@conference {JRN55422, title = { Invasive plant species effects on wind and water erosion across US grazing lands }, booktitle = {LTAR Annual Meeting}, year = {2021}, month = {7/16/2021}, abstract = {Soil erosion by wind and water reduces the productive potential of agroecosystems, threatening the efficacy of climate change mitigation and adaption, and strategies for the sustainable intensification of agriculture. The extensive US grazing lands encompass diverse ecosystems with different inherent resistance and resilience to erosion. Land uses, land management, and disturbances vary across these regions and have great potential to change (accelerate or reduce) soil erosion rates. Over the last century, a combination of land management pressures (e.g., grazing), altered fire regimes, drought, and climate change have facilitated establishment and spread of invasive plant species across grazing lands, which has directly and indirectly affected the susceptibility of sites to soil erosion. The LTAR Rangeland Soil Erosion Working Group is collaborating with natural resource agencies (NRCS and BLM) to understand how invasive plant species are influencing wind and water erosion across public and private grazing lands, and where conservation practices may be most effective. We are applying the Aeolian Erosion (AERO) model and Rangeland Hydrology and Erosion Model (RHEM) to estimate aeolian sediment transport and water erosion rates using monitoring datasets collected by the NRCS and BLM at over 60,000 locations and harmonized in the Landscape Data Commons. The erosion indicators are being assessed relative to indicators of vegetation cover and structure, including invasive and native species, which attenuate soil erosion. We hypothesize that vegetation cover and structure are influenced by the presence and cover of invasive plant species, and that modelled indicators of soil erosion are responding across ecoregions.}, keywords = {erosion, Invasive plant, species, US grazing lands, water, wind}, author = {Nicholas Webb and Sarah McCord and Kristopher Bonefont and Ericha Courtright and Danielle Duni and Brandon Edwards and David C. Goodrich and Phil Heilman and Mariano Hernandez and Lori Metz and Daniel N. Moriasi and Mark A. Nearing and Beth Newingham and Nichols, Mary H. and Frederick B. Pierson and John Tatarko and David P. Toledo and Scott Van Pelt and Justin Van Zee and Jason Williams} } @article {JRN55346, title = {Size distribution of mineral dust emissions from sparsely vegetated and supply-limited dryland soils}, journal = {Journal of Geophysical Research: Atmospheres}, volume = {126}, year = {2021}, month = {11/08/2022}, pages = {e2021JD035478}, abstract = {Controls on the particle size distribution (PSD) of mineral dust emissions remain poorly understood. Under near-idealized conditions, dust PSDs can appear invariant with wind friction velocity. However, dryland vegetation attenuates surface friction velocities, and soil crusting reduces the supply of loose erodible material and increases surface resistance to abrasion. Under such conditions, variability in saltation bombardment efficiency and intensity could have a large effect on dust PSDs. We present dust emission measurements from vegetated, supply-limited aeolian systems that indicate the dependence of emission-flux PSD on wind friction velocity. We find the fine fraction (<5 μm) of dust particles increases with friction velocity. Results suggest models that assume wind-invariance of the emission-flux PSD may not be generalizable for crusted soils with vegetation. There is a need for dust models to represent variability in emission-flux PSDs for land management, air quality, and climate applications across vegetated and sediment supply-limited drylands.}, keywords = {Mineral Dust Emissions, Size Distribution, soils, Supply-Limited Dryland Soils, Vegetated}, doi = {10.1029/2021JD035478}, url = {files/bibliography/21-055.pdf}, author = {Nicholas Webb and Susan LeGrand and Brad Cooper and Ericha Courtright and Brandon Edwards and Christopher Felt and Justin Van Zee and N. Ziegler} } @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} } @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 {JRN55216, title = {Ecosystem dynamics and aeolian sediment transport in the southern Kalahari}, journal = {African Journal of Ecology}, volume = {58}, year = {2020}, month = {06/2020}, pages = {337-344}, chapter = {337}, abstract = {Aeolian sediment transport processes are sensitive to dryland ecosystem change and can contribute to the transition of savanna grasslands to shrub-invaded and shrub-dominated states. In the southern Kalahari savanna, bush encroachment by Senegalia mellifera is a pervasive ecosystem change that creates mosaic landscapes of varying density grasses and bushes that can affect patterns of aeolian sediment transport. Herbaceous species losses and bush encroachment in the Kalahari have been associated with increased dune mobility, degraded air quality, and potential reactivation of the region as a persistent dust source. While accelerated wind erosion can be both driver and consequence of ecosystem change in the Kalahari, the role of aeolian processes and its regional impacts have not been fully established. Here, we examine preliminary data on the influence of southern Kalahari ecosystem changes on surface aerodynamic roughness and aeolian sediment transport as a basis for understanding their interactions.}, doi = {https://doi.org/10.1111/aje.12700}, url = {files/bibliography/20-026.pdf}, author = {Nicholas Webb and Gregory S. Okin and Abinash Bhattachan and Paolo D{\textquoteright}Odorico and Dintwe, Kebonye and Tatlhego, Mokganedi} } @article {JRN55156, title = {Indicators and benchmarks for wind erosion monitoring, assessment and management}, journal = {Ecological Indicators}, volume = {110}, year = {2020}, month = {01/10/2020}, abstract = {

Wind erosion and blowing dust threaten food security, human health and ecosystem services across global drylands. Monitoring wind erosion is needed to inform management, with explicit monitoring objectives being critical for interpreting and translating monitoring information into management actions. Monitoring objectives should establish\ quantitative guidelines for determining the relationship of wind erosion indicators to management benchmarks that reflect tolerable erosion and dust production levels considering impacts to, for example, ecosystem processes, species, agricultural production systems and human well-being. Here we: 1) critically review indicators of wind erosion and blowing dust that are currently available to practitioners; and 2) describe approaches for establishing benchmarks to support wind erosion assessments and management. We find that while numerous indicators are available for monitoring wind erosion, only a subset have been used routinely and most monitoring efforts have focused on air quality impacts of dust. Indicators need to be related to the causal soil and vegetation controls in eroding areas to directly inform management. There is great potential to use regional standardized soil and vegetation monitoring datasets, remote sensing and models to provide new information on wind erosion across landscapes. We identify best practices for establishing benchmarks for these indicators based on experimental studies, mechanistic and empirical models, and distributions of indicator values obtained from monitoring data at historic or existing reference sites. The approaches to establishing benchmarks described here have enduring utility as monitoring technologies change and enable managers to evaluate co-benefits and potential trade-offs among ecosystem services as affected by wind erosion management.

}, keywords = {adaptive management, aeolian, Air quality, dust, ecological thresholds, Reference site}, doi = {10.1016/j.ecolind.2019.105881}, url = {files/bibliography/20-001.pdf}, author = {Nicholas Webb and Emily Kachergis and Scott W. Miller and Sarah McCord and Brandon T Bestelmeyer and Joel R. Brown and A. Chappell and Brandon Edwards and Jeffrey E. Herrick and Jason W. Karl and John Leys and Loretta Metz and Steve Smarik and John Tatarko and Justin Van Zee and G. Zwicke} } @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 {JRN55094, title = {Reducing sampling uncertainty in aeolian research to improve change detection}, journal = {Journal of Geophysical Research}, volume = {124}, year = {2019}, month = {04/2019}, pages = {1-12}, chapter = {1}, abstract = {

Measurements of aeolian sediment transport support our understanding of the process mechanics, dust model parameterization, and assessments of the sensitivity of the dust cycle to environmental change. However, sample design principles are often overlooked in aeolian research. Here, we use high-density measurements of sediment mass flux across land use and land cover types to examine sample size and power effects on detecting change in aeolian transport. Spatial variances accounted for 5\% to 45\% of total with-in site variances in aeolian transport. Differences in transport were detectable for \<20\% of comparisons at sites with large spatial variability. Failure to detect change with intensive sampling suggests that aeolian research is very likely to be much more uncertain than recognized. We show small and selective sampling, common in aeolian research, gives the false impression that differences in aeolian transport can be detected, potentially undermining inferences about process and impacting reproducibility of aeolian research.

}, doi = {doi.org/10.1029/2019JF005042}, url = {files/bibliography/19-010.pdf}, author = {Nicholas Webb and A. Chappell and Brandon Edwards and Sarah McCord and Justin Van Zee and Brad Cooper and Ericha Courtright and Danielle Duni and Brenton Sharrat and Negussie Tedela} } @conference {JRN55061, title = {How to detect change in aeolian sediment transport}, booktitle = {International Conference on Aeolian Research}, year = {2018}, month = {06/2018}, address = {Bordeaux, France}, abstract = {

The detection of change in aeolian sediment transport is key to explaining cause. For example, anthropogenic land use and land cover change (LULCC) influence global rates of wind erosion and dust emission. However, current approaches to measuring wind erosion and dust emission are typically highly uncertain, because they inadequately account for the large spatial and temporal variation in aeolian sediment transport. Field measurements need to reduce uncertainty sufficiently to enable change to be detected at some specified confidence level. Here, we use field measurements of aeolian sediment transport to show (Figure 1) that: i) the spatial variance in aeolian sediment transport may be many times larger than the temporal variance depending on the land surface aerodynamics and sediment supply; and ii) too few samplers, or poorly positioned (biased, e.g., by avoiding vegetation) samplers inflate uncertainty causing change in aeolian sediment transport to be undetectable. The straightforward application of an unbiased sampling design combined with a rigorous statistical framework enables minimum detectable change over time in aeolian sediment transport responding to e.g., land use and management across land cover types. We examine how robust field measurements can be combined with new modelling approaches that resolve the spatial variation in transport controls to improve dust model sensitivity and reduce uncertainty in assessments of the impacts of LULCC.

}, author = {Nicholas Webb and A. Chappell and Justin Van Zee and Brandon Edwards and D. K. James} } @conference {JRN55062, title = {A more or less dusty future?}, booktitle = {Ecological Society of America Meeting}, year = {2018}, month = {08/2018}, address = {New Orleans, Louisiana}, abstract = {

Wind erosion and blowing dust impact air quality, biogeochemical cycles, the hydrologic cycle and climate, and are major resource concerns for land managers; but where is all the dust coming from, and why? Will there be more, or less, dust in the future? How we will answer these questions presents numerous research challenges with consequences for human health, ecosystem services, and how we prepare agriculture to meet food and fiber demands under a changing climate. I will explore these challenges and identify opportunities for new interdisciplinary research to tackle them.

}, author = {Nicholas Webb} } @proceedings {JRN54862, title = {Multi-scale wind erosion monitoring and assessment for US rangelands}, volume = {January 28-February 2, 2018}, year = {2018}, month = {01/28/2018}, publisher = {Society for Range Management Meeting Proceedings}, address = {Reno, NV}, abstract = {

Wind erosion is a major resource concern for rangeland managers. Although wind erosion is a naturally occurring process in many drylands, land use activities, and land management in particular, can accelerate wind-driven soil loss {\textendash} impacting ecosystem dynamics and agricultural production, air quality, human health, biogeochemical cycles, and climate. Wind erosion has large variability in space and time, and as a consequence is difficult to monitor effectively in ways that can support its management. Existing US air quality monitoring programs provide indicators of wind erosion intensity (e.g., particulate matter [PM] concentrations) and associated benchmarks (e.g., Clean Air Act) are regulated federally but provide no information about which landscapes are eroding, but how much, or when. Standardized rangeland monitoring programs like the BLM{\textquoteright}s Assessment, Inventory and Monitoring (AIM) Strategy and the NRCS{\textquoteright}s National Resources Inventory (NRI) collect information about soil properties (texture) and vegetation (foliar cover, canopy gap size, height) that, coupled with remote sensing products and numerical models, can be used to estimate wind erosion and dust emission rates across spatial scales to better inform management. Here I present an overview of the National Wind Erosion Research Network and ongoing efforts to develop decision-support tools that connect existing soil, vegetation and air quality monitoring programs to provide information to federal agencies and the public about wind erosion rates. I demonstrate how core indicators used in the AIM and NRI monitoring programs can be integrated to assess dust emission rates; enabling air quality, human health and ecosystem impacts of dust to be linked to changes in range condition and benchmarks for rangeland management. I then describe how AIM and NRI data can be used to interpret remote sensing-driven model estimates of wind erosion and understand interactions with land use and management activities across ecological sites.

}, author = {Nicholas Webb} } @article {JRN54794, title = {Enhancing wind erosion monitoring and assessment for US rangelands}, journal = {Rangelands}, volume = {39}, year = {2017}, month = {09/2017}, pages = {85-96}, chapter = {85}, abstract = {

Wind erosion is a major resource concern for rangeland managers because it can impact soil health, ecosystem structure and function, hydrologic processes, agricultural production and air quality. \ Despite its significance, little is known about which landscapes are eroding, by how much, and when. \ The National Wind Erosion Research Network was established in 2014 to develop tools for monitoring and assessing wind erosion and dust emission across the U.S. The Network, currently consisting of 13 sites, creates opportunities to enhance existing rangeland soil, vegetation and air quality monitoring programs. \ Decision-support tools developed by the Network will improve the prediction and management of wind erosion across rangeland ecosystems.

}, doi = {10.1016/j.rala.2017.04.001}, url = {files/bibliography/17-016.pdf}, author = {Nicholas Webb and Justin Van Zee and Jason W. Karl and Jeffrey E. Herrick and Ericha Courtright and Billings, Benjamin and Boyd, Robert and A. Chappell and Danielle Duni and J. D. Derner and Hand, Jenny and Emily Kachergis and Sarah McCord and Beth Newingham and Frederick B. Pierson and Jean Steiner and John Tatarko and Negussie Tedela and David P. Toledo and Scott Van Pelt} } @article {JRN54799, title = {Land degradation and climate change: building climate resilience in agriculture}, journal = {Frontiers in Ecology and the Environment}, volume = {15}, year = {2017}, month = {10/2017}, pages = {450-459}, chapter = {450}, abstract = {

Land degradation and climate change pose enormous risks to global food security. Land degradation increases the vulnerability of agroecological systems to climate change and reduces the effectiveness of adaptation options. Yet these interactions have largely been omitted from climate impact assessments and adaptation planning. We examine how land degradation can influence climate-change impacts and the adaptive capacity of crop and livestock producers across agroecological systems. We then present novel strategies for climate-resilient agriculture that support opportunities to integrate responses to these challenges. Forward-looking, climate-resilient agriculture requires: (1) incorporation of land degradation processes, and their linkages with adaptive capacity, into adaptation planning; (2) identification of key vulnerabilities to prioritize adaptation responses; (3) improved knowledge exchange across local to global scales to support strategies for developing the adaptive capacity of producers; and (4) innovative management and policy options that provide multiple {\textquotedblleft}wins{\textquotedblright} for land, climate, and biodiversity, thus enabling global development and food security goals to be achieved.

}, doi = {doi:10.1002/fee.1530}, url = {files/bibliography/17-023.pdf}, author = {Nicholas Webb and Marshall, Nadine and Stringer, Lindsay and Reed, Mark and A. Chappell and Jeffrey E. Herrick} } @conference {JRN54672, title = {Using state-and-transition models to evaluate impacts of land cover change on wind erosion}, booktitle = {Society for Range Management Meeting Abstracts}, volume = {Jan 29 - Feb 02, 2017}, year = {2017}, month = {01/2017}, abstract = {
Wind erosion of rangeland soils is a global problem exacerbated by land cover change. Despite efforts to quantify the impacts of land cover change on wind erosion, assessment uncertainty remains large. We address this uncertainty by evaluating the application of ecological sites and state-and-transition models for detecting and describing the impacts of land cover change on wind erosion. We couple a geodatabase of ecological site information with atmospheric data from the Weather Research and Forecasting (WRF) model to run a dust emission model at 1 km spatial resolution over a study area in the northern Chihuahuan Desert, New Mexico, USA. We evaluate spatiotemporal patterns of modelled horizontal sediment mass flux and dust emission in the context of ecological sites and their states; representing a diversity of land cover types. Our results demonstrate how the impacts of land cover change on wind erosion can be quantified, compared across land cover classes, and interpreted in the context of an ecological model that encapsulates land management intensity and change. Results also reveal weaknesses in the dust emission model{\textquoteright}s soil characterisation and drag partition scheme, which were largely insensitive to the impacts of land cover change. New models that address these weaknesses, coupled with the ecological site framework and field measurements across land cover types, could significantly reduce assessment uncertainties and provide opportunities for identifying land management options.
}, author = {Nicholas Webb and Magda Galloza and M. Bleiweiss and Craig Winters and E.L. Ayers and Jeffrey E. Herrick} } @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.} } @conference {JRN54637, title = {The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management}, booktitle = {9th International Conference on Aeolian Research}, year = {2016}, month = {07/2016}, publisher = {International Conference on Aeolian Research}, organization = {International Conference on Aeolian Research}, address = {Mildura, Australia}, abstract = {
The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the USDA Agricultural Research Service and Natural Resources Conservation Service, and USDI Bureau of Land Management, to address the need for a broad and coordinated research program to develop wind erosion research and management in the United States. The National Wind Erosion Research Network has three general aims: 1) provide data to support understanding of basic aeolian processes across land use and land cover types and for different management practices, 2) support the development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and 3) encourage collaboration between the aeolian research community and land management agencies to increase the impact of aeolian research for the wider community. By applying standardized methods, the Network will overcome the common challenge of synthesizing independent studies to assess local-to-national scale wind erosion and dust emission and their impacts. Twelve intensively instrumented Network sites will be operational in 2016, providing high-resolution measurements of aeolian sediment transport rates, meteorological conditions and soil and vegetation properties that influence dust emission, transport and deposition. These initial sites are located across the rangelands, croplands and deserts of New Mexico, Texas, Arizona, California, Colorado, Utah, North Dakota, Idaho and Washington. In support of Network activities, winderosionnetwork.org was developed to serve as a data portal and access to online information about the National Wind Erosion Research Network, including site descriptions, measurement protocols and results. The website provides a comprehensive resource for scientists and managers interested in collaborating with the Network and accessing Network data products. The Network provides exciting opportunities to engage in a national long-term wind erosion research program that promises significant impact for our understanding and ability to predict and evaluate aeolian processes across land cover types and land use systems.
}, author = {Nicholas Webb and Jeffrey E. Herrick and Justin Van Zee and Ericha Courtright and Brad Cooper and Valerie LaPlante} } @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 {JRN54607, title = {Using albedo to reform wind erosion modelling, mapping and monitoring}, journal = {Aeolian Research}, volume = {23}, year = {2016}, month = {12/2016}, chapter = {63}, abstract = {
Dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. We describe a need in aeolian research to adequately represent the spatial variability and particularly the area average of the key aerodynamic properties which influence these models and our understanding of the processes. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth{\textquoteright}s surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and its latent influence on roughness configuration and demonstrate that significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted particularly under sparse surface roughness (0.001\<L\<0.1). We describe a solution which develops earlier work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas across platforms from the field to airborne and readily available data from satellite remote sensing. The approach also demonstrated redundancy in existing wind erosion models and thereby reduced their complexity but improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise drag partition and predict sediment transport without the use of a drag partition scheme and the entrainment threshold. We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional approach to wind erosion modelling. The global maps identified regions of small aerodynamic roughness previously thought to be susceptible to wind erosion because of their erodibility. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not be detected using traditional models. The work shows how this new approach provides new opportunities to investigate the dynamics of wind erosion in space and time and elucidate aeolian processes across scales.
}, doi = {http://dx.doi.org/10.1016/j.aeolia.2016.09.006}, url = {files/bibliography/16-030.pdf}, author = {Nicholas Webb and A. Chappell} } @conference {JRN54208, title = {A national wind erosion research network}, booktitle = {18th International Soil Conservation Organization Conference}, year = {2015}, month = {05/2015}, address = {El Paso, Texas}, abstract = {

Public concern about wind erosion in the United States is high. This concern has arisen as a consequence of changing and intensifying land use pressures which can lead to increased soil loss and dust emission. However, there is relatively little research to support improved management. While much attention has been given to measuring and modelling wind erosion in US croplands, little information is available on the magnitude and frequency of wind erosion in rangelands and other land cover types. Resolving this knowledge gap is important for soil conservation in the face ongoing land use change, land cover change and climate change. Predictive models supported by high quality, spatially-diverse field measurements are needed to quantify wind erosion across all land cover types so that the impacts can be assessed and management options identified and tested. We present a National Wind Erosion Research Network to support field assessments of wind erosion in all land cover types and the development of an all-lands wind erosion model. We describe the establishment of the network field sites, supported by the US Department of Agriculture{\textquoteright}s Long-Term Agroecosystem Research (LTAR) network, Natural Resources Conservation Service (NRCS), Bureau of Land Management (BLM), and Department of Defence (DoD), and outline a standard methods protocol developed to ensure consistency in wind erosion monitoring and assessment across the network. The network will provide opportunities to evaluate controls on the timing and intensity of wind erosion across land use and land cover types in the United States. These data, in support of an all-lands wind erosion model, will provide much needed tools for managing wind erosion and its impacts.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Hugenholtz, Christopher and Teddy M. Zobeck and Gregory S. Okin} } @conference {JRN54497, title = {winderosionnetwork.org {\textendash} Portal to the National Wind Erosion Research Network}, booktitle = {AGU Fall Meeting}, year = {2015}, month = {12/2015}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the USDA Agricultural Research Service and Natural Resources Conservation Service, and USDI Bureau of Land Management, to address the need for standardized measurements of wind erosion and its controlling factors. Data will be used to support model development and identification of improved land management strategies that have global applications. By applying standard methods, the Network will overcome the common challenge of synthesizing independent studies to assess local-to-national scale wind erosion and dust emission. Twelve intensively instrumented Network sites will be operational by spring 2016, providing high-resolution measurements of aeolian sediment transport rates, meteorological conditions and soil and vegetation properties. These initial sites are located across rangelands and croplands in New Mexico, Texas, Arizona, California, Nevada, Colorado, Utah, North Dakota, Idaho and Washington. A primary objective of the Network is to facilitate collaboration among Network sites and the wider research community to address basic research questions about aeolian processes, model development, and evaluate practical management options. In support of Network activities, winderosionnetwork.org was developed to serve as a Network data portal, and provide online information about the National Wind Erosion Research Network including protocols and results. The website provides a comprehensive resource for scientists and managers interested in engaging with the Network and accessing Network products. The Network provides exciting opportunities to engage in a national long-term wind erosion research program that promises significant impact for our understanding and ability to predict and evaluate aeolian processes across land cover types and land use systems.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Clingan, Scott and Brad Cooper and Ericha Courtright and Valerie LaPlante and Justin Van Zee} } @article {JRN54040, title = {Ecological site-based assessments of wind and water erosion: Informing accelerated soil erosion management in rangelands}, journal = {Ecological Applications}, volume = {24}, year = {2014}, month = {09/2014}, pages = {1405-1420}, chapter = {1405}, abstract = {

This paper explores how soil erosion assessments structured across ecological sites can inform systems for managing accelerated soil erosion in rangelands. We evaluated wind and water erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Our results show that wind and water erosion can be highly variable within and among ecological sites. Plots in shrub-encroached and shrub-dominated states were consistently susceptible to both wind and water erosion. However, grassland plots and plots with a grass-succulent mix had a high indicated susceptibility to wind and water erosion respectively. Vegetation thresholds for controlling erosion are identified that transcend the ecological sites and their respective states. The thresholds define vegetation cover levels at which rapid (exponential) increases in erosion rates begin to occur, suggesting that erosion in the study ecosystem can be effectively controlled when bare ground cover is \<20\% of a site or total ground cover is \>50\%. Similarly, our results show that erosion can be controlled when the cover of canopy interspaces \>50 cm in length reaches ~50\%, the cover of canopy interspaces \>100 cm in length reaches ~35\% or the cover of canopy interspaces \>150 cm in length reaches ~20\%. This process-based understanding can be applied, along with knowledge of the differential sensitivity of vegetation states, to improve erosion management systems. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of sites to erosion. Land use impacts that are constrained within the natural variability of sites should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds and natural variability of ecological sites will enable improved identification of where and when accelerated soil erosion occurs and the development of practical management solutions.

}, keywords = {accelerated soil erosion, aeolian, agriculture, anthropogenic dust, dryland, land use change, state-and-transisiton models, sustainability, threshold}, url = {/files/bibliography/14-027.pdf}, author = {Nicholas Webb and Jeffrey E. Herrick and Danielle Duni} } @article {JRN53969, title = {The effect of roughness elements on wind erosion: The importance of surface shear stress distribution}, journal = {Journal of Geophysical Research: Atmospheres}, volume = {119}, year = {2014}, month = {05/2014}, pages = {6066-6084}, chapter = {6066}, abstract = {

Representation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the vegetated land surface. This approach does not explicitly account for the effects of roughness configuration, which may be important for sediment flux. Here we investigate the significance of roughness configuration for Aeolian sediment transport, the ability of drag partitioning approaches to represent roughness configuration effects, and the implications for model accuracy. We use wind tunnel measurements of surface shear stress distributions to calculate sediment flux for a suite of roughness configurations, roughness densities, and wind velocities. Roughness configuration has a significant effect on sediment flux, influencing estimates by more than 1 order of magnitude. Measured and modeled drag partitioning approaches overestimate the predicted flux by 2 to 3 orders of magnitude. The drag partition is sensitive to roughness configuration, but current models cannot effectively represent this sensitivity. The effectiveness of drag partitioning approaches is also affected by estimates of the aerodynamic roughness height used to calculate wind shear velocity. Unless the roughness height is consistent with the drag partition, resulting fluxes can show physically implausible patterns. These results should make us question current assessments of the magnitude of vegetated dryland dust emissions. Representing roughness effects on surface shear stress distributions will reduce uncertainty in quantifying wind erosion, enabling better assessment of its impacts and management solutions.

}, doi = {10.1002/2014JD021491}, url = {/files/bibliography/14-020.pdf}, author = {Nicholas Webb and Gregory S. Okin and Brown, Shannon} } @proceedings {JRN54043, title = {A National Wind Erosion Monitoring Network to support and all-lands wind erosion model}, year = {2014}, month = {07/2014}, pages = {p. 427}, publisher = {International Society of Aeolian Research (ISAR)}, address = {Lanzhou, China}, abstract = {

Public concern about wind erosion in the United States rangelands is increasing. This concern has arisen as a consequence of changing and intensifying land use pressures which can lead to increased soil loss and dust emissions. However, there is relatively little research to support improved management. While much attention has been given to measuring and modelling wind erosion in US cropping systems, there is a dearth of information on the magnitude and frequency of wind erosion in rangelands and other land cover types. Resolving this knowledge gap is important for addressing the multiple impacts of land use and land cover change, including those related to soil nutrient loss and productivity, snow hydrology, public health and climate. Field measurements of aeolian sediment transport rates supported by predictive models are needed to quantify wind erosion across all land cover types so that the impacts can be assessed and management solutions identified and tested. We present a new National Wind Erosion Monitoring Network to support field assessments of wind erosion in all land cover types and the development of an all-lands wind erosion model. We describe the establishment of the network field sites, supported by the US Department of Agriculture\’s Long-Tern Agroecosystem Research (LTAR) network, Natural Resources Conservation Service and Bureau of Land Management, and outline a standard methods protocol developed to ensure consistency in wind erosion monitoring and assessment across the network. The network will provide opportunities to evaluate controls on the timing and intensity of wind erosion in a number of land uses and land cover types across the United States. These data, in support of an all-lands wind erosion model, will provide much needed tools for managing wind erosion and its impacts.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Hugenholtz, Christopher and Gregory S. Okin and Teddy M. Zobeck} } @proceedings {JRN54042, title = {Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion}, year = {2014}, month = {07/2014}, pages = {p. 357}, publisher = {International Society of Aeolian Research (ISAR)}, address = {Lanzhou, China}, abstract = {

This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Our results show that sediment transport and erosion can be highly variable within and among ecological sites. Plots in shrub-encroached and shrub-dominated states were consistently susceptible to both aeolian sediment transport and fluvial erosion. However, grassland plots and plots with a grass-succulent mix had a high indicated susceptibility to wind and water erosion respectively. Vegetation thresholds for controlling erosion are identified that transcend the ecological sites and their respective states. The thresholds define vegetation cover levels at which rapid (exponential) increases in sediment transport and erosion rates begin to occur, suggesting that erosion in the study ecosystem can be effectively controlled when bare ground cover is \<20\% of a site or total ground cover is \>50\%. Similarly, our results show that erosion can be controlled when the cover of canopy interspaces \>50 cm in length reaches ~50\%, the cover of canopy interspaces \>100 cm in length reaches ~35\% or the cover of canopy interspaces \>150 cm in length reaches ~20\%. This process-based understanding can be applied, along with knowledge of the differential sensitivity of vegetation states, to improve erosion management systems. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of sites to erosion. Land use impacts that are constrained within the natural variability of sites should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds and natural variability of ecological sites will enable improved identification of where and when accelerated soil erosion occurs and the development of practical management solutions.

}, author = {Nicholas Webb and Jeffrey E. Herrick and Danielle Duni} } @proceedings {JRN54041, title = {Roughness configuration matters for aeolian sediment flux}, year = {2014}, month = {07/2014}, pages = {p. 12}, publisher = {International Society of Aeolian Research (ISAR)}, address = {Lanzhou, China}, abstract = {

The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of shear stress on roughness elements to that on the vegetated land surface. However, the approach does not explicitly account for the effects of roughness configuration, which may be important for sediment flux. In this study we investigate (1) the significance of roughness configuration for aeolian sediment transport, (2) the ability of drag partitioning approaches to represent roughness configuration effects, and (3) the implications of our findings for model applications. We use wind tunnel measurements of surface shear stress distributions to calculate sediment flux for a suite of roughness configurations, roughness densities and wind velocities. Our results show that roughness configuration has a significant effect on sediment flux, influencing estimates by more than one order-of-magnitude. Measured and modelled drag partitioning approaches overestimate the predicted flux by two to three orders-of-magnitude. The drag partition is sensitive to roughness configuration, but current models cannot effectively represent this sensitivity. The effectiveness of drag partitioning approaches is also affected by estimates of the aerodynamic roughness height (z0) used to calculate wind shear velocity (u*). Unless the roughness height is consistent with the drag partition and u*t, resulting fluxes can show physically implausible patterns. These results should make us question current assessments of the magnitude of vegetated dryland dust emissions. Representing roughness effects on surface shear stress distributions will reduce uncertainty in quantifying wind erosion, enabling better assessment of its impacts and management solutions.

}, author = {Nicholas Webb and Gregory S. Okin and Brown, Shannon} } @proceedings {JRN54045, title = {Soil organic carbon dust emission: a synthesis of recent Australian research }, year = {2014}, month = {07/2014}, pages = {p. 196}, publisher = {International Society of Aeolian Research (ISAR)}, address = {Lanzhou, China}, abstract = {

Soil erosion is an important component of the global carbon cycle. Recent research has revealed the importance of aeolian processes for soil organic carbon (SOC) flux and its impacts on carbon dynamics and ecosystem function. Here we review progress in research on the mechanisms and magnitude of SOC dust emissions in Australia. We describe how field measurements of entrainment and enrichment of SOC in dust led to a new physically-based parameterisation of SOC dust enrichment for the Computational Environmental Management System (CEMSYS) national wind erosion model. Our modelling results suggest that from 2000-2011 the total dust emission for Australia was 118 Mt yr-1 with SOC dust emissions (\<22 \µm) ~1.59 Mt yr-1. Rangelands produced ~84\% of Australia\’s SOC dust emissions (1.34 Mt yr-1). Agricultural lands produced ~0.11 Mt yr-1, but emissions were larger per unit area than rangelands. The rapid and often long-distance aeolian transport of SOC may result in the depletion of SOC at source, enrichment of downwind soils, or incorporation into aquatic and marine systems. SOC loss was likely greater in the past (since 1870s) during post-colonial agricultural expansion and reduced since the 1980s with conservation agriculture. This impacted soil function and productivity of rangelands and cropping lands. The impact on land surface\–atmosphere interactions is likely also considerable, but large uncertainty remains over mineralisation rates of SOC and its fate in the atmosphere. Our results demonstrate the need for aeolian processes to be given greater significance in terrestrial carbon cycling, and for the inclusion of dust emission schemes in Earth systems models and carbon accounting systems.

}, author = {Nicholas Webb and A. Chappell and Craig Strong and Harry Butler and Samuel K. Marx and John Leys and Grant McTainish and Viscarra-Rossell, Raphael} } @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 {JRN54541, title = {Implications of carbon dust emission for terrestrail carbon cycling and carbon accounting}, volume = {A33D-0184}, year = {2012}, month = {12/2012}, publisher = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {Wind erosion preferentially removes the finest carbon- and nutrient-rich soil fractions, and consequently its role may be significant within terrestrial carbon (C) cycles. However, the impacts of wind erosion on soil organic carbon (SOC) redistribution are not considered in most carbon cycle models, or within national carbon accounting schemes. Current estimates of the loss of SOC to wind erosion do not consider the preferential removal and enrichment of SOC in dust emissions, and consequently underestimate the significance of carbon dust emissions for the carbon cycle and carbon accounting. We present a process-based approximation of SOC enrichment within the Computational Environmental Management System (CEMSYS v5) Australian national wind erosion model. It enabled the prediction of carbon dust emission at a 50 km spatial resolution across Australia each month from 2000{\textendash}2011. Our results show that the total dust emission for Australia is 118 Mt yr-1, with carbon dust emissions (<22 {\textmu}m) in the order of 1.59 Mt yr-1. Rangelands are found to produce ~84\% of Australia{\textquoteright}s carbon dust emissions (1.34 Mt yr-1), while agricultural lands produce 0.11 Mt yr-1. However, agricultural lands produce larger carbon dust emissions per km2 than rangelands. The long-distance transport of SOC by wind is expected to result in large mineralisation rates due to (e.g.) photochemical oxidation, and the release of up to 5.9 Mt CO2-e yr-1. These results on the loss of SOC in dust, and the release of CO2 during long-distance transport, demonstrate the need for aeolian processes to be given greater significance in terrestrial carbon cycling, and for them to be incorporated into carbon accounting systems.}, author = {Nicholas Webb and A. Chappell and Harry Butler and Craig Strong and Grant McTainish and John Leys} } @article {49911, title = {The significance of carbon-enriched dust for global carbon accounting}, journal = {Global Change Biology}, volume = {18}, year = {2012}, month = {12/2012}, pages = {3275-3278}, chapter = {3275}, abstract = {

Soil carbon stores amount to 54\% of the terrestrial carbon pool and twice the atmospheric carbon pool, but soil organic carbon (SOC) can be transient. There is an ongoing debate about whether soils are a net source or sink of carbon, and understanding the role of aeolian processes in SOC erosion, transport and deposition is rudimentary. The impacts of SOC erosion by wind on the global carbon budget, and its importance for carbon accounting remain largely unknown. Current understanding of SOC losses to wind erosion is based on the assumption that the SOC content of eroded material is the same as that of the parent soils. However, measured enrichment factors for the SOC content of Australian dusts relative to parent soils show that the SOC content of dusts can be up to seven times (by weight) larger than that of source-area soils, with enrichment factors ranging from 1.67 to 7.09.\  Assuming dust emissions from the continent of ~110 Mt yr -l , SOC dust emissions would be 0.13{\textendash}4.65 Mt SOC yr {\textendash}l\  without enrichment but 0.94{\textendash}7.77 Mt SOC yr-l\  with enrichment; which represents an uncertainty of around 60\%.\  Representing SOC enrichment within dust emission models will reduce uncertainty in estimates of the impact of wind erosion on SOC flux and provide an approach for the inclusion of wind erosion processes in carbon accounting systems.

}, doi = {10.1111/j.1365-2486.2012.02780.x}, url = {/files/bibliography/12-038.pdf}, author = {Nicholas Webb and A. Chappell and Craig Strong and Samuel K. Marx and Grant McTainish} }