Pacific Southwest Research Station

Effects of Pile Burning on Soil and Water Quality

Full title: Effects of pile burning in the Tahoe basin on soil and water quality

Lead Researchers: Ken Hubbert and Matt Busse, U.S. Forest Service, Pacific Southwest Research Station; Steve Overby, U.S. Forest Service, Rocky Mountain Research Station

Abstract

Pile burning has been adopted by most agencies to reduce fuels and fire hazard in the Tahoe basin. From 1998 to 2007, a total of 11,708 acres have been mechanically- or hand-thinned with resulting slash piled and burned. Whether this practice results in detrimental changes in soil and water quality across a significant percentage of the treated area is unclear. Concern for the ecological effects of pile burning has been raised as soil temperatures of 400°C have been measured beneath large slash piles, with significant changes in soil physical, chemical, and biological properties observed. High soil temperatures are known to kill soil organisms, seeds, and plant roots, while destroying organic matter and altering water infiltration rates and nutrient cycling. Heat-induced changes also affect soil nitrate and phosphate status and facilitate their movement in surface and subsurface flow, resulting in broad implications for lake functions, processes, and management. Guidelines for pile burn size, spacing, and distance from stream environment zones are especially needed in the Tahoe basin. This study will quantify the downward heat pulse for an assortment of pile sizes and conditions typical of Tahoe basin burning. We will monitor the resilience of key soil physical, chemical, and biological properties for a two-year period following pile burning, as well as quantify nitrate and phosphate movement in surface and subsurface runoff.