CAZARES, EFREN1, DAN L. LUOMA1, JOYCE EBERHART1, MICHAEL P. AMARANTHUS2, CAITLIN CRAY3, JOHN DODD3 & MICHAEL McARTHUR3.
1Dept. of Forest Science, Oregon State University, Corvallis, OR, 97331-7501, U.S.A. 2 USDA. Forest Service, Pacific Northwest Research Station, Box 440 Grants Pass, OR, 97526, U.S.A. 3 USDA. Mt. Hood National Forest, Dufur Ranger Station, Box 67, Dufur, OR, 97021, U.S.A.
Diversity and biomass of hypogeous ectomycorrhizal fungi were monitored after salvage logging in two forest stands on Mt. Hood National Forest, Oregon, USA. One stand (Silver 1) consists of Abies grandis, Pseudotsuga menziesii, Pinus ponderosa, P. contorta and Larix occidentalis. The other (Silver 8) consists of P. ponderosa, P. menziesii and A. grandis. In all, 768 four-m2 plots were searched for truffles in uncompacted soil (control), compacted, and ripped treatment areas during spring and fall since 1995. In uncompacted areas of Silver 1, diversity and biomass increased 1 year after disturbance, but 2 years later both decreased. Compacted areas initially decreased in diversity and biomass and remained low 3 years after being logged. Ripped areas decreased in diversity and biomass initially but are rebounding 3 years after treatment; they are still lower than uncompacted areas. In Silver 8, truffle diversity did not change for 3 years following disturbance in uncompacted areas, but biomass varied between years. Compacted areas remain low in diversity and biomass 3 years after treatment. Ripped areas initially decreased in diversity and biomass but are recovering during the third year; biomass and diversity remain lower than in uncompacted areas. Total diversity and biomass were higher in the uncompacted areas than compacted and ripped areas in both Silver 1 and 8 stands during the first three years after treatment. However, diversity and biomass fluctuated seasonally in both stands. This monitoring effort will continue during the next two years.