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氮沉降虽可提升林地生产力却会给环境造成压力,而土壤微生物对环境变化敏感.通过野外模拟试验,探讨不同氮沉降量对马尾松土壤微生物群落的影响,探索该区域马尾松土壤微生物群落与土壤温湿度、氮沉降浓度的关系,为深入研究氮沉降对马尾松林土壤生态系统的影响提供参考.2014年5月~2015年6月在缙云山马尾松林设置3个氮添加水平和一个无氮添加的对照处理:低氮[N20,20 g·(m~2·a)~(-1)]、中氮[N40,40 g·(m~2·a)~(-1)]、高氮[N60,60 g·(m~2·a)~(-1)]和对照[N0,0g·(m~2·a)~(-1)],采用磷脂脂肪酸(PLFA)标记法和ACE(automated soil CO_2 exchange station,UK)自动土壤呼吸监测系统分别对土壤微生物群落结构、土壤温度和土壤湿度进行分析测定.结果表明:1季节变化对土壤细菌、真菌、放线菌及总PLFA量有显著影响(P<0.05),各类型均在春季最高,冬季最低.在不同季节,土壤微生物量对氮沉降的响应趋势不同,总体而言,春季和秋季氮沉降抑制了土壤微生物量,夏季和冬季氮沉降促进了土壤微生物量.2氮沉降对土壤微生物群落结构有显著影响(P<0.05),在春季和夏季,低、中氮沉降使土壤微生物丰富度指数和多样性降低,使均匀度指数升高;在秋季和冬季,低氮和中氮则使丰富度指数、多样性指数及均匀度指数升高.高氮沉降使4个季节土壤微生物丰富度指数、多样性指数和均匀度指数降低.3相关性分析表明,氮沉降浓度与细菌呈极显著负相关(P<0.01),与总PLFA呈显著负相关(P<0.05);土壤温度与放线菌呈极显著负相关;土壤湿度与细菌和总PLFA呈极显著正相关.综上所述,缙云山马尾松林土壤微生物群落结构主要受土壤湿度和氮沉降的影响,受土壤温度影响较小.
Nitrogen deposition can increase the productivity of woodland, but it will cause environmental pressure, and soil microorganisms are sensitive to environmental changes.Through the field simulation test to explore the impact of different nitrogen deposition on soil microbial community of Pinus massoniana, to explore the masson community of Pinus massoniana and Soil temperature and humidity, nitrogen deposition concentration, to provide a reference for further study on the impact of nitrogen deposition on soil ecosystem of Pinus massoniana forest.Monon-pine massif in Jinyun Mountain from May 2014 to June 2015 was set up with three nitrogen addition levels and one nitrogen-free addition (N20, 20 g · (m -2 · a -1)], N [N40,40 g · (m -2 · a -1)], high nitrogen [N60, 60 g · (m -2 · a -1)] and control [N 0,0 · g · (m -2 · a -1)] were assayed by phospholipid fatty acid (PLFA) The soil microbial community structure, soil temperature and soil moisture were analyzed by automatic soil respiration monitoring system (automated soil CO_2 exchange station, UK). The results showed that the seasonal variation of soil microbial community, fungi, actinomycetes and total PLFA (P <0.05), with the highest in spring and the lowest in winter in each type.The response of soil microbial biomass to nitrogen deposition in different seasons In general, nitrogen deposition in spring and autumn inhibited soil microbial biomass, and nitrogen deposition in summer and winter promoted soil microbial biomass.2 Nitrogen deposition had a significant effect on soil microbial community structure (P <0.05), and in spring and summer Under low and medium nitrogen deposition, the soil microbial abundance index and diversity decreased, and the evenness index increased. In autumn and winter, low nitrogen and medium nitrogen increased the richness index, diversity index and evenness index. High nitrogen deposition decreased soil microbial abundance index, diversity index and evenness index in four seasons.3 Correlation analysis showed that nitrogen deposition concentration was significantly and negatively correlated with bacteria (P <0.01), and negatively correlated with total PLFA (P <0.05). Soil temperature had a significantly negative correlation with actinomycetes, and soil moisture had a significant positive correlation with bacteria and total PLFA.In summary, the soil microbial community structure in Pinus massoniana forest in Jinyun Mountain was mainly affected by soil moisture and nitrogen The effect of subsidence is less affected by soil temperature.