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Title: Estimating conservation needs for rangelands using USDA National Resources Inventory Assessments

Author
item Weltz, Mark
item JOLLEY, LEONARD - NATURAL RESOURCES CONSERVATION SERVICE (NRCS, USDA)
item HERNANDEZ, MARIANO - UNIVERSITY OF ARIZONA
item SPAETH, KEN - NATURAL RESOURCES CONSERVATION SERVICE (NRCS, USDA)
item ROSSI, COLLEEN - BUREAU OF LAND MANAGEMENT
item TALBOT, CURTIS - NATURAL RESOURCES CONSERVATION SERVICE (NRCS, USDA)
item Nearing, Mark
item STONE, JEFFRY
item Goodrich, David - Dave
item WEI, HAIYAN - UNIVERSITY OF ARIZONA
item Pierson, Fred
item MORRIS, CHRISTOPHER

Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2014
Publication Date: 9/30/2014
Citation: Weltz, M.A., Jolley, L., Hernandez, M., Spaeth, K., Rossi, C., Talbot, C., Nearing, M.A., Stone, J.J., Goodrich, D.C., Wei, H., Pierson Jr, F.B., Morris, C.E. 2014. Estimating conservation needs for rangelands using USDA National Resources Inventory Assessments. American Society of Agricultural and Biological Engineers. 57(6):1-12.

Interpretive Summary: The USDA-Natural Resources Conservation Service (NRCS) has used resource inventories for over 65 years to assess the Nation’s natural resources on non-Federal lands. Since 1995, an interagency group composed of the NRCS, Agricultural Research Service, and Geological Survey have worked together to develop a robust field approach for the National Resource Inventory (NRI) on rangeland. The new NRI protocols are designed to detect long-term, years to decades, changes in the condition of rangeland ecosystems, and monitor short-term impacts, which may be of immediate concern. A new process based model was developed by ARS for assessing soil erosion rates on rangelands in support of the Conservation Effects Assessment Project and the NRI. The Rangeland Hydrology and Erosion Model (RHEM) was developed on data collected exclusively from rangeland erosion experiments. The RHEM tool was used to estimate runoff and erosion at the hillslope scale for over 10,000 NRI sample points in the 17 western states on non-Federal rangelands. National average annual erosion rate on non-Federal rangeland is estimated to be 1.41 ton ha-1 year-1. Nationally 20% of non-Federal rangelands generate over 65% of the average annual soil loss. Over 18% of the non-Federal rangelands might benefit from treatment to reduce soil loss to below 2.24 ton ha-1 year-1. National average annual erosion rates combine areas with low and accelerated soil erosion. Evaluating data in this manner can misrepresent the magnitude of the soil erosion problem on rangelands. We estimate currently that between 23 and 29% of the Nation’s rangelands are vulnerable to accelerated soil loss (soil erosion > 2.24 ton ha-1 event -1) if assessed as a function of vulnerability by using the risk of a runoff event of a given magnitude (25 or 50 year return storm event). NRCS has not evaluated potential erosion risk in National reports in the past and adaptation of this technique will allow USDA and its partners to be proactive in preventing accelerated soil loss on rangelands.

Technical Abstract: The USDA-Natural Resources Conservation Service (NRCS) has used resource inventories for over 65 years to assess the Nation’s natural resources on non-Federal lands. Since 1995, an interagency group composed of the NRCS, Agricultural Research Service, and Geological Survey have worked together to develop a robust field approach for the National Resource Inventory (NRI) on rangeland. The new NRI protocols are designed to detect long-term, years to decades, changes in the condition of rangeland ecosystems, and monitor short-term impacts, which may be of immediate concern. A new process based model was developed by ARS for assessing soil erosion rates on rangelands in support of the Conservation Effects Assessment Project and the NRI. The Rangeland Hydrology and Erosion Model (RHEM) was developed on data collected exclusively from rangeland erosion experiments, and is designed to use data that is routinely collected by rangeland managers. The RHEM tool was used to estimate runoff and erosion at the hillslope scale for over 10,000 NRI sample points in the 17 western states on non-Federal rangelands. National average annual erosion rate on non-Federal rangeland is estimated to be 1.41 ton ha-1 year-1. Nationally 20% of non-Federal rangelands generate over 65% of the average annual soil loss. Over 29.2 x 106 ha or 18% of the non-Federal rangelands might benefit from treatment to reduce soil loss to below 2.24 ton ha-1 year-1. National average annual erosion rates combine areas with low and accelerated soil erosion. Evaluating data in this manner can misrepresent the magnitude of the soil erosion problem on rangelands. We estimate currently that between 23 and 29% of the Nation’s rangelands are vulnerable to accelerated soil loss (soil erosion > 2.24 ton ha-1 event -1) if assessed as a function of vulnerability by using the risk of a runoff event of a given magnitude (25 or 50 year return storm event). NRCS has not evaluated potential erosion risk in National reports in the past and adaptation of this technique will allow USDA and its partners to be proactive in preventing accelerated soil loss on rangelands.