氮添加对亚热带毛竹林土壤微生物群落结构的影响

氮沉降会影响森林生态系统地上(如植物生产力和组成)和地下特性(如土壤养分循环),进而影响土壤微生物群落结构和功能。本研究以亚热带戴云山毛竹林为对象,设置N0(0 kg N·hm^-2·a^-1)、N20(20 kg N·hm^-2·a^-1)、N80(80 kg N·hm^-2·a^-1) 3个施氮水平,进行3年的氮沉降模拟实验。通过测定土壤基本理化性质、腐殖化指数和微生物磷脂脂肪酸等指标,研究氮添加对毛竹林土壤养分、腐殖化指数和微生物群落结构的影响。结果显示,N20显著增加土壤腐殖化指数,降低土壤中碱性阳离子总量(K⁺,Na⁺,Ca²⁺,Mg²⁺)、革兰氏阳性菌(G⁺)、革兰氏阴性菌(G^-)、总磷脂脂肪酸含量和G⁺/G^-。与N20相比,N80处理土壤NO₃^-

Effects of nitrogen addition on soil microbial community structure in a subtropical Phyllostachy pubescens forest

Nitrogen deposition affects aboveground(such as plant productivity and composition)and belowground properties(such as soil nutrient cycling)in forest ecosystems,with consequences on the structure and function of soil microbial community.We simulated nitrogen deposition at three levels[N0(0 kg N·hm^-2·a^-1),N20(20 kg N·hm^-2·a^-1),N80(80 kg N·m^-2·a^-1)]in a Phyllostachy pubescens forest in Daiyun Mountain in subtropical China for three years.We measured soil physicochemical properties,humification index,and microbial phospholipid fatty acids to clarify how nitrogen addition affects soil nutrients and microbial community structure in P.pubescens forest.The results showed that N20 treatment significantly increased soil humification index,reduced total content of alkaline cations(K^+,Na^+,Ca^2+,Mg^2+),Grampositive bacteria(G^+),Gram-negative bacteria(G^-),total phospholipid fatty acids(total PLFAs),and the ratio of G^+/G^-.Compared to N20 treatment,N80 treatment significantly increased the contents of soil nitrate,G^+,G^-,total PLFAs and G^+/G^-(P<0.05).Results of correlation analysis showed that soil humification index was negatively correlated with soil microbial biomass.Results of redundancy analysis showed that the total amount of alkaline cations and available nitrogen were important environmental factors driving the changes of microbial community structure.Our results indicated that nitrogen addition may change soil microbial nutrient requirements in the P.pubescens forest,which in turn affects soil microbial community structure.