Hydrologic Response of a Central Nevada Pinyon-Juniper Woodland to Prescribed Fire

Abstract

This study was conducted to determine the effect of prescribed fire on surface hydrology in Great Basin pinyon-juniper (Pinus monophylla Torr. & Frém.—Juniperus osteosperma Torr.) woodlands. Infiltration rates were measured using a single ring infiltrometer over an elevation gradient (2 103, 2 225, and 2 347 m) at 3 microsites (tree canopy, shrub canopy, and interspace) and 2 tree cover types (intermediate and high) in August 2001, before a spring prescribed burn conducted in May 2002, and then following the prescribed burn in August 2002. Infiltration experiments were used to calculate saturated hydraulic conductivity (K[ϴs]) rates, and water drop penetration times were determined to evaluate the development of water-repellent soils. Infiltration rates before the burn were greater at the low elevation than at the mid and high-elevation study sites because of differences in measured soil texture. Before burning, the infiltration and saturated hydraulic conductivity (K[ϴs]) rates measured on interspace and shrub canopy microsites were less than on tree canopy microsites at the midelevation study site (2 225 m). Following burning, the intermediate tree cover tree canopy microsites had greater infiltration rates than interspace microsites; all other microsites were similar to each other. No significant differences in K(hs) rates existed among the microsites after burning. However, on the higher elevation study site before the burn, the interspace microsites had final infiltration rates less than the tree canopy microsites, and burning caused no deviation from this trend. Saturated hydraulic conductivity rates at the high elevation did not differ by microsite before the burn, but after burning interspace microsites had K(ϴs) rates less than tree canopy microsites. Burning increased water repellency of surface soils (0-3 cm) for all cover types. Spring burning in Pinyon-juniper woodlands may produce a hydrologic response depending on surface soil texture and vegetation cover.