高寒湿地土壤微生物区系组成对氮添加的响应

Response of microbial flora to nitrogen addition in alpine wetlands

土壤微生物是土壤养分循环的关键驱动者,对土壤环境变化感应明显,氮是陆地生态系统的限制元素之一,其改变可能会给生态系统物种多样性造成一定影响。为了解高寒湿地土壤微生物组成对氮添加的响应,以青海湖流域高寒湿地为研究对象,通过(0 g·m^(-2)、0.5 g·m^(-2)、1 g·m^(-2)、1.5 g·m^(-2)、2 g·m^(-2)、2.5 g·m^(-2)、5 g·m^(-2)、10 g·m^(-2))8个水平的模拟氮添加试验,采用高通量测序技术,分析土壤微生物区系组成对氮添加的响应。结果表明:氮添加使细菌、真菌和古菌的Chao1指数均下降,细菌和古菌的Shannon指数显著增加(P<0.05),真菌Shannon指数显著下降(P<0.05);氮沉降改变微生物群落结构,变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、广古菌门(Euryarchaeota)和泉古菌门(Crenarchaeota)的相对丰度均减少,而酸杆菌门(Acidobacteria)和子囊菌门(Ascomycota)的相对丰度增加;真菌群落对于氮添加的响应变化较低,对环境的适应性可能要优于细菌和古菌群落。由此可见,氮添加对不同土壤微生物的影响存在一定差异,氮沉降是不断积累的过程,长时间的氮沉降势必会引起土壤微生物群落的改变,影响生态系统的稳定。

Soil microorganisms are the key drivers of soil nutrient cycle and have obvious induction to soil environmental change.Nitrogen is one of the limiting elements of terrestrial ecosystem,and its change may have a certain impact on the species diversity of the ecosystem.In order to understand the response of soil microbial composition to nitrogen addition in alpine wetland of Qinghai Lake Basin,eight levels of simulated nitrogen addition tests were conducted(0 g·m^(-2),0.5 g·m^(-2),1 g·m^(-2),1.5 g·m^(-2),2 g·m^(-2),2.5 g·m^(-2),5 g·m^(-2),10 g·m^(-2)).The results showed that nitrogen addition reduced the Chao1 index of bacterial fungi and archaea,and the Shannon index of bacteria and archaea increased significantly(P<0.05).The Shannon index of fungi decreased significantly(P<0.05).The nitrogen deposition changed the microbial community structure,and the relative abundance of Proteobacteria,Actinobacteria,Euryarchaeota and Crenarchaeota decreased,while that of Acidobacteria and Ascomycota increased.Fungal communities have a low response to nitrogen addition and may be more adaptive to the environment than bacterial and archaea communities.These results indicate that the effects of nitrogen addition on different soil microorganisms are different.Nitrogen deposition is a process of continuous accumulation,and long-term nitrogen deposition is bound to cause changes in soil microbial community and affect the stability of the ecosystem.