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Effects of simulated nitrogen deposition on soil microbial community structure in different seasons of Citrus Forest in Mt.Jinyun, Chongqing

2020-05-02 15:55:27 柑橘树

泥土微生物积极主动参与生态系统的物质循环和转化.人类主题活动导致全球氮沉降量激增,引起泥土微生物群落结构和功用的变更,进而造成生态系统失衡.2014年6月-2015年5月在缙云山柑橘林建立郊外模拟氮沉降试验样地,原位设置4个施肥程度:对比(N0,0 g·m-2·a-1)(以N计,下同)、低氮(N20,20 g·m-2·a-1),中氮(N40,40 g·m-2·a-1)和高氮(N60,60 g·m‘·a-1).施氮处理2d后,采用磷脂脂肪酸(PLFA)标识法和ACE(Automated Soil CO2 Exchange Station,UK)自动泥土呼吸监测系统对泥土微生物群落结构、泥土温湿度发起测定.研究阐明:①不同样时节泥土微生物对氮沉降的响应不一,春天氮沉降抑制泥土微生物量,夏、秋、冬季N40处理提高了泥土微生物量,N20、N60表现为抑制泥土微生物量;氮沉降对泥土温度有显著影响,但对泥土湿度影响不明显(p<0.05).②泥土微生物丰厚度指数和Shannon-Wiener多样性指数在中氮沉降条件下达最大;Pielou匀称度指数则表现不同致,春天和夏季在中氮浓度下最大,秋季在高氮处理下最大,冬季则在低氮处理下最大.③泥土温度与放线菌呈显著负相关(p<0.01);泥土湿度与细菌和总PLFA呈显著正相关(p<0.01),与放线菌呈显著正相关(p<0.05).综合剖析阐明,泥土微生物受泥土温度和含水量的共同影响,氮沉降减少了泥土微生物含量,此研究结果支持了氮沉降抑制泥土微生物的认识.

<span>Abstract: 

Soil microorganisms are of great significance to element circulation and transformation in ecosystems.The great increase in nitrogen deposition caused by human activities could change the structure and function of soil microbes,and then disturb the balance of ecosystem.An on-site experiment was conducted in citrus forest of Mt.Jinyun from June 2014 to May 2015.Nitrogen treatments were designed at four levels:control (No,0 g· m-2· a-1),low nitrogen (N20,20 g·m-2· a-1),moderate nitrogen (N40,40 g· m-L a-1) and high nitrogen (N60,60 g· m-2· a-1).The influences of fertilization on the structure of soil microbial community and soil temperature and moisture were investigated by using phosphorus lipid fatty acids (PLFAs) and automated soil CO2 exchange station,respectively.The results showed that the response of soil microorganisms to nitrogen deposition varied with seasons greatly.Generally,nitrogen deposition decreased soil microbial population from all treatments in spring and from the treatment of N20 and N60 in summer,autumn and winter,but increased the soil microbial biomass from N4o treatment in summer,autumn and winter.Moderate nitrogen treatment significantly increased microbial richness and diversity,while the responses of the Pielou evenness index to nitrogen deposition changed with seasons.The maximum values of the Pielou evenness index were observed in autumn under high nitrogen treatment and in winter under low nitrogen treatment,but in spring and summer under medium nitrogen concentration.There was a significantly negative correlation between soil temperature and actinomycetes.Soil moisture was positively correlated with bacteria,total PLFA and actinomycetes.Therefore,it is concluded that soil microbes were affected by soil temperature and moisture content,but nitrogen deposition could reduce soil microbial biomass.Thus,our experimental results clearly confirmed the insight that nitrogen deposition restrained soil microorganisms.

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