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ARS Home » Pacific West Area » Reno, Nevada » Great Basin Rangelands Research » Research » Publications at this Location » Publication #322972

Title: Woody Plant Encroachment and Effects on Soil Health

item Weltz, Mark
item SPAETH, KENNETH - Natural Resources Conservation Service (NRCS, USDA)
item NOUWAKPO, SANJRO - University Of Nevada

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/31/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only.

Technical Abstract: Sustainability of range plant communities is in-part determined by the proper function and condition of the soil. In rangeland plant communities that have been encroached by woodland species (e.g., Pinyon pine and Juniper) soil erosion rates can be significantly increased. Understory vegetation is often reduced in the interspaces between trees due to competition. This provides a feedback loop in that bare soil is increased resulting in increased raindrop splash erosion and concentration of runoff in the interspaces as hydraulic roughness is lower due to lack of herbaceous plants and litter in the interspace. This combined affect results in significant removal of soil and nutrients offsite through accelerated soil erosion processes. Once initiated these concentrated flow paths (rills) remain intact and deepen with each succeeding runoff event if the encroaching tress are not removed and replace with appropriate shrub and herbaceous vegetation. Sustainability and soil health is compromised in this situation as once a significant amount of soil is removed the capacity of the site to provide goods and services is diminished in perpetuity. The end result is a development of an alternative ecological state with diminished capacity for goods and services. Rangeland communities are further influenced by episodic disturbances such as drought and fire. The most-developed quantitative indicators of conservation effects currently on rangelands are 1) modeled soil erosion, and 2) the density and types of invasive plant species. Current technology to estimate soil erosion on upland rangelands with the Rangeland Hydrology and Erosion Model and potential thresholds of soil erosion that will have negative impacts on soil health as a result of woody plant encroachment, invasive species, and fire will be presented and discussed. Benefits of conservation to reduce or prevent soil loss and reduction in soil health will be discussed using examples from Pinyon-Juniper woodlands and Oak Savannahs.