Responses of soil insect communities to alpine wetland degradation on the eastern Qinghai-Tibetan Plateau, China

The wetlands on Earth are under different levels of degradation, and over half of them have even been lost during the 20th century. However, the response of soil insect communities to alpine wetland degradation is unknown, particularly in the Zoigê wetland, which spanning northern Sichuan, southern Gansu and Qinghai Provinces of China. Four habitats, including wet meadows, grassland meadows, moderately degraded meadows and severely degraded meadows, were selected in the Zoigê wetland, and the soil insect communities, plant communities and soil properties were investigated from April 2009 to October 2011. Diptera larvae and Coleoptera were the most abundant taxa. The soil insect taxonomic composition in the severely degraded meadows was clearly different from these of the others. The soil insect abundance significantly increased in the grassland meadows and declined in the severely degraded meadows. Similar response was found for the abundance of the Diptera larvae. The taxonomic richness and diversity of the soil insect community declined significantly in the severely degraded meadows, as well as the abundances of Coleoptera larvae and adults. The plant community and soil physicochemical properties together determined the spatial distributions of the soil insect communities, and the available soil P and K and vegetation height were the main factors that determined the abundances and diversities of the soil insect communities. Our observations demonstrated that the soil insect communities were sensitive to alpine wetland degradation, which suggests that there are drastic changes in ecological function during wetland degradation.