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United States Department of Agriculture

Agricultural Research Service

Research Project: RANGELAND RESTORATION AND MANAGEMENT Title: Soil water repellency within a burned pinon-juniper woodland: spatial distribution, severity, and ecohydrologic implications

Authors
item Madsen, Matthew
item Zvirzdin, D -
item Petersen, S -
item Hopkins, B -
item Roundy, B -
item Chandler, D -

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 18, 2011
Publication Date: July 1, 2011
Repository URL: http://hdl.handle.net/10113/50010
Citation: Madsen, M.D., Zvirzdin, D., Petersen, S., Hopkins, B., Roundy, B.A., Chandler, D. 2011. Soil water repellency within a burned pinon-juniper woodland: spatial distribution, severity, and ecohydrologic implications. Soil Science Society of America Journal. 75:1543-1553.

Interpretive Summary: Sites dominated by piñon and juniper species are often reseeded with desired native and introduced species in order to restore ecosystem function, and prevent weed invasion of annual grasses and forbs. However, for sites encroached with piñon and juniper species reseeding success can be limited. Soil water repellency is a common condition in these ecosystems that may limit site recovery. The purpose of this study was to examine the extent, and severity of soil water repellency in a burned piñon-juniper woodland, and to correlate results with soil water content, infiltration, and vegetation recovery. Research was conducted over a two year period. Measurements were performed along radial line transects that extended from the trunk of burned juniper trees to twice the canopy radius. Results were exported into a GIS-based model and used in conjunction with remotely sensed imagery to estimate the spatial distribution of soil water repellency at the landscape scale. Findings from this study indicate that post-fire patterns of soil water repellency were extensive, and positively correlated with pre-fire tree canopy cover. Where water repellency was present, infiltration rate, soil moisture, and vegetation cover and density were significantly reduced, relative to non-water repellent sites. Because of the strong correlation between post-fire tree cover and soil water repellency, this study further shows that field measurements can be extrapolated to the landscape scale, using remotely sensed imagery and GIS.

Technical Abstract: Post-fire recovery of juniper-dominated ecosystems is dependent on the extent that ecological processes have been altered. Soil water repellency is a common condition in these ecosystems that may limit site recovery. In this study we examined the extent, severity, and ecohydrologic implications of post-fire soil water repellency in a burned piñon-juniper (Pinus-Juniperus) woodland. Over a two year period, several fine-scale measurements were performed along radial line transects from the trunk of burned juniper trees to twice the canopy radius. Measurements included: soil water repellency depth and severity, soil water content, and unsaturated hydraulic conductivity measured using water and a surfactant solution. Results were exported into a GIS-based model and used in conjunction with remotely sensed imagery to estimate the spatial distribution of soil water repellency at the landscape scale. Results indicate that post-fire patterns of soil water repellency are highly correlated with pre-fire tree canopy cover; critical water repellency extended from the base of the tree to just beyond the canopy edge, while sub-critical water repellency extended half a canopy radius past the edge of the critical water repellency zone. At sites where critical soil water repellency was present, infiltration rate, soil moisture, and vegetation cover and density were significantly reduced, relative to non-water repellent sites. These variables were also reduced in soils with sub-critical water repellency (albeit to a lesser extent). This research demonstrates that GIS and remotely sensed imagery, combined with field-based spatial measurements, can be effectively used to model water repellency at the landscape scale.

Last Modified: 10/24/2014
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