Ecohydrological controls on soil moisture and hydraulic conductivity within a pinyon-juniper woodland

I. Lebron, M. D. Madsen, D. G. Chandler, D. A. Robinson, O. Wendroth, J. Belnap

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

The impact of pinyon-juniper woodland encroachment on rangeland ecosystems is often associated with a reduction of streamflow and recharge and an increase in soil erosion. The objective of this study is to investigate vegetational control on seasonal soil hydrologic properties along a 15-m transect in pinyon-juniper woodland with biocrust. We demonstrate that the juniper tree controls soil water content (SWC) patterns directly under the canopy via interception, and beyond the canopy via shading in a preferred orientation, opposite to the prevailing wind direction. The juniper also controls the SWC and unsaturated hydraulic conductivity measured close to water saturation (K(h)) under the canopy by the creation of soil water repellency due to needle drop. We use this information to refine the hydrologic functional unit (HFU) concept into three interacting hydrologic units: canopy patches, intercanopy patches, and a transitional unit formed by intercanopy patches in the rain shadow of the juniper tree. Spatial autoregressive state-space models show the close relationship between K(h) close to soil water saturation and SWC at medium and low levels, integrating a number of influences on hydraulic conductivity.

Original languageEnglish (US)
Article numberW08422
JournalWater Resources Research
Volume43
Issue number8
DOIs
StatePublished - Aug 1 2007
Externally publishedYes

ASJC Scopus subject areas

  • Water Science and Technology

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