Species diversity of polyporoid and corticioid fungi in northern hardwood forests with differing management histories

Abstract

Effects of forest management on fungal diversity were investigated by sampling fruit bodies of polyporoid and corticioid fungi in forest stands that have different management histories. Fruit bodies were sampled in 15 northern hardwood stands in northern Wisconsin and the upper peninsula of Michigan. Sampling was conducted in five old-growth stands, five uneven-age stands, three even-age un-thinned stands and two even-age thinned stands. Plots 100 m × 60 m were established and 3000 m2 within each plot was sampled during the summers of 1996 and 1997. A total of 255 polyporoid and corticioid morphological species were identified, 46 (≈18%) of which could not be assigned to a described species. Species accumulation curves for sites and management classes differed from straight lines, although variability from year to year suggests that more than 2 y of sampling are needed to characterize annual variation. Mean species richness and diversity index values did not vary significantly by management class, although mean richness on large diameter wood (≥ 15 cm diam) varied with moderate significance. Richness values on small diameter debris varied significantly by year, indicating that a large part of year-to-year variability in total species richness is due to small diameter debris. Ten species had abundance levels that varied by management class. Two of these species, Cystostereum murraii and Rigidoporus crocatus, were most abundant in old-growth and might be good indicators of stands with old-growth characteristics. Oxyporus populinus, an important pathogen of Acer spp., was most abundant in even-age stands. Regression analyses indicated that substrate quality (diameter and species), quantity and management history of the stand were important in predicting the number of occurrences of the five most-abundant species. Changes in the diversity and species composition of the wood-inhabiting fungal community could have significant implications for the diversity, health and productivity of forest ecosystems.