@proceedings {JRN55419, title = {The economic costs of wind erosion in the United States}, year = {2022}, month = {12-9 to14-2022}, address = {Chicago, IL}, abstract = {Wind erosion negatively impacts many aspects of society, but its socioeconomic costs in the United States were last assessed comprehensively during the 1990s. It has been over three decades since and both the climate and society have changed greatly. Solar panel and wind turbine usage have risen drastically, and an infectious disease known as Valley fever that is linked to soil (and thus likely dust) has been growing in incidence. Windblown dust has also caused an increase in transportation fatalities. Due to these and other changes, we decided to re-assess the previous estimate of $10 billion annual cost of wind erosion from Pimentel et al. (1995). We examined existing literature on past cost estimates and used domestic research data when possible. Some cost estimates, such as dust morbidity, were directly taken from past studies and adjusted for inflation if necessary. Other estimates, such as loss estimates from renewable energy generation, Valley fever, and transportation costs were built from the ground up. Values for energy generation, Valley fever cases, and transportation costs were drawn from their respective government sources, such as the Department of Energy, the Centers for Disease Control and Prevention, and the Department of Transportation. The data were then modified by findings from other studies (i.e. percentage of loss attributed to dust), enabling total costs to be calculated with the cost per increment, such as the cost of one KWh of wind energy or the cost per motor vehicle crash. We found that with the most conservative parameters, windblown dust cost the U.S. at least $69 billion in the year 2017. This $69 billion estimate is likely an underestimate as other factors were not accounted for, such as airport delays and increased desertification. This study serves as an updated baseline estimate for the cost of wind erosion, but further detailed research needs to be conducted to create a more complete cost estimate for the United States. }, keywords = {economic costs, renewable energy, society, solar panel, turbine, valley fever, wind erosion}, author = {Irene Feng and Daniel Tong and Thomas E. Gill and Scott Van Pelt and Nicholas Webb} } @article {JRN55341, title = {Parameterizing an aeolian erosion (AERO) model for rangelands}, journal = {Aeolian Research}, volume = {54}, year = {2021}, month = {12/13/2021}, chapter = {100769}, abstract = {Aeolian processes are fundamental to arid and semi-arid ecosystems, but modeling approaches are poorly developed for assessing impacts of management and environmental change on sediment transport rates over meaningful spatial and temporal scales. For model estimates to provide value, estimates of sediment flux that encapsulate intra- and inter-annual and spatial variability are needed. Further, it is important to quantify and communicate transparent estimates of model uncertainty to users. Here, we present a wind erosion and dust emission model parameterized for rangelands using a Generalized Likelihood Uncertainty Estimation framework. Modeled horizontal sediment flux was calibrated using data from five diverse grassland and shrubland sites from the USDA National Wind Erosion Research Network. Observations of wind speed, vegetation height, length of gaps between vegetation, and percent bare ground were used as model inputs. Horizontal sediment flux estimates from 10,000 independently selected parameter sets were compared to flux observations from 44 \~{} month-long collection periods to calculate a likelihood measure for each model. Results show good agreement for individual sampling periods across sites with few observations falling outside prediction bounds and a one-to-one relationship between median predictions and observations. Additionally, combined distributions of sediment flux estimates from all sample periods for a given site closely approximated the probability of observing a given flux at that site. These results suggest AERO effectively represents temporal variability in aeolian transport rates at rangeland sites and provides robust assessments suitable for assessing land health and better predicting changes in air quality and the impacts of land management activities.}, keywords = {aeolian, assessment, dust emission, indicators, land management, monitoring, wind erosion}, doi = {10.1016/j.aeolia.2021.100769}, url = {files/bibliography/21-052.pdf}, author = {Brandon Edwards and Nicholas Webb and Magda Galloza and Justin Van Zee and Ericha Courtright and Brad Cooper and Loretta Metz and Jeffrey E. Herrick and Gregory S. Okin and Danielle Duni and John Tatarko and Negussie Tedela and Daniel N. Moriasi and Beth Newingham and Frederick B. Pierson and David P. Toledo and Scott Van Pelt} } @article {JRN55348, title = {Wind erosion response to past and future agro-pastoral trajectories in the Sahel (Niger)}, journal = {Landscape Ecology}, year = {2021}, month = {11/09/2021}, abstract = {Context Wind erosion plays a major role in land degradation in semi-arid areas, especially in the Sahel. There, wind erosion is as sensitive to land use and land management as to climate factors. Future land use intensification may increase wind erosion and induce regional land degradation. Objective We aimed to estimate wind erosion responses to changing land management in a Sahelian region. Methods We defined land use intensification scenarios for a study site in southwestern Niger for two historical situations (1950s and 1990s), and two alternative prospective scenarios (2030s: extensive or intensive). We simulated vegetation growth and horizontal sediment flux of wind erosion for the corresponding landscapes. Results Annual amounts of horizontal sediment flux increased with land management changes from 1950s (nil flux) to 1990s (176 kg m-1 yr-1) and 2030s (452 to 520 kg m-1 yr-1), mostly because of differences in land use, declining soil fertility, and practices decreasing the dry vegetation. For 2030s, intensive scenario exhibited larger vegetation yields than extensive conditions, but similar large values of horizontal sediment flux, thus questioning the sustainability of both scenarios. Realistic sets of practices had as large an influence as the largest theoretical range of practices on the variability of annual horizontal sediment flux. This variability was as large as that due to meteorological conditions. Conclusions This study demonstrates that the environmental impact of land use and management practices, of which wind erosion is an aspect, must be assessed at the landscape scale to account for the variability in land cover and associated land management.}, keywords = {Agro-pastoral practices, Land management scenarios, land use, modelling, Sahel, wind erosion}, doi = {10.1007/s10980-021-01359-8}, url = {files/bibliography/21-057.pdf}, author = {C. Pierre and P. Hiernaux and Jean-Louis Rajot and L. Kergoat and Nicholas Webb and A. Abdourhamane Tour{\'e} and B{\'e}atrice Marticorena and C. Bouet} } @article {JRN55272, title = {Vegetation Canopy Gap Size and Height: Critical Indicators for Wind Erosion Monitoring and Management}, journal = {Rangeland Ecology \& Management}, volume = {76}, year = {2021}, month = {May 2021}, pages = {78-83}, abstract = {Indicators of vegetation cover and structure are widely available for monitoring and managing rangeland wind erosion. Identifying which indicators are most appropriate for managers could improve wind erosion mitigation and restoration efforts. Vegetation cover directly protects the soil surface from erosive winds and reduces wind erosivity by extracting momentum from the air. The portion of the soil surface that is directly protected by vegetation is adequately described by fractional ground cover indicators. However, the aerodynamic sheltering effects of vegetation, which are more important for wind erosion than for water erosion, are not captured by these indicators. As wind erosion is a lateral process, the vertical structure and spatial distribution of vegetation are most important for controlling where, when, and how much wind erosion occurs on rangelands. These controlling factors can be described by indicators of the vegetation canopy gap size distribution and vegetation height, for which data are collected widely in the United States by standardized rangeland monitoring and assessment programs. In this paper we address why canopy gap size distribution and vegetation height are critical indicators of rangeland wind erosion and health. We review wind erosion processes to explain the physical role of these vegetation attributes. We then address the management implications including availability of data on the indicators on rangelands and needs to make the indicators and model estimates of wind erosion more accessible to the range management community.}, keywords = {canopy, dust monitoring, gap size, rangeland health, Vegetation height, wind erosion}, doi = {doi.org/10.1016/j.rama.2021.02.003}, url = {files/bibliography/21-007.pdf}, author = {Nicholas Webb and Sarah McCord and Brandon Edwards and Jeffrey E. Herrick and Emily Kachergis and Gregory S. Okin and Justin Van Zee} } @article {JRN55157, title = {Comparison of soil-aggregate crushing-energy meters}, journal = {Aeolian Research}, volume = {42}, year = {2020}, month = {01/10/2020}, abstract = {

Dry aggregate stability (DAS) is an important factor influencing soil wind erosion, dust emission and crop production. Historically and to the present, DAS has been determined using a horizontal- or vertical-plate crushing meter (Soil-Aggregate Crushing-Energy Meter, hereafter SACEM). The intent of this paper was to compare the performance of horizontal-plate SACEM with a commercial penetrometer (Mohr Digi-Test, hereafter MDT). The performance of both instruments was tested on aggregates collected from various soil types, crop rotations, soil amendments, and tillage systems across the inland Pacific Northwest United States (iPNW). Results indicated no consistently significant difference in DAS measured by the MDT and SACEM. However, there was evidence that SACEM under-estimated or MDT over-estimated DAS by 74 to 368\% in measuring the stability of strong aggregates (DAS \> 3 J kg-1). Both instruments measured higher DAS for no-tillage summer fallow, winter wheat-summer fallow (WW-SF) rotations, and no green manure treatments compared with other tillage practices, oilseed rotations, and green manure treatments. The SACEM that has historically been used in measuring soil DAS can be replaced by the commercial penetrometer (MDT). Nonetheless, differences in the performance of instruments in measuring the stability of strong aggregates poses risks.

}, keywords = {Abrasion, Binding energy, Dry aggregate stability, dust emission, Particle cohesion, wind erosion}, doi = {10.1016/j.aeolia.2019.100559}, url = {files/bibliography/20-002.pdf}, author = {H. Pi and David Huggins and Nicholas Webb and Brenton Sharrat} } @proceedings {JRN55189, title = {Defining thresholds for wind erosion in desert rangeland STMs}, volume = {Session 9}, year = {2020}, month = {02/16/2020}, address = {Denver, CO}, abstract = {

Within the US, conventional understanding has been that most erosion is occurring in the Great Plains, but our knowledge about the extent and severity of rangeland wind erosion has been limited by monitoring and modeling technologies. Data from air quality monitoring programs like IMPROVE show there was a 75\% increase in spingtime fine dust concentrations between 2000 and 2014 across the western states, but we still have a limited understanding of where, when and how much erosion is occurring. Importantly, few tools are available to help managers assess why wind erosion is occurring in responses to land use and management. This information is needed to identify appropriate conservation practices. As a consequence, wind erosion isn{\textquoteright}t typically considered in assessments of land resource condition despite its importance for plant community dynamics, agroecosystem resilience, regional air quality and climate. To address this problem we developed an Aeolian EROsion (AERO) model designed to run on standardized soil and vegetation monitoring datasets that are collected across the west. AERO is a physically-based model that requires inputs of surface soil texture, bare soil fraction, canopy gap size distribution, average canopy height and time-series or probability distribution of wind speeds for a plot location. By leveraging large standardized monitoring datasets, like those collected by the NRCS NRI and BLM AIM programs, AERO can be used to develop an understanding of potential sediment transport rates and dust emissions across rangelands as influenced by soil properties and the kinds, amounts, proportions and structure of different vegetation species. From AERO applications, we are developing approaches based on the Ecological Land Resource Hierarchy to understand the range of potential wind erosion for different land units at different spatial scales. Our work is then exploring approaches to establish benchmarks based on structural and functional thresholds of concern that enable managers to evaluate how wind erosion responds to changes in the kinds, amounts and proportions of vegetation within ecological sites. By using AERO to integrate the indicators of vegetation structure, the model can also be used to identify functional thresholds for wind erosion and assess whether these thresholds can be generalized across ecological sites and states to inform management at broader spatial scales.

}, keywords = {desert rangeland STMs, thresholds, wind erosion}, author = {Nicholas Webb and Brandon Edwards and Rachel Burke and Sarah McCord and Justin Van Zee and Ericha Courtright and Brad Cooper} } @article {JRN55165, title = {A note on the use of drag partition in aeolian transport models}, journal = {Aeolian Research}, volume = {42}, year = {2020}, month = {01/01/2020}, abstract = {

Sediment transport equations used in wind erosion and dust emission models generally incorporate a threshold for particle motion (u*t) with a correction function to account for roughness-induced momentum reduction and aerodynamic sheltering. The prevailing approach is to adjust u*t by the drag partition R, estimated as the ratio of the bare soil threshold (u*ts) to that of the surface in the presence of roughness elements (u*tR). Here, we show that application of R to adjust only the entrainment threshold (u*t = u*ts/R) is physically inconsistent with the effect of roughness on the momentum partition as represented in models and produces overestimates of the sediment flux density (Q). Equations for Q typically include a wind friction velocity scaling term (u*n). As Q scales with wind friction velocity at the soil surface (uS*), rather than total wind friction velocity uT* (implicitly u* in models), u*n must be also adjusted for roughness effects. We further note that the practice of reducing Q by the vegetation cover fraction to account for the physically-protected surface area constitutes double accounting of the surface protection when R is represented through the basal-to-frontal area ratio of roughness elements (s) and roughness density (\&$\#$39;). If the drag partition is implemented fully, additional tuning for surface protection is unnecessary to produce more accurate aeolian transport estimates. These findings apply equally to models of the vertical dust flux.

}, keywords = {Aeolian threshold, dust emission, friction velocity, roughness, Shear stress partitioning, wind erosion}, doi = {10.1016/j.aeolia.2019.100560}, url = {files/bibliography/20-003.pdf}, author = {Nicholas Webb and A. Chappell and Susan LeGrand and N. Ziegler and Brandon Edwards} } @article {JRN55068, title = {Soil Organic Carbon Erosion is Critical for Land Degradation Neutrality}, journal = {Environmental Science and Policy}, volume = {93}, year = {2019}, month = {03/2019}, pages = {43-52}, chapter = {43}, abstract = {

The Land Degradation-Neutrality (LDN) framework of the United Nations Convention to Combat Desertification (UNCCD) is underpinned by three complementary interactive indicators (metrics: vegetation cover, net primary productivity; NPP and soil organic carbon; SOC) as proxies for change in the land-based natural capital. The LDN framework assumes that SOC changes slowly primarily by decomposition and respiration of CO2 to the atmosphere. However, we show there is growing evidence that SOC erosion also reduces SOC stocks and rapidly after land use / cover change. Here we use a physically-based model to quantify global SOC erosion by wind (2001-2010) and identify global dryland regions where SOC erosion may be a significant problem for achieving LDN. Selected sites in global drylands show SOC erosion accelerating over time. Without targeting and reducing SOC erosion, management practices will fail to sequester SOC and reduce land degradation, thereby undermining the LDN framework. We describe the interrelated nature of the LDN indicators, the importance of including SOC erosion and how land cover can be replaced by erosion that better represents the physical effects of land cover on land degradation processes. Therefore, we call for SOC erosion to become an LDN indicator. Furthermore, our results suggest that fluxes of SOC and soil nutrients by soil erosion should be emphasised in the forthcoming Intergovernmental Panel on Climate Change (IPCC) Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.

}, keywords = {land cover, land degradation neutrality, sequestration, soil organic carbon, wind erosion}, doi = {doi.org/10.1016/j.envsci.2018.12.020}, url = {files/bibliography/19-009.pdf}, author = {A. Chappell and Nicholas Webb and John Leys and Waters, Cathy and Orgill, Susan and Eyres, Michael} } @article {JRN55137, title = {Climate change impacts on wind and water erosion on US rangelands}, journal = {Journal of Soil and Water Conservation}, volume = {74}, year = {2019}, month = {07/2019}, pages = {405-418}, chapter = {405}, abstract = {

Soil erosion by water and wind in US rangelands has serious implications for rangeland health, food security, and poses significant hazards to human health and communities. Accordingly, understanding how future climate change may impact soil erosion is critical for developing appropriate management strategies that mitigate negative impacts to the extent practical and potentially build resilience. Here, we review potential impacts of climate change on controls of erosion in US rangelands and discuss potential erosion responses. Projected climate changes are expected to have regionally variable effects on important controls of erosion, especially vegetation cover; community composition; frequency, magnitude, and geographical range of fire disturbance; and high intensity, erosive weather events, all of which have the potential to increase rangeland vulnerability to erosion. We identify knowledge gaps relevant to these controls and discuss management considerations to address climate change impacts to soil erosion concerns for US rangelands. We recommend using existing monitoring data to create assessments of vulnerability, that soil erosion should be explicitly included in management benchmarks and decision support tools, and that no-regrets management options be implemented in anticipation of future impacts, which can improve resilience and the efficacy of climate change adaptation.

}, keywords = {climate change, rangeland, soil erosion, water erosion, wind erosion}, doi = {doi.org/10.2489/jswc.74.4.405}, url = {files/bibliography/19-017.pdf}, author = {Brandon Edwards and Nicholas Webb and David A. Brown and Emile H. Elias and Dannele E. Peck and Frederick B. Pierson and Jason C. Williams and Jeffrey E. Herrick} } @article {JRN55042, title = {The interactive role of wind and water in functioning of drylands: what does the future hold?}, journal = {BioScience}, volume = {68}, year = {2018}, month = {09/2018}, pages = {670-677}, chapter = {670}, abstract = {

Feedback mechanisms between abiotic and biotic processes in dryland ecosystems lead to a strong sensitivity to interannual variations in climate. Under a future regime of higher temperatures but potentially increased rainfall variability, drylands are anticipated to experience changes in wind and water transport that will alter plant community composition and feedback on landscape connectivity. Here, we present a conceptual framework for understanding the coupling of vegetation productivity, aeolian transport, and hydrologic connectivity under anticipated changes in future climate, which suggests that a more extreme climatic regime will lead to more connected landscapes with attendant losses in soil, nutrient, and water resources. When enhanced connectivity triggers state changes, irreversible changes in ecosystem functioning can occur, with implications for the future of global drylands.

}, keywords = {aeolian, connectivity, deserts, precipitation, runoff, wind erosion}, doi = {10.1093/biosci/biy067 }, url = {files/bibliography/JRN55042.pdf}, author = {Gregory S. Okin and O. E. Sala and Enrique Vivoni and J. Zhang and Abinash Bhattachan} } @article {JRN54575, title = {The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management}, journal = {Aeolian Research}, volume = {22}, year = {2016}, month = {05/2016}, pages = {23-36}, chapter = {23}, abstract = {

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture{\textquoteright}s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: 1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, 2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and 3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties which influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

}, keywords = {aeolian, dust emission, Long-Term Agroecosystem Research, monitoring, Network, wind erosion}, doi = {10.1016/j.aeolia.2016.05.005}, url = {/files/bibliography/16-010.pdf}, author = {Nicholas Webb and Jeffrey E. Herrick and Justin Van Zee and Ericha Courtright and Hugenholtz, Christopher and Teddy M. Zobeck and Gregory S. Okin and Barchyn, Thomas and Billings, Benjamin and Boyd, Robert and Clingan, Scott and Brad Cooper and Danielle Duni and J. D. Derner and Fox, Fred A. and Kris Havstad and Phil Heilman and Valerie LaPlante and Ludwig, Noel and Loretta Metz and Mark A. Nearing and Norfleet, M.L. and Frederick B. Pierson and Matt A Sanderson and Brenton Sharrat and Jean Steiner and John Tatarko and Negussie Tedela and David P. Toledo and Unnasch, Robert S. and Scott Van Pelt and Wagner, Larry E.} } @article {JRN54495, title = {Threshold wind velocity dynamics as a driver of aeolian sediment mass flux}, journal = {Aeolian Research}, volume = {20}, year = {2016}, month = {03/2016}, pages = {45-59}, chapter = {45}, abstract = {

Horizontal (saltation) mass flux is a key driver of aeolian dust emission. Estimates of the horizontal mass flux underpin assessments of the global dust budget and influence our understanding of the dust cycle and its interactions. Current equations for predicting horizontal mass flux are based on limited field data and are constrained to representing transport-limited equilibrium saltation, driven by the wind momentum flux in excess of an entrainment threshold. This can result in large overestimation of the sediment mass flux. Here we compare measurements of the soil entrainment threshold, horizontal mass flux, and their temporal variability for five undisturbed dryland soils to explore the role of threshold in controlling the magnitude of the mass flux. Average and median entrainment threshold showed relatively small variability among sites and relatively small variability between seasons, despite significant differences in soil surface conditions. Physical and biological soil crusts had little effect on the threshold value, and threshold appeared to play a minor role in determining the magnitude of the mass flux. Our results suggest that horizontal mass flux was controlled more by the supply limitation and abrasion efficiency of saltators present as loose erodible material or originating from neighboring soil sources. The omission of sediment supply and explicit representation of saltation bombardment from horizontal flux equations is inconsistent with the process representation in dust emission schemes and contributes to uncertainty in model predictions. This uncertainty can be reduced by developing greater process fidelity in models to predict horizontal mass flux under both supply- and transport-limited conditions.

}, keywords = {dust, erodibility, supply limitation, transport sediment flux, wind erosion}, doi = {10.1016/j.aeolia.2015.11.006}, url = {/files/bibliography/16-002.pdf}, author = {Nicholas Webb and Magda Galloza and Teddy M. Zobeck and Jeffrey E. Herrick} } @article {JRN52687, title = {Soil organic carbon enrichment of dust emissions: Magnitude, mechanisms and its implications for the carbon cycle}, year = {2013}, abstract = {

Soil erosion is an important component of the global carbon cycle. However, little attention has been given to the role of aeolian processes in influencing soil organic carbon (SOC) flux and the release of greenhouse gasses, such as carbon-dioxide (CO2), to the atmosphere.\  Understanding the magnitude and mechanisms of SOC enrichment in dust emissions is necessary to evaluate the impact of wind erosion on the carbon cycle. This research examines the SOC content and enrichment of dust emissions measured using Big Spring Number Eight (BSNE) wind-vane samplers across five land types in the rangelands of western Queensland, Australia. Our results show that sandy soils and finer particulate quartz-rich soils are more efficient at SOC emission and have larger SOC dust enrichment than clay-rich aggregated soils. The SOC enrichment ratios of dusts originating from sites with sand-rich soil ranged from 2.1-41.9, while the mean enrichment ratio for dusts originating from the clay soil was 2.1. We hypothesise that stronger inter-particle bonds and the low grain density of the aggregated clay soil explain its reduced capacity to release SOC during saltation, relative to the particulate sandy soils. We also show that size-selective sorting of SOC during transport may lead to further enrichment of SOC dust emissions. Two dust samples from regional transport events were found to contain 15-20\% SOC. These preliminary results provide impetus for additional research into dust SOC enrichment processes to elucidate the impact of wind erosion on SOC flux and reduce uncertainty about the role of soil erosion in the global carbon cycle.

}, keywords = {aeolian dust, carbon cycle, rangelands, soil nutrients, wind erosion}, doi = {10.1002/esp.3404}, url = {/files/bibliography/13-032.pdf}, author = {Nicholas Webb and Craig Strong and A. Chappell and Samuel K. Marx and Grant McTainish} } @proceedings {JRN54540, title = {The impacts of grazing land management on the wind erodibility of the Mulga Lands of western Queensland, Australia}, volume = {p. 60}, year = {2012}, month = {09/2012}, publisher = {Australian Rangeland Society}, address = {Kununurra, Western Australia}, abstract = {An estimated 100 Mt of dust is eroded by wind from the Australian land surface each year. Wind erosion may be widespread across the arid and semi-arid rangelands, with impacts on soil nutrients, carbon and ecosystem services, human health, and climate. The susceptibility of landscapes to wind erosion (their erodibility) is highly sensitive to changes in vegetation cover and soil properties like crusting and aggregation, which control the area of bare ground exposed to erosive winds, and the availability of fine erodible sediment. Pastoralism, including the production of cattle and sheep, is thought to modify these controls through its impacts on vegetation cover and soil surface properties. However, research is yet to quantify the impact of grazing land management on the erodibility of rangelands, or how these impacts vary between land types. We present a simulation analysis that implements the Australian Land Erodibility Model (AUSLEM) in line with a pasture growth and animal production model (GRASP) to evaluate the impacts of grazing management on the erodibility of 5 land types in western Queensland. The study has tested separately the effects of stocking rates, stocking strategies and land condition on wind erodibility. Our results show that wind erodibility increases with stocking rate, showing a nonlinear response that varies in intensity between land types. Susceptibility of the land types to wind erosion is shown to increase under stocking strategies that lack flexibility or the capacity to rapidly destock in response to drought conditions. However, moving from high stocking rates under a fixed stocking to a more flexible strategy is shown to have a greater effect on erodibility than differences between flexible stocking strategies based around the long term safe stocking rates. The degradation of land condition results in an increase of wind erodibility with an abrupt change of rates representing major shifts in environmental conditions. The analysis indicates that historical stocking rates have had a high impact on wind erodibility; however, under the current stocking rate, impacts on wind erodibility are reduced. Wind erodibility can be reduced by adopting a conservative management with low stocking rates as well as maintaining the land in good condition.}, keywords = {GRASP, land degradation, management, modelling, stocking rate, wind erosion}, author = {Aubault, Helene and Nicholas Webb and Scanlan, Joe C. and Craig Strong and John Leys} } @article {49924, title = {Dust emissions from undisturbed and disturbed, crusted playa surfaces: cattle trampling effects}, journal = {Aeolian Research}, volume = {3}, year = {2011}, month = {05/2011}, pages = {31-41}, chapter = {31}, abstract = { Dry playa lake beds can be significant sources of fine dust emission. This study used a portable field wind tunnel to quantify the PM10 emissions from a bare, fine-textured playa surface located in the far northern Chihuahua Desert. The natural, undisturbed crust and its subjection to two levels of animal disturbance (one and ten cow passes) were tested. The wind tunnel generated dust emissions under controlled conditions for firstly an initial blow-off of the surface, followed by two longer runs with sand added to the flow as an abrader material. Dust was measured using a GRIMM particle monitor. For the study playa, no significant differences in PM10 concentration and emission flux were found between the untrampled surface and following a single animal pass. This was the case for both the initial blow-offs and tests on plots under a steady abrader rate. Significantly higher dust loading was only associated with the effect of 10 animal passes. In the blow-offs, the higer PM10 yield after 10 passes reflected the greater availability of easily entrainable fine particles. Under abrasion, the effect of the heaviest trampling increased the emission flux by a third and abrasion efficiency by around 50\% more than values on the untrampled surface. This enhanced abrasion efficiency peristed for a 30 minute period under abrasion before the positive effect of the disturbance was no longer evident. The findings highlight the role of a threshold of disturbance that determines if supply-limited surfaces will exhibit enhanced wind erosion or not after undergoing perturbation.}, keywords = {anthropogenic dust, mineral aerosols, playas, wind erosion, wind tunnel}, doi = {10.1016/j.aeolia.2011.03.007}, url = {/files/bibliography/11-008.pdf}, author = {Matthew C. Baddock and Teddy M. Zobeck and Scott Van Pelt and E.L. Fredrickson} } @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 {49965, title = {Responses of wind erosion to climate-induced vegetation changes on the Colorado Plateau}, journal = {Proceedings of the National Academy of Sciences}, volume = {108}, year = {2011}, pages = {3854-3859}, abstract = {

Projected increases in aridity throughout the southwestern United States due to anthropogenic climate change will likely cause reductions in perennial vegetation cover, which leaves soil surfaces exposed to erosion. Accelerated rates of dust emission from wind erosion have large implications for ecosystems and human wellbeing, yet there is poor understanding of the sources and magnitude of dust emission in a hotter and drier climate. Here we use a two-stage approach to compare the susceptibility of grasslands and three different shrublands to wind erosion on the Colorado Plateau and demonstrate how climate can indirectly moderate the magnitude of aeolian sediment flux through different responses of dominant plants in these communities. First, using results from 20 y of vegetation monitoring, we found perennial grass cover in grasslands declined with increasing mean annual temperature in the previous year, whereas shrub cover in shrublands either showed no change or declined as temperature increased, depending on the species. Second, we used these vegetation monitoring results and measurements of soil stability as inputs into a field-validated wind erosion model and found that declines in perennial vegetation cover coupled with disturbance to biological soil crust resulted in an exponential increase in modeled aeolian sediment flux. Thus the effects of increased temperature on perennial plant cover and the correlation of declining plant cover with increased aeolian flux strongly suggest that sustained drought conditions across the southwest will accelerate the likelihood of dust production in the future on disturbed soil surfaces.

}, keywords = {arid, climate change, Colorado Plateau, horizontal flux, land use, national park, threshold shear velocity, vegetation change, wind erosion}, doi = {10.1073/pnas.1014947108}, url = {files/bibliography/JRN00582.pdf}, author = {Seth M. Munson and Jayne Belnap and Gregory S. Okin} } @article {50116, title = {Effects of enhanced wind erosion on surface soil texture and characteristics of windblown sediments}, journal = {Journal of Geophysical Research - Biogeosciences}, volume = {114, G02003}, year = {2009}, chapter = {8 pp}, abstract = {

It is well documented that wind redistributes and transports soil resources in semiarid ecosystems. However, fewer studies have quantitatively linked wind erosion to detailed grain-size fractions and associated nutrient content in surface soil and windblown sediment. In this study, we examined (1) the effects of enhanced wind erosion on surface soil particle-size distribution and (2) carbon (C) and nitrogen (N) characteristics of windblown sediments in a typical desert grassland of southern New Mexico. Our results show that surface soil has become noticeably coarser over a 2-year period. In particular, content of soil particles in the category of 250{\textendash}500 ?m increased significantly, but soil particles in the fractions of 50{\textendash}125 {\textmu}m and \<50 {\textmu}m were significantly depleted. In addition to the enrichment of C and N in the windblown sediments, our results reveal that fine particles (e.g., D \< 50 {\textmu}m) were enriched to a much higher degree at height than C and N. Significantly, our results reveal that nearly 12\% of total organic carbon (TOC) and 9\% of total nitrogen (TN) were found in the particles with diameter \<50 {\textmu}m, which account for only 1{\textendash}2\% of the mass of windblown sediments. In this wind susceptible environment, our findings suggest that (1) significant soil texture change (e.g., the loss of soil fines) driven by wind erosion could happen rapidly and soil fine particles (e.g., silt and clay) may be depleted within a few years and (2) the loss of even a small fraction of fine particles may indicate a substantial depletion of soil C and N.

}, keywords = {aeolian processes, surface soil texture, wind erosion, windblown sediment}, doi = {10.1029/2008JG000903}, url = {files/bibliography/JRN00526.pdf}, author = {Junran Li and Gregory S. Okin and Howard Epstein} } @article {50356, title = {Quantitative effects of vegetation cover on wind erosion and soil nutrient loss in a desert grassland of southern New Mexico, USA}, journal = {Biogeochemistry}, volume = {85}, year = {2007}, note = {//USDA//LTER-V//entered 08/14/2007}, month = {2007}, pages = {317-332}, abstract = {

Wind is a key abiotic factor that influences the dynamics of arid and semiarid systems. We investigated two basic relationships on vegetation manipulation (grass cover reduction) plots at the Jornada Experimental Range in southern New Mexico: (1) wind erosion rates (horizontal mass flux and dust emission) versus vegetative cover, and (2) nutrient loss versus vegetative cover. The results indicate that wind erosion rates and nutrient loss by dust emission are strongly affected by plant cover; however, the importance of shrubs and grasses in reducing dust flux may not be equal. The dramatic increase of wind erosion between 75\% grass cover reduction and 100\% grass cover reduction suggests that sparsely distributed mesquites are relatively ineffective at reducing wind erosion and nutrient loss compared to grasses. Comparisons of nutrients between surface soils and wind blown dust indicate that aeolian transport is a major cause for the loss of soil nutrients in susceptible environments. We found that increased aeolian flux over three windy seasons (March 2004{\textendash}July 2006) removed up to 25\% of total organic carbon (TOC) and total nitrogen (TN) from the top 5 cm of soil, and about 60\% of TOC and TN loss occurred in the first windy season (March{\textendash}July 2004). The balance between net loss of nutrients by aeolian processes and the addition of nutrients by biotic processes changed from negative (net loss) to positive (net accumulation) between 50\% grass cover reduction and 25\% grass cover reduction. The estimated lifetime of surface soil TOC and TN of about 10 years on the plot with 100\% grass cover reduction indicates that impacts of wind erosion on soil resources can occur on very short timescales.

}, keywords = {aeolian processes, aeolian processes, desertification, article, deserts, journal, soil carbon, soil nitrogen, soil nutrients, carbon, soil nutrients, nitrogen, vegetation change, nutrient loss, vegetation change, wind erosion, vegetation cover, wind erosion, windblown sediment}, doi = {10.1007/s10533-007-9142-y}, url = {files/bibliography/JRN00480.pdf}, author = {Junran Li and Gregory S. Okin and Lorelei Alvarez and Howard Epstein} } @article {50480, title = {Multiscale controls on and consequences of aeolian processes in landscape change in arid and semi-arid environments}, journal = {Journal of Arid Environments}, volume = {65}, year = {2006}, month = {April 1, 2006}, pages = {253-275}, abstract = {Aeolian processes are tightly linked to soil and vegetation change in deserts at multiple spatial and temporal scales. Wind influences patterns of vegetation and soil within the landscape, while these patterns control wind erosion at patch to landscape scales. Aggregated at larger scales, patterns in soil and vegetation distributions influence global distributions of dust and its biogeochemical impacts. Understanding the controls on aeolian processes is, therefore, important not only in understanding the biogeochemistry and land cover patterns in dryland environments but also in understanding global land cover, climate, and biogeochemistry. These relationships are poorly understood, particularly for structurally complex plant communities such as shrub-invaded grasslands. The objective of this paper is to review the controls on aeolian processes and their consequences at plant-interspace, patch-landscape, and regional-global scales. Based on this review, we define the requirements for a cross-scale model of wind erosion in structurally complex arid and semi-arid ecosystems. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4H1004J-1-1N\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=04\%2F30\%2F2006\&_sk=999349997\&view=c\&wchp=dGLbVtb-zSkWA\&md5=e74666463d89e6fd5315d4fde2958934\&ie=/sdarticle.pdf}, keywords = {aeolian processes, desertification, dust emission, landscape change, wind erosion}, url = {/files/bibliography/06-010.pdf}, author = {Gregory S. Okin and D. E. Gillette and Jeffrey E. Herrick} } @article {50672, title = {Influence of vegetation cover and crust type on wind-blown sediment in a semi-arid climate}, journal = {Journal of Arid Environments}, volume = {58}, year = {2004}, note = {//USDA//NONE// Received and Entered 12/15/2005}, month = {2004}, pages = {167-179}, abstract = {This study determined the influence differing soil surface textures and vegetative covers haveon the magnitude of wind erosion in a semi-arid environment. The study was conducted fromMarch 2000 through late April 2000 on the Jornada Experimental Range approximately 37kmnorth of Las Cruces, New Mexico. Big Spring Number Eight (BSNE) samplers placed at ninelocations, collected particulates in suspension and saltation at heights of 5, 10, 20, 50, and100 cm from the following surfaces: loose sand, thick silty physical crust, flaky physical crust,weak desert pavement, and a forb/grass ground cover. BSNE samplers collected the largestamounts of sediment were collected in areas of loose sand and at sites directly downwind fromloose sand than sites containing heavy crusting, gravel, or a forb/grass cover. Differencesbetween sites with gravel surfaces and those with forb/grass cover were insignificant. Theseresults quantify the importance of surface cover as an agent towards reducing the extent ofwind erosion on semi-arid landscapes.{\textcopyright} 2003 Elsevier Ltd. All rights reserved.}, keywords = {aeolian processes, crust type, aeolian processes, vegetation effects, aeolian processes, wind erosion, aeolian processes, wind-transported dust, article, crusty type, journal, rangelands, saltation, vegetation cover, wind erosion}, author = {Joseph P. Hupy} } @article {50692, title = {Effects of intense, short-duration grazing on microtopography in a Chihuahuan Desert grassland}, journal = {Journal of Arid Environments}, volume = {56}, number = {3}, year = {2004}, month = {February 1, 2004}, pages = {383-393}, abstract = {

We studied the effect of three consecutive years of short duration (\<48 h per year), and intense grazing (20{\textquoteright}40 yearling cows per hectare) on soil surface microtopography in a Chihuhuan Desert grassland. We also studied the effects of shrub removal plus grazing on microtopography. Microtopography was measured in 18 plots (treatments). Treatments were a combination of two factors: (1) three levels of grazing (winter-grazed, summer-grazed, and not grazed), and (2) two levels of habitat structure (shrubs-removed and shrubs-intact). Mesquite (Prosopis glandulosa) shrubs were removed from half of the plots (nine out of 18 plots). The average height of the micromounds, the average depths of intermound depressions, and the number of micromounds were significantly reduced on the grazed plots. Shrub removal had no significant effect on the height of the micromounds or the depth of the intermound depressions of ungrazed plots. There were significant differences in average micromound heights and intermound microdepression depths attributable to the season of grazing. Microtopography was significantly reduced on grazed plots from which shrubs were removed, compared to ungrazed plots, and grazed plots with shrubs present. Grass canopy reduction, and destruction of the micromound structure in a short duration, plus intense grazing results in erosion of micromounds and in-filling of intermound depressions. The loss of microtopography coupled with reduction in vegetation height and cover resulting from short-duration intense grazing by cattle exposed soils to an increased risk of soil erosion Destruction of the micromound/microdepression topography by cattle changes the spatial patterns of water infiltration, and may homogenize nutrients in desert grasslands.

}, keywords = {cattle, grazing, Hoof-action Microtopography index, Microdepressions, Micromounds, wind erosion}, doi = {10.1016/S0140-1963(03)00062-4}, url = {/files/bibliography/04-073.pdf}, author = {M. S. Nash and E. Jackson and Walter G. Whitford} } @article {50989, title = {Particle production and aeolian transport from a "supply-limited" source area in the Chihuahuan desert, New Mexico, United States}, journal = {Journal of Geophysical Research}, volume = {106}, number = {D6}, year = {2001}, note = {//USDA//LTER IV//entered 07/16/2001;correction 08/19/2008}, month = {2001}, pages = {5267-5278}, abstract = {Wind erosion mechanisms were investigated for the "scrape site" at the Jornada Experimental Range near Las Cruces, New Mexico, in the Chihuahuan desert. The scrape site was denuded of vegetation and scraped flat in 1991. We adopted the site in 1994 because it offered an opportunity to study wind erosion mechanisms for a large area of unprotected sandy and crusted soil in an otherwise natural setting and over a period of several years. We installed and operated the following instrumentation for a period of 35 months; three meteorological towers, each 2 m in height, with wind speed sensors at 0.2, 0.5, 1.0, and 2.0 m above ground; air temperature at 0.2 and 2 m height; rain gauge; seven sets of particle collectors at 0.1, 0.5, and 1.0 m heights; and three fast-response particle mass flux sensors at 0.02, 0.1, 0.2, and 0.5 m heights; all along a transect crossing the site and parallel to the predominant southwesterly wind direction. The minimum threshold friction velocity for the scrape site with a thin layer of loose material was 25 cm s-1. This minimum threshold velocity increased to as high as 100 cm s-1 depending on the degree of particle depletion and the site{\textquoteright}s status which varied between supply unlimited just after a high wind episode and supply limited which was more typical for the rest of the time. The dominant mechanism producing fresh sediment for transport was sandblasting of the surface crust. The measurements showed that supply and availability of loose, fine particles on the surface is a strong control of rates of erosion rather than wind energy alone.}, keywords = {aeolian processes, particle production, aeolian processes, Scrape Site, aeolian processes, transport, article, articles, dust emission, journal, journals, soil erosion, wind erosion}, author = {D. E. Gillette and Chen, Weinan} } @mastersthesis {51011, title = {Aeolian particulate matter as a function of soil surface texture and vegetative cover : Jornada Basin, New Mexico}, year = {2001}, note = {//USDA//NONE// Received and Entered 12/15/2005ProCite field[12]: Not in File}, month = {2001}, pages = {70}, school = {New Mexico State University}, type = {M.S. Thesispp}, address = {Las Cruces, New Mexico}, abstract = {This study determined the influence differing soil surface textures and vegetative covers haveon the magnitude of wind erosion in a semi-arid environment. The study was conducted fromMarch 2000 through late April 2000 on the Jornada Experimental Range approximately 37kmnorth of Las Cruces, New Mexico. Big Spring Number Eight (BSNE) samplers placed at ninelocations, collected particulates in suspension and saltation at heights of 5, 10, 20, 50, and100 cm from the following surfaces: loose sand, thick silty physical crust, flaky physical crust,weak desert pavement, and a forb/grass ground cover. BSNE samplers collected the largestamounts of sediment were collected in areas of loose sand and at sites directly downwind fromloose sand than sites containing heavy crusting, gravel, or a forb/grass cover. Differencesbetween sites with gravel surfaces and those with forb/grass cover were insignificant. Theseresults quantify the importance of surface cover as an agent towards reducing the extent ofwind erosion on semi-arid landscapes. [excerpted from published work in JAE, Hupy (2004)]{\textcopyright} 2003 Elsevier Ltd. All rights reserved.}, keywords = {aeolian processes, crust type, aeolian processes, vegetation effects, aeolian processes, wind erosion, aeolian processes, wind-transported dust, crusty type, dissertation, rangelands, saltation, theses, thesis, vegetation cover, wind erosion}, author = {Joseph P. Hupy} } @article {51027, title = {Degradation of sandy arid shrubland environments: observations, process modelling, and management implications}, journal = {Journal of Arid Environments}, volume = {47}, year = {2001}, note = {//USDA//LTER IV// In file and Updated 12/15/2005}, month = {2001}, pages = {123-144}, abstract = {

Field remote sensing, and modelling observations from a degraded Mojave Desert shrubland were used to develop a model of the progressive degradation of areas adjacent to sites of direct anthropogenic disturbance. Aeolian removal and transport and dust, sand, and litter are the primary mechanisms of degradation, killing plants by burial and abrasion, interrupting natural processes of nutrient accumulation, and allowing the loss of soil resources by abiotic transport. It is concluded that any arid shrubland with wind-erodible soils is susceptible to degradation, and where possible development of these lands should be avoided.

}, keywords = {agriculture, article, articles, desertification, journal, journals, landscape, ecosystem dynamics, management, shrublands, model, process, Mojave Desert, paleolakes, shrubland, degradation, shrublands, wind erosion}, doi = {10.1006/jare.2000.0711}, url = {files/bibliography/JRN00324.pdf}, author = {Gregory S. Okin and Murray Bruce and W. H. Schlesinger} } @inbook {51026, title = {Desertification in an arid shrubland in the southwestern United States}, booktitle = {Land Degradation}, year = {2001}, note = {//NMSU,USDA//LTER IV//ProCite field[6]: In}, month = {2001}, pages = {53-70}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, address = {Dordrecht}, abstract = {

In the Mojave Desert of the southwestern U.S. human destruction of soil crusts and removal of vegetation have led to progressive, expanding degradation of adjacent arid shrublands. Aeolian mobilisation of dust, sand and litter triggered by anthropogenic disturbance contributes to the destruction of islands of fertility in adjacent areas by killing shrubs through burial and abrasion. This interrupts nutrient-accumulation processes and allows the loss of soil resources by abiotic transport. Thus the processes of degradation spread across the landscape driven largely by abiotic processes.

Soil chemical analyses and remote sensing observations presented here are designed to test a model hypothesis of degradation of arid shrublands. Nutrient and non-nutrient chemical species in the soil act as tracers of material transport and provide clues as to the nature of progressive anthropogenic degradation in arid shrublands. Remote sensing yields information about short- and long-term effects on the landscape as well as important constraints on the magnitude of degradation. Field, chemical and remote sensing observations argue for an extension of recent definitions and models of desertification to include the loss of islands of fertility in established shrublands. This extended model places arid shrublands in a continuum of physical and ecological processes and ecosystems that links semiarid grasslands with Sahara-like hyperarid barren lands.

}, keywords = {book, books, chapter, chapters, desertification, shrubland, Model Hypothesis, Mojave Desert, report, reports, Semiarid Grassland, shrubland, desertification, soil crust, wind erosion}, doi = {10.1007/978-94-017-2033-5_4}, url = {files/bibliography/JRN00325.pdf}, author = {Gregory S. Okin and Murray, B. and W. H. Schlesinger}, editor = {Conacher, A. J. ed.} } @article {51205, title = {Vulnerability of desert soil surfaces to wind erosion: the influences of crust development, soil texture, and disturbance}, journal = {Journal of Arid Environments}, volume = {39}, year = {1998}, note = {//??//LTER-III//}, month = {1998}, pages = {133-142}, keywords = {article, articles, disturbance, wind, journal, journals, soil properties, soil texture, wind erosion}, author = {Jayne Belnap and D. E. Gillette} } @article {51264, title = {Disturbance of biological soil crusts: Impacts on potential wind erodibility of sandy desert soils in southeastern Utah, U.S.A.}, journal = {Land Degradation and Rehabilitation}, year = {1997}, note = {//?//LTER III//}, month = {1997}, abstract = {

Friction threshold velocities (FTVs) were determined for biological soil crusts in different stages of recovery. Particles on the surface of crusts that had been relatively undisturbed for at least 20 years were found to have significantly higher FTVs than those that had been disturbed 5, 10 or 1 years previously (376, 87, and 46 cm sec-1, respectively). FTV{\textquoteright}s for crust breakage was also much higher for undisturbed crusts when compared to the previously disturbed crusts (573, 148, and 88 cm sec-1, respectively). All crusted surfaces were more stable than bare sand, which had an FTV of 16 cm sec-1. Disturbance treatments were then applied to the three crustal classes. Disturbance significantly reduced the FTVs of all classes by 73{\textendash}92 per cent. Comparing crustal FTVs with mean and high monthly wind speeds found in this region, it was observed that only crusts that had been undisturbed for approximately 20 years or more were able to protect soil surfaces from wind gusts expected on the average of once a month. Other crustal classes, as well as all disturbance treatments, had FTVs lower or equal to that of commonly occurring winds in this region. Because most of the crustal biomass occurs in the top 0{\textperiodcentered}3 mm of soils, even slight soil loss can negatively influence stability and nutrient inputs to this ecosystem.

}, keywords = {article, articles, cryptobiotic crust, journal, journals, soil crust, soil erosion, soil properties, soil,biota, wind erosion}, doi = {10.1002/(SICI)1099-145X(199712)8:4<355::AID-LDR266>3.0.CO;2-H}, url = {files/bibliography/JRN00235.pdf}, author = {Jayne Belnap and D. E. Gillette} } @article {51293, title = {Factors controlling threshold friction velocity in semiarid and arid areas of the United States}, journal = {Journal of Geophysical Research}, volume = {102}, year = {1997}, note = {//??//LTER-III//}, month = {1997}, pages = {23277-23287}, abstract = {

A physical model was developed to explain threshold friction velocities u*t for particles of the size 60{\textendash}120 {\textmu}m lying on a rough surface in loose soils for semiarid and arid parts of the United States. The model corrected for the effect of momentum absorption by the nonerodible roughness. For loose or disturbed soils the most important parameter that controls u*t is the aerodynamic roughness height z0. For physical crusts damaged by wind the size of erodible crust pieces is important along with the roughness. The presence of cyanobacteriallichen soil crusts roughens the surface, and the biological fibrous growth aggregates soil particles. Only undisturbed sandy soils and disturbed soils of all types would be expected to be erodible in normal wind storms. Therefore disturbance of soils by both cattle and humans is very important in predicting wind erosion as confirmed by our measurements.

}, keywords = {eolian, physical model, soil crusts, soil disturbance, threshold friction velocity, wind erosion}, doi = {10.1029/97JD01303}, url = {files/bibliography/JRN00237.pdf}, author = {B{\'e}atrice Marticorena and Gilles Bergametti and D. E. Gillette and Jayne Belnap} } @article {51627, title = {Field evaluation of relationships between a vegetation structural parameter and sheltered against wind erosion}, journal = {Land Degradation and Rehabilitation}, volume = {2}, year = {1990}, note = {//USDA//LTER II//Listed in LTER3 proposal as citing LTER2 support//updated 08/19/2008}, month = {1990}, pages = {87-94}, abstract = {

Measurements of natural vegetation canopies and of threshold friction velocities for soil movement was made at three arid and semiarid field sites. Threshold friction velocities for the vegetated surface and for bare soil were used to evaluate the partitioning of shear stress between that absorbed by the plant canopies and that absorbed by the soil surface (this potentially causing movement of soil particles). Canopy measurements were used to estimate lateral cover (total frontal-silhouette area per unit ground area), a parameter shown by previous laboratory studies to be a good predictor of shear stress partitioning. The relationship between lateral cover and shear stress partitioning for the field sites agreed with the laboratory results of Gillette and Stockton (1989). Results indicate that the protective influence of vegetative cover against wind erosion can be successfully predicted using simply measurement s of vegetation canopy structure.

}, keywords = {aeolian processes, canopy structure, aeolian processes, roughness elements, aeolian processes, shear stress partitioning, article, articles, desert winds, erosion threshold, Geomet, journal, journals, shear stress partitioning, aeolian processes, soil erosion, wind erosion}, doi = {10.1002/ldr.3400020203}, url = {files/bibliography/JRN00123.pdf}, author = {Musick, H. B. and D. E. Gillette} }