone of grasses and row crops and all are within the rooting depths of deep rooted desert shrubs. The accumulation of calcium carbonate in coarse textured soils can produce a dramatic change in water holding capacity through the conversion of a soil horizon dominated by large pores to a fine pore matrix. Understanding soil available water holding capacity (AWHC) is important for both forage and row crop production systems. Soil AWHC can control production and plant community composition by affecting the spatial and temporal patterns of plant available water. We conducted laboratory experiments and field surveys assessing the importance of carbonate accumulation for soil profile AWHC and the temporal availability of plant available water in high carbonate soils in southern New Mexico, USA. The added water holding capacity due to carbonates more than doubled the AWHC of some coarse textured soils but was less important in fine textured soils. Many high carbonate soil horizons, even horizons cemented with calcium carbonate, received substantial increases in soil water content during periods of winter recharge. Petrocalcic and partially indurated calcic horizons are often overlooked when assessing soil profile available water. This study indicates that petrocalcic and calcic horizons can contain significant amounts of plant available water and are important when assessing soil available water holding capacity.}, keywords = {calcic, Petrocalcic, semi-arid}, author = {Danielle Duni and Jeffrey E. Herrick and Curtis H. Monger} } @conference {50647, title = {The high water-holding capacity of petrocalcic horizons}, booktitle = {Soil Science Society of America Annual Meeting}, year = {2004}, month = {October 31-Novem}, address = {Seattle, WA}, abstract = {Petrocalcic soil horizons develop extensively in arid ecosystems around the world, often within the rooting zone of many desert plant species. In coarse textured soils, this results in a dramatic change in moisture holding capacity through the conversion of a horizon dominated by large pores to a fine pore matrix. We conducted a replicated experiment to measure the characteristic moisture release curve for a range of petrocalcic horizon materials. Samples from both the plugged and laminar horizons from two stage V petrocalcic horizons in southern New Mexico were sampled. Tensions closer to zero were measured using a pressure plate; more negative tensions (down to {\textendash}5Mpa) were measured using a chilled mirror water potential device (Decagon Devices WP4). Our method was repeatable and results were fitted using the vanGenuchten equation. Plant available volumetric water holding capacity for desert species (with permanent wilting point set at {\textendash}4Mpa) ranged from 24\% in plugged horizons to 3\% in some laminar horizons in contrast to approximately 5.5\% in a loamy sand. Cementation by calcium carbonate dramatically alters the water-holding characteristics of soils and understanding these horizons is crucial for understanding patterns of soil water in desert systems.}, keywords = {arid, ecosystems, horizons, Petrocalcic, soil, soil water, water-holding capacity}, author = {Danielle Duni and Jeffrey E. Herrick and Curtis H. Monger and Brinegar, H.R.} }