干旱区生态环境知识资源中心

A systematic survey for myxomycetes in winter-cold deserts and steppes of western Mongolia resulted in a total of 333 records belonging to 36 species from 13 genera and 7 families. Physarum notabile as the most common species was recorded 72 times, but about one third of all species was classified as rare for the whole study area. Due to the very arid climate of the region, all specimens were obtained by applying the moist chamber culture technique. Maximum values for diversity and species richness were recorded in dry steppe/shrub and mountain steppe/tall shrub communities. whereas extrazonal grasslands and alpine steppes had the most depauperate myxomycete biota. Among three different groups of substrata (bark of shrubs, ground litter, and dung of herbivores) diverging trends in species richness and substrate specificity of the species were found: bark had the richest but least specific, dung the poorest but most specific myxomycete assemblage. A hierarchical cluster analysis carried out on the incidence-based Chao-Soerensen index clearly indicates a separation between myxomycete biotas of Eurasian, western North American and South American deserts, supporting the moderate endemieity model postulated for various other groups of microbes and protists.