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United States Department of Agriculture

Agricultural Research Service

Research Project: DISTURBANCE ASSESSMENT AND MITIGATION OF GREAT BASIN RANGELAND

Location: Northwest Watershed Management Research

Title: Vegetation and groundcover influences on hydrology and erosion in pinyon and juniper woodland communities

Authors
item Pierson, Frederick
item Kormos, Patrick
item Williams, Christopher

Submitted to: International Soil and Water Conservation Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 17, 2008
Publication Date: May 18, 2008
Citation: Pierson Jr, F.B., Kormos, P.R., Williams, C.J. 2008. Vegetation and Groundcover Influences on Hydrology and Erosion in Pinyon and Juniper Woodland Communities. In:15th International Congress of the International Soil and Water Conservation Organization Book of Abstracts, May 18-23,2008, Budapest-Hungary.

Interpretive Summary: Pinyon (Pinus spp.) and juniper (Juniperus spp.) woodlands have expanded 10-fold in the last 130 years and now occupy nearly 20 million ha of sagebrush (Artemisia spp.) shrub steppe in the Great Basin Region and Colorado Plateau, USA. The conversion of sagebrush steppe to pinyon and juniper woodlands has been linked to reduced forage production, altered wildlife habitat, changes in plant community structure and composition, and increased overland flow and erosion from these landscapes. The Sagebrush Steppe Treatment Evaluation Project (SageSTEP, www.sagestep.org) was implemented in 2005 as a 5 year interdisciplinary research study to evaluate restoration methodologies for sagebrush rangelands degraded by woodland and grassland encroachment over a six state area within the Great Basin. The hydrology discipline of SageSTEP focuses on the relationships between changes in vegetation and groundcover and runoff/erosion processes. Rainfall simulation over small (0.5 m2) and large (14 m2) plot scales and concentrated flow experiments were applied across a gradient of canopy and ground cover to determine whether critical thresholds exist in vegetation and ground cover that significantly influence infiltration, runoff, and erosion in pinyon and juniper woodlands. Water drop penetration times and wetting front spatial patterns were used to investigate the influence of soil water repellency on infiltration rates across the vegetative gradient. Results from this study provide a dataset for comparison with runoff and erosion following future sagebrush steppe restoration treatments in the SageSTEP study.

Technical Abstract: Pinyon (Pinus spp.) and juniper (Juniperus spp.) woodlands have expanded 10-fold in the last 130 years and now occupy nearly 20 million ha of sagebrush (Artemisia spp.) shrub steppe in the Great Basin Region and Colorado Plateau, USA. The conversion of sagebrush steppe to pinyon and juniper woodlands has been linked to reduced forage production, altered wildlife habitat, changes in plant community structure and composition, and increased overland flow and erosion from these landscapes. The Sagebrush Steppe Treatment Evaluation Project (SageSTEP, www.sagestep.org) was implemented in 2005 as a 5 year interdisciplinary research study to evaluate restoration methodologies for sagebrush rangelands degraded by woodland and grassland encroachment over a six state area within the Great Basin. The hydrology discipline of SageSTEP focuses on the relationships between changes in vegetation and groundcover and runoff/erosion processes. Rainfall simulation over small (0.5 m2) and large (14 m2) plot scales and concentrated flow experiments were applied across a gradient of canopy and ground cover to determine whether critical thresholds exist in vegetation and ground cover that significantly influence infiltration, runoff, and erosion in pinyon and juniper woodlands. Water drop penetration times and wetting front spatial patterns were used to investigate the influence of soil water repellency on infiltration rates across the vegetative gradient. Results from this study provide a dataset for comparison with runoff and erosion following future sagebrush steppe restoration treatments in the SageSTEP study.

Last Modified: 10/1/2014
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