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【目的】探究氮沉降对杨树人工林土壤微生物群落特征的影响。【方法】以江苏省东台地区沿海杨树人工林为对象,采用Biolog ECO微平板技术,设置4种氮添加水平:N0(0 kg/(hm~2·a))、N1(50 kg/(hm~2·a))、N2(100 kg/(hm~2·a))、N3(150 kg/(hm~2·a))模拟不同浓度氮沉降,经过2 a生长季(5—10月)处理,测定杨树林土壤微生物群落碳源利用变化情况。【结果】N2处理可以增强杨树人工林土壤微生物对碳源的代谢能力,氮添加浓度过高则会产生抑制作用;土壤中微生物对胺类和酚类利用程度表现出较大差异,其中,酚类在高浓度氮处理(N3)时利用程度最高,胺类在低浓度氮(N1)条件下利用程度最高;硝态氮和平均颜色变化率(AWCD)、Shannon多样性均具有显著正相关性(P<0.05),微生物代谢水平及其结构变化受到硝态氮影响较大。主成分分析表明,PC1和PC2可以表示施氮对微生物群落代谢多样性产生的差异,其中,PC1的方差贡献率最大,碳水化合物、酚类呈负相关(碳源相关系数分别为-0.869、-0.780),氨基酸、羧酸呈正相关(碳源相关系数分别为0.702、0.821),是起主要分异作用的碳源;PC2涵盖了聚合物和胺类两种碳源大类,其中聚合物呈负相关(相关系数为-0.688),胺类呈正相关(相关系数为0.802)。【结论】氮添加会导致杨树人工林土壤微生物群落对碳源利用类型改变,土壤中硝态氮含量与微生物生长代谢及功能多样性呈显著正相关;六大类碳源中碳水化合物、羧酸是影响土壤微生物群落功能多样性的主要碳源。
【Objective】 The objective of this study was to investigate the effect of nitrogen deposition on the characteristics of soil microbial community in poplar plantations. 【Method】 With the Biolog ECO microplate technique, four nitrogen levels were added to the coastal poplar plantations in Dongtai, Jiangsu Province: N0 (0 kg / (hm ~ 2 · a)), N1 (50 kg / ( N 2 (100 kg / (hm ~ 2 · a)) and N 3 (150 kg / (hm 2 · a)) simulated the deposition of nitrogen at different concentrations. After 2 years of growing season Month) to determine the changes of carbon source utilization in the soil microbial communities. 【Result】 The results showed that N2 treatment could enhance the metabolism of soil microbial resources to carbon sources in poplar plantations, and inhibited the growth of nitrogen sources when the concentration of nitrogen was too high. The utilization rate of amines and phenols by soil microorganisms showed great differences. Among them, Phenols had the highest degree of utilization in the treatment of high concentration of nitrogen (N3), and the highest degree of utilization of amines in the low concentration of nitrogen (N1). There was a significant positive correlation between nitrate and average color change rate (AWCD) and Shannon’s diversity (P <0.05). The level of microbial metabolism and its structural changes were greatly influenced by nitrate nitrogen. Principal component analysis showed that PC1 and PC2 could be used to indicate the differences in microbial metabolic diversity. Among them, PC1 had the largest variance contribution and the carbohydrates and phenols were negatively correlated (the correlation coefficients of carbon sources were -0.869 and - 0.780), amino acids and carboxylic acids (carbon source correlation coefficients were 0.702,0.821, respectively), which was the carbon source that played a major role in differentiation. PC2 covered two major carbon and polymer categories: polymers and amines Negative correlation (correlation coefficient -0.688), amines showed a positive correlation (correlation coefficient 0.802). 【Conclusion】 Nitrogen addition can lead to changes in the types of carbon sources in soil microbial communities in poplar plantations, and significant positive correlations between nitrate nitrogen content in soil and microbial growth, metabolism and functional diversity. Carbohydrate, carboxy Acids are the major carbon sources that affect the functional diversity of soil microbial communities.