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

The objectives of our study were to determine the effects of commercia l 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 thin ned, and unthinned. At one of those sites, JS, we also compared sporoc arp production between units that had been broadcast burned and units left unburned. Sporocarps were sampled in 1992, 10 years after thinnin g and 9 years after burning occurred at JS, and 17 years after thinnin g occurred at SM. Total relative frequency and biomass of sporocarps d id not differ significantly among thin levels at either site, or betwe en burn levels at JS. There was, however, significant association betw een thin level and frequencies of the most common genera at JS, sugges ting that thinning significantly affected the composition of HEM fungi . The association between burn level and frequencies of the most commo n genera was also significant, but less pronounced than the associatio n between thin level and the frequencies of common genera.