增温和增氮对天津滨海湿地芦苇凋落物分解微生物群落组成和多样性的影响

Effects of warming and nitrogen input increase on composition and diversity of decomposing microbial communities of Phragmites australis litter in Tianjin coastal wetland

为了探究全球变暖和氮输入增加对滨海湿地植物凋落物分解微生物群落的影响,在天津滨海湿地采集原状土壤和芦苇叶片凋落物,通过模拟增温和增氮实验,分析不同温度和氮输入水平条件下芦苇凋落物可培养细菌和真菌数量、群落组成和多样性的差异,并分析细菌和真菌群落组成与土壤理化因子间的相关关系.结果表明:增温处理能够使细菌数量下降,对真菌数量无显著影响.氮输入水平增加可使细菌数量下降,使真菌数量呈先上升再下降的趋势.常温处理中,细菌群落多样性随氮输入水平增加而上升,增温处理中,细菌群落多样性随氮输入水平增加而下降;增温和增氮处理均可降低真菌群落的多样性.冗余分析显示,对细菌群落组成起主导作用的土壤因子为土壤总磷含量(解释度16.40%)、亚硝态氮含量(解释度14.10%)和铵态氮含量(解释度12.70%);对真菌群落组成起主导作用的土壤因子为土壤亚硝态氮含量(解释度16.70%)和pH值(解释度12.40%).

To explore the effects of warming and nitrogen input increase on composition and diversity of decomposing microbial communities of plant litter in coastal wetland,the undisturbed soil and leaf litter of Phragmites australis were collected in Tianjin coastal wetland.The number,community composition and diversity of culturable bacteria and fungi in P.australis litter under different temperature and nitrogen input levels were analyzed by simulated warming and nitrogen enrichment experiments.And the relationship between community composition of bacteria and fungi and soil physical and chemical factors was analyzed.The results showed that warming decreased the quantity of culturable bacteria,but had no significant effects on the quantity of culturable fungi.With the increase of nitrogen input level,the quantity of culturable bacteria decreased,while the quantity of culturable fungi increased at first and then decreased.With the increase of nitrogen input level,diversity of culturable bacteria community increased in the ambient temperature treatment,but decreased in the warming treatment.Warming and nitrogen input increase both decreased the diversity of culturable fungi community.Redundancy analysis showed that the main soil factors influencing composition of culturable bacteria community included soil total phosphorus content(explanation percentage 16.40%),nitrite nitrogen content(explanation percentage 14.10%)and ammonium nitrogen content(explanation percentage 12.70%),and the main soil factors influencing composition of culturable fungi community included soil nitrite nitrogen content(explanation percentage 16.70%)and pH(explanation percentage 12.40%).