多年模拟氮沉降对华西雨屏区苦竹人工林土壤节肢动物的影响

Effects of long-term simulated nitrogen deposition on soil arthropods in a Pleioblastus amarus plantation in rainy area of western China

土壤动物在生态系统养分循环中扮演着重要角色,其中土壤节肢动物在凋落物破碎和土壤团聚体形成中起着决定性作用。为探究多年模拟氮沉降对苦竹人工林土壤节肢动物的影响,于2007年11月起在华西雨屏区苦竹人工林进行了每月1次的模拟氮沉降试验,以硝酸铵为氮源,设对照(0 g N·m^(-2)·a^(-1))、低氮(5 g N·m^(-2)·a^(-1))、中氮(15 g N·m^(-2)·a^(-1))和高氮(30 g N·m^(-2)·a^(-1)) 4个处理。在施氮6.5年后分别于2014年1月、10月,2015年1月采集凋落物层和0～15 cm土层样品带回实验室分离鉴定。结果显示:本试验共观察到土壤节肢动物1852只,隶属于3门7纲18目;凋落物层土壤节肢动物个体数和类群数随施氮浓度的升高而增加,且高氮处理显著高于对照;土壤层土壤节肢动物个体数和类群数随施氮浓度的升高而减少,但与对照相比均不显著;模拟氮沉降对凋落物层和土壤层土壤节肢动物多样性指数、均匀度指数和丰富度指数均无显著影响。

Soil fauna plays an important role in ecosystem nutrient cycling.Soil arthropods play a fundamental role in litter breaking process and in the formation of soil aggregates.We examined the effects of chronic N deposition on soil arthropod communities in a Pleioblastus amarus plantation in the rainy area of west China,with a field experiment involving monthly simulated N deposition using NH4 NO3 since 2007.There were four levels of N addition:control(0 g N·m-2·a-1),low N(5 g N·m-2·a-1),medium N(15 g N·m-2·a-1)and high N(30 g N·m-2·a-1).After six and half years of treatment,litter of P.amarus and soil samples were collected in January 2014,October 2014 and January 2015.The results showed that 1852 individuals of soil arthropods were found,which could be classified into 3 phyla,7 classes and 18 orders.The individuals and species number of soil arthropods increased with increasing N deposition levels in the litter layer,being significantly higher in the high N treatment than that in control.In the soil layer,the individuals and species number of soil arthropods decreased with increasing N deposition levels,although there was no significant difference among the different treatments.Simulated N deposition had no significant effects on the Shannon diversity,Pielou evenness,and Menhinick richness indices of soil arthropods in both litter layer and soil layer.