Abstract: Soil fauna maintains the stability of soil ecological structure and plays an important role in the material cycle and energy exchange of natural ecosystems. The population and quantity of soil fauna were investigated under the 5-year mimic condition of increasing precipitation (2013-2015) in Maodeng Pasture of Xilingol grassland in Inner Mongolia,China to understand the impact of precipitation change on the distribution and quantity of soil fauna population. A total of 1969 soil fauna individuals which belong to 3 phyla,5 classes and 13 groups were collected from 9 surveys in 3 years. The dominant groups were Nematodes,Coleoptera,Hymenoptera,and Acarina;the common groups were Arachnids,Hemiptera,and Tails,and the rest are rare groups. The results showed that:There was no significant effect on the species and density of soil macrofauna,and the dominant species varied slightly in different seasons,and Coleoptera and Hymenoptera were relatively stable. There was no significant effect on soil dry-type meso-and micro-fauna. There was a significant effect on soil wet-type meso-and micro-fauna (P<0.05),especially in May when the precipitation was increased by 50 mm,which was conducive to its growth. The results showed that soil macrofauna and soil dry-type meso-and micro-fauna were more tolerant to precipitation changes,while Nematodes could be an important indicator of precipitation changes.

Key words: Precipitation, Soil fauna, Grassland ecosystem, Xilingol

摘要： 为研究降水对典型草原地区土壤动物的影响，我们对内蒙古自治区锡林浩特市毛登牧场进行增加降水试验，于2013-2015年5，7和9月，对土壤动物群落进行了调查，分析了不同季节降水变化对土壤动物数量的影响。3年9次调查，共采集土壤动物1969头，分别隶属3门5纲13目。优势类群有：线虫（Nematodes）、鞘翅目（Coleoptera）、膜翅目（Hymenoptera）和蜱螨目（Acarina）；常见类群有：蜘蛛目（Arachnids）、半翅目（Hemiptera）和弹尾目（Tails），其余为稀有类群。研究发现：降水处理对大型土壤动物的种类的密度没有显著影响，不同季节中大型土壤动物的优势种略有变化，优势类群鞘翅目和膜翅目较为稳定；降水变化对中小型干生土壤动物没有显著影响；而对中小型湿生土壤动物密度的影响显著增加（P<0.05），且在5月增加降水50 mm，最有利于其生长繁殖。结果表明：大型和中小型干生土壤动物对降水变化的耐受性较强，线虫类对降水变化具有重要的指示作用。

关键词: 降水, 土壤动物, 草地生态系统, 锡林郭勒