Author
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Weltz, Mark |
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SPAETH, KEN - Natural Resources Conservation Service (NRCS, USDA) |
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Submitted to: Rangelands
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/1/2012 Publication Date: 8/1/2012 Citation: Weltz, M.A., Spaeth, K. 2012. Estimating effects of targeted conservation on nonfederal rangelands. Rangelands. 34(4):35-40. Interpretive Summary: Modeling of soil erosion based on quantitative data from rangeland National Resources Inventory (NRI) can be used to predict the effectiveness of alternative management actions and support cost–benefit analyses to optimize return on investment in conservation. The spatially unbiased nature of the rangeland NRI assessment allows for rapid determination of regional needs and identification of where conservation may be most cost-effective in arresting land degradation and enhancing ecosystem services. This same concept can be used to inform policy and to provide a quantitative mechanism to justify targeting to meet specific goals as being cost effective. It is more cost-effective to prevent soil loss than it is to restore a site after it has been significantly degraded—if it is even possible to restore a degraded site. Therefore, effective conservation planning should incorporate risk-based assessments by using return period runoff events, which would encourage proactive conservation implementation before those events occur. Technical Abstract: On arid and semiarid rangelands, soil erosion is episodic in nature because of extremes in precipitation from year to year. Evaluation of long-term, average, annual soil loss on rangeland is inappropriate because, in many cases, water-induced soil erosion may not occur on arid or semiarid rangelands for many consecutive years to decades because of limited precipitation. However, this does not mean that rangelands are not susceptible and vulnerable to erosion. For example, in drought conditions, where vegetation production has been significantly reduced and bare ground has increased, once rainfall commences, the exposed bare soil surface is easily eroded and concentrated flow paths may form. Rangelands are not manipulated annually like row crops. Once formed, concentrated flow paths (rills or ephemeral gullies on croplands) can accelerate soil erosion and the land degradation process. On rangelands, these concentrated flow paths facilitate water accumulation and accelerated soil loss in subsequent rainfall events resulting in the site crossing a hydrologic threshold and being permanently degraded. Most of the soil loss on rangelands occurs during infrequent, intense storms that generate large amounts of runoff that scours the soil surface. Modeling of soil erosion based on quantitative data from rangeland National Resources Inventory (NRI) can be used to predict the effectiveness of alternative management actions and support cost–benefit analyses to optimize return on investment in conservation. The spatially unbiased nature of the rangeland NRI assessment allows for rapid determination of regional needs and identification of where conservation may be most cost-effective in arresting land degradation and enhancing ecosystem services. This same concept can be used to inform policy and to provide a quantitative mechanism to justify targeting to meet specific goals as being cost effective. It is more cost-effective to prevent soil loss than it is to restore a site after it has been significantly degraded—if it is even possible to restore a degraded site. Therefore, effective conservation planning should incorporate risk-based assessments by using return period runoff events, which would encourage proactive conservation implementation before those events occur. |
