Functional relationships between soil fungi and environment in alpine tundra

Abstract

Temperature, moisture, available potassium, and soil pH were the most important abiotic variables influencing the distribution and community composition of soil fungi from three diverse alpine habitats. The major differences in species composition occurred among the sites. An ordination contrasting the sites, based on the species composition of the mycoflora, was correlated with a gradient contrasting temperature and moisture with potassium. The observed differences in species composition among the sites were concluded to have resulted from conflicting demands on the species for efficiency and adaptability. Relatively few species were isolated from the more exposed summit ridge site (2840 m). and these were probably genetically diverse species capable of adapting to environmental extremes. Alternatively, dominant species may be specialists adapted to limiting dimensions that are widely distributed in the environment. Dominant species at the drought-prone grassland site (1900 m) appeared adapted to low moisture, and those of the alpine meadow site (2530 m) to low temperature.Seasonal changes in mycoflora composition were related to changes in the moisture and temperature status of the soils, with low temperature limiting in the spring and low moisture in the fall. Chrysosporium pannorum and Penieillium janthinellum were adapted to combined low temperature and moisture. Cylindroearpon didymuin, Glioeladium deliquescens, Fusarium merismoides. Penicillium steckii, and Cylindrocarpon destructans occurred only in soils with a relatively high temperature–moisture status. Changes in mycoflora composition with soil depth were attributed to an environmental gradient combining temperature, moisture, and K without contrasts. Sterile fungi, apparently adapted to the adverse conditions of low temperature. moisture, and K. were dominant in the lower horizons at all three sites. Soil K appeared to be a limiting factor for many species restricted to the surface horizons, including the frequently isolated species Fusarium acuminatum. Penicillium janthinellum. Penicillium simplicissimum. Penicillium steckii. Phoma eupyrena. and Trichoderma liamatum.