U.S. Joint Fire Science Program


Date of this Version


Document Type



Final Report: JFSP Project Number 05-2-1-87


US government work.


The purpose of this study was to examine the effects of mechanical mastication followed by prescribed fire on mycorrhizal fungi and hypogeous sporocarps. A dense fire-prone mixed hardwood-conifer chaparral comprises a significant component of vegetation at Whiskeytown National Recreation Area. Prescribed burns, as fuel reduction treatments, are limited by air quality restrictions and narrow climatic conditions appropriate for burnings. Brush mastication is a fast and inexpensive tool commonly used by land managers to reduce ladder fuels. However, a dense layer of chipped debris remains, which, when burned, heats the soil more than ladder fuels. The upper layers of mineral soil contain roots of woody plants that form mycorrhizas, symbiotic associations of fungi and roots. The effects of the thick layer of slash created from brush mastication on mycorrhizas are unknown. Changes may occur in the community of mycorrhizal fungi, and in the fungal sporocarps produced belowground. Treatments included mechanical mastication, mechanical mastication followed by prescribed fire, prescribed fire only, and untreated controls. For mycorrhizas, soil samples were taken at the canopy dripline of ectomycorrhizal trees. Mycorrhizas were described by morphology and by DNA sequences of the ITS region. Hypogeous fungi were sampled by scuffling. Mycorrhizal communities were highly similar in all treatments with no particular changes due to mastication and burning. However, hypogeous sporocarps were greatly reduced by burning, either of standing chaparral or masticated vegetation. We conclude that prescribed burning of mechanically masticated slash does not harm mycorrhizal communities, but does inhibit fruiting of hypogeous fungi.