The diversity of litter-decomposing fungi in riparian Sitka spruce forests

Natural riparian habitats are among the most diverse, productive, and structurally complex of terrestrial habitats. Although litter-decomposing fungi are integral components of riparian habitats, they are often omitted in studies of riparian ecology and biodiversity. The purpose of this study was to determine whether riparian and upland habitats in Sitka spruce forests differed in the diversity and composition of humicolous saprophytic fungi. Sixteen (4 x 8 m) quadrates were established in both habitats at two replicate study sites. Twelve of the 16 quadrates in each habitat per site were randomly selected each sampling time. Selected quadrates were scrutinized for sporocarps of saprophytic macrofungi and taxa were recorded as present or absent. Soil moisture and temperature were sampled three times during the study, and the slope, aspect, canopy cover, substrate and vegetation covers were measured once. Diversity indices (Dmg, H', E, and 1/d), dominance-diversity curves, and the Sorensen similarity index were used to compare habitats and sites. Logistic regression was used to determine whether saprophyte taxa and environmental variables were associated with habitat or site. Results show that the riparian habitat contains greater diversity and frequency of saprophytic fungi. The habitats are most dissimilar during the dry season when the riparian soil moisture levels exceed those of the upland habitat. Clavaria rugosa, Fayodia gracilipes, Mycena tenax, and Naucoria escharoides are associated with riparian habitats and M. aurantiimarginata and M galopus are associated with the upland habitat.