The distribution of fungi in some alpine soils

Abstract

Comparisons were made of the soil fungi isolated from three diverse alpine sites. The sites studied were a grass slope (Bromus association) at 1900 m, an alpine meadow (Dryas association) at 2530 m, and a summit ridge (Oxytropis association) at 2840 m. The effects of season, soil depth, and substrate type on the distribution of fungi were also examined. In a principal component analysis, most of the variation in mycoflora composition was attributed to differences among the sites. All taxa tested using a factorial analysis of variance showed significant differences in isolation frequency among the three sites. About half showed significant variation with season. For total fungi, the effect of seasonal change was the smallest of the four factors studied. Seasonal changes were not unidirectional, instead the composition of the fungal community shifted to one extreme in summer, with the direction of this change later reversing to another extreme in the fall opposite to that of the summer. The frequency of occurrence of most taxa was inversely related to soil depth. However, Chrysosporium pannormn, Penicillium restrictum. Penicillium canescens, and sterile fungi showed the opposite trend.The fungal communities were characterized by a few frequently isolated species, and a much larger proportion of infrequently isolated forms. All the dominant species were also widely distributed in temperate soils. The less frequently isolated species were usually highly aggregated in their distribution, with localized densities often exceeding those of the most frequently isolated forms. This pattern of distribution may have resulted from specialization on a niche dimension that was not widely distributed in the soils studied. Dominant species were less aggregated and more widely distributed, possibly reflecting a broad or diverse niche space for these species.