THE EFFECTS OF THINNING AND BROADCAST BURNING ON SPOROCARP PRODUCTION OF HYPOGEOUS FUNGI

The objectives of our study were to determine the effects of commercial thinning and broadcast burning on sporocarp production of hypogeous ectomycorrhizal (HEM) fungi. At two sites in northeastern California, Jennie Springs (JS) and Swain Mountain (SM), we compared HEM sporocarp production among units that had been heavily thinned, moderately thinned, and unthinned. At one of those sites, JS, we also compared sporocarp production between units that had been broadcast burned and units left unburned. Sporocarps were sampled in 1992, 10 years after thinning and 9 years after burning occurred at JS, and 17 years after thinning occurred at SM. Total relative frequency and biomass of sporocarps did not differ significantly among thin levels at either site, or between burn levels at JS. There was, however, significant association between thin level and frequencies of the most common genera at JS, suggesting that thinning significantly affected the composition of HEM fungi. The association between burn level and frequencies of the most common genera was also significant, but less pronounced than the association between thin level and the frequencies of common genera.