高寒草甸退化对土壤昆虫多样性的影响

Effects of alpine meadow degradation on soil insect diversity in the Qinghai-Tibetan Plateau

土壤昆虫是陆地生态系统的重要组成部分,在物质循环和能量转化过程中起着重要的作用。为了查明高寒草甸生态系统退化对土壤昆虫群落的影响,于2011年的4、5、7和10月份别对青藏东缘的若尔盖高寒草甸的沼泽草甸、草原草甸、中度退化草甸和重度退化草甸的土壤昆虫群落进行了调查。共捕获土壤昆虫4172只,隶属于8目35科,共46类。优势类群有尖眼蕈蚊科幼虫(Sciaridae larvae)、摇蚊科幼虫(Chironomidae larvae)和象甲科幼虫(Curculionidae larvae),其中尖眼蕈蚊科幼虫为各退化阶段的共同优势类群。重度退化草甸的土壤昆虫密度和多样性指数均显著低于其它退化阶段(P<0.01)。各退化阶段间的Sorenson相似性和Morisita-Horn相似性指数变化趋势表明退化对土壤昆虫的类群组和优势类群的个体数量影响较大。而土壤昆虫的群落密度和多样性指数的季节动态在不同退化阶段间也存在差异。此外,高寒草甸的退化还可影响昆虫群落优势类群的时空分布,但不同类群间存在差异。相关分析结果表明土壤昆虫多样性与土壤p H值呈显著负相关(P<0.01),与地下生物量和磷含量呈显著正相关(P<0.01),而密度仅与p H值呈显著负相关(P<0.01)。研究结果表明高寒草甸退化可通过改变植物群落及土壤等环境因子影响土壤昆虫群落组成和多样性的空间分布和季节动态。

Soil insects are an important component and play a key role in the material cycling and energy flow grassland ecosys Qinghai-Tibetan tems. However, soil insect populations are easily influenced by changes in environmental Plateau is the highest and largest vegetation. Alpine meadow degradation has become processes in factors. The plateau in the world, and is mainly dominated by alpine meadow an important, widespread, and growing ecological problem in the Qinghai-Tibetan Plateau due to the effects of climate change and increasing overgrazing. The Zoig8 wetland, which is located on the eastern edge of the Qinghai-Tibetan Plateau, has also degraded due to climate change and increased overgrazing over the last 50 years. Currently, there are four typical habitats （swamp meadow, grassland meadow, moderately degraded meadow, and seriously degraded meadow） in this area. However, the changes in the structure and each habitat to investigate the effects of alpine meadow degradation on the soil insect community in April, May, July, and October of 2011. A total of 4,172 insect individuals were captured and classified into 8 orders, 35 families, and 46 taxonomic groups. The Sciaridae larvae, Chironomidae larvae, and Curculionidae larvae were the dominant groups in soil insect communities, and Sciaridae larvae comprised the most dominant group at all four degradation phases. The density and diversity indices of the soil insects were significantly lower in the seriously degraded meadow compared with the other degradation phases （P 〈 0.01 ）. The Sorenson and Morisita-Horn similarity indices in the different degradation stages indicated that degradation of the alpine meadow had a strong effect on the taxonomic composition and dominant group abundances of soil insect communities. Moreover, the seasonal dynamics in the density and diversity of soil insect communities also differed among the different degradation stages. Degradation of the alpine meadow also changed the spatio- temporal distributions of the dominant taxonomic groups of soil insect communities. Correlation analysis showed that the diversity indices of soil insect communities were negatively correlated to soil pH （P 〈 0.01 ） and were positively correlated to below-ground biomass and phosphorus contents （P 〈 0.01 ）, while the community density was only negatively correlated to soil pH （P 〈 0.01 ）. Our results indicated that degradation of the alpine meadow influenced the taxonomic composition and spatio-temporal distributions of the soil insect communities by altering plant communities and soil properties.