三江平原土壤动物群落多样性对CO_2浓度升高的响应

The response of diverse soil fauna communities to elevated CO_2 concentrations in Sanjiang Plain

为研究大气CO_2浓度升高条件下土壤动物的响应,本文采用开顶式气室(OTC)控制大气CO_2浓度,设置了3个梯度,分别为低浓度370 ppm背景CO_2 (AC)、中浓度550 ppm CO_2 (EC1)和高浓度700 ppm CO_2 (EC2)。于2017年秋季取样并用改良Tullgren干漏斗法和Baermann湿漏斗分离土壤动物。结果表明:(1)共捕获土壤动物6,268头,隶属于7纲15目,优势类群为甲螨亚目,占捕获量的88.13%;常见类群为弹尾目和双翅目幼虫,合计占捕获量的9%。不同CO_2浓度水平下,优势类群(甲螨亚目)和常见类群(弹尾目、双翅目幼虫)相同,但是稀有类群存在一定差异。(2)CO_2浓度升高显著增加了甲螨亚目的类群数和个体密度,显著降低了弹尾目的类群数和个体密度,对其他土壤动物无显著影响。(3)三江平原不同浓度条件下土壤动物的Shannon-Wiener多样性指数、Pielou均匀度指数均为AC>EC1> EC2,而优势度指数为EC2> EC1> AC,丰富度指数为AC> EC2> EC1。研究表明,气候变化有可能影响土壤动物的群落结构以及土壤动物的多样性。

The effect of elevated atmospheric CO2 concentrations was investigated on soil fauna communities, controlling the concentrations at 370, 550 and 700 ppm in open top chambers in Sanjiang Plain. Samples were taken and separated by Tullgren or Baermann funnel methods in autumn 2017. Our results showed that：（1） 6,268 individuals belonging to seven classes and 15 orders were collected. Oribatida was the dominant group, accounting for 88.13% of the total individuals. Collembola and Diptera larvae were the other most common groups, accounting for 9% in total, respectively. Different groups varied in their responses to elevated CO2 concentrations. Oribatida was the dominant group. Collembola and Diptera larvae were the most common groups in AC, EC1 and EC2, but rare groups also differed in AC, EC1 and EC2.（2） The elevated CO2 concentration significantly increased the density of Oribatida, but reduced the density of Collembola. However, no other soil fauna were significantly affected.（3） The Shannon-Wiener index and the Pielou index of soil fauna exhibited the order of AC EC1 EC2, the Simpson index showed the order of EC2 EC1 AC, and the Margalef index showed the order of AC EC2 EC1. Our results indicate that the soil fauna community composition and diversity might be affected by climate change.