Dynamics of soil meso- and microfauna communities in Zoige alpine meadows on the eastern edge of Qinghai-Tibet Plateau, China

Soil fauna play an important role in terrestrial ecosystems, directly or indirectly modulating the availability of resources for other species by changing biotic or abiotic materials. Knowledge of temporal variability of soil fauna is crucial to understanding soil community dynamics and food webs, especially in variable systems such as an alpine meadow ecosystem. A typical alpine meadow in Zoige County grassland located on the eastern edge of Qinghai-Tibet Plateau, China, was studied to document the composition, diversity, and seasonal variations of soil meso- and microfauna communities in alpine grasslands. Six 50 m x 50 m plots were established using permanent markers. Five observations were conducted from July 2008 to October 2009 and six samples in size of 50 cm x 50 cm were investigated in each plot every time. Tullgren and Baermann's methods were used to extract 9318 soil meso- and microfauna individuals and these were classified into threephyla, seven classes, and 88 taxonomic groups. The mean density of the soil meso- and microfauna community was 39941.67 ind./m super(2). Nematoda dominated, accounting for 91.50% of the individuals in the soil meso- and microfauna community; Arachnida (mainly Acarina), Collembola, Oligochaeta (mainly Enchytraeidae) and Insecta (mainly Diptera larvae and Coleoptera larvae) made up 3.73%, 2.55%, 1.12%, and 1.07%, respectively. The community individual density, taxonomic group, and diversity indexes of soil meso- and microfauna varied by season both intra- and inter-years, with minimum numbers of both individuals and taxonomic groups recorded in July and the maximum in October. Significant seasonal changes were recorded in community taxonomic groups, individual density, density-group indices, the Shannon and Pielou indices (P