Soil microbial phosphorus turnover and identity of algae and fungi in biological soil crusts along a transect in a glacier foreland

Abstract

Although biological soil crusts (BSCs) are known for a variety of ecological functions, the role of individual biocrust organism species in BSCs on their P cycling is almost unknown. To evaluate the hypothesis that the contribution of defined cultivable taxa of fungi and algea might influence the microbial P storage and mobilization in the underlying soil, a transect was investigated in a glacier foreland in the mountain plateau Hardangervidda in Southern Norway. Microbial biomass P storage in soil under BSC increased continuously with increasing distance to the glacier and increasing fungal species richness. Lowest soil phosphatase activity and soil organic matter content were linked with highest number of algal and fungal in the overlaying BSCs. Enhanced soil microbial biomass P was linked with an increasing water content and decreasing pHCaCl2 of the soil. Nine to 21 algal and 5 to 10 fungal taxa were identified per test site from BSCs along the transect. Members of the Eustigmatophyceae and Xanthophyceae were observed exclusively close to the glacier, those of Klebsormidiophyceae exclusively in larger distance. The most common fungal genera in the BSCs were Lecythophora, Penicillium, Rhizoscyphus and Pholiota, whereas Cosmospora sp., Thelebolus globosus and Mucor hiemalis were found exclusively close to the glacier. The presence of usually biomass-rich taxa in the soil crusts was related to an increased microbial P storage in total. An increasing impact of microbial P storage under BSCs on the subsequent successional vegetation development is suggested.