嘉陵江流域不同土地利用类型土壤微生物功能多样性特征

基于2013—2015年对嘉陵江流域中游(四川段)不同土地利用类型(混交林、草甸、针叶林、阔叶林、灌丛和裸地)土壤生境的调查分析数据,利用Biolog微平板法和磷脂脂肪酸甲酯法(FAMEs)系统研究了土壤微生物多样性群落特征。不同土地利用类型土壤养分和有效养分基本表现为混交林阔叶林针叶林灌丛草甸裸地。不同土地利用类型土壤微生物群落代谢平均颜色变化率(AWCD)随培养时间延长而逐渐增加,土壤微生物群落代谢活性依次是混交林阔叶林针叶林灌丛草甸裸地。土壤微生物对不同种类碳源的利用强度存在较大差异,碳水化合物和羧酸类碳源是不同土地利用类型土壤微生物的主要碳源,其次为氨基酸类、酚酸类和聚合物类,胺类碳源的利用率最小。土壤微生物群落的物种丰富度指数(H)、均匀度指数(E)、优势度指数(Ds)和碳源利用丰富度指数(S)总体趋势为混交林最高,针叶林和阔叶林次之,裸地最低,优势度指数在不同土地利用类型差异并不显著(p0.05)。主成分分析结果表明,从31个因素中提取的与碳源利用相关的主成分1,主成分2分别能解释变量方差的65.154%和81.047%,在主成分分离中起主要贡献作用的是胺类和氨基酸类碳源;土壤微生物多样性指数与土壤养分之间呈正相关,与pH值呈负相关,而土壤全碳和全氮含量对土壤微生物多样性贡献较大,这是造成土壤微生物群落功能多样性差异的主要原因。H,E和S与土壤养分各指标的相关系数绝对值均高于Ds,说明了土壤养分对土壤微生物群落优势度指数的影响作用较小。

Variation of Soil Nutrients and Microbial Community Diversity of Different Land Use Types in the Jialing River,Sichuan Province

We present a comprehensive analysis of soil nutrients and soil microbial community diversity of different land use types in Jialing River from 2013 to 2015,based on the soil habitat,the structure and function of soil microbial community were studied by using Biolog plate and phospholipid fatty acid methyl ester (FAMEs),respectively.The results are as follows.The soil nutrients of different land use types decrease in the order:mingled forest＞broad-leaved forest＞coniferous forest＞shrub＞meadow＞bare land.There were significant differences in functional diversity of microbial communities of different land use types.The average well color development (AWCD),which directly reflects microbial activity and functional diversity,increased and then decreased with the order:mingled forest＞broad-leaved forest＞coniferous forest＞shrub ＞meadow＞bare land.The carbon sources mostly used by soil microbes were carbohydrates and carboxylic acids,followed by amino acids,phenolic acids and polymers,the lowest was amines.The Simpson index,Shannon-Wiener index,richness index and McIntosh index of different land use types showed the sequence:mingled forest＞ broad-leaved forest＞ coniferous forest＞ shrub＞ meadow＞ bare land.Principal component analysis identified two factors in relation to carbon sources,they explained 65.154％ and 81.047％ of the variation,respectively.The carbon sources used by soil microbial communities were different among different land use types.Amino acids and amides were the two main carbon sources separating the two principal component factors.Correlation analysis showed that soil microbial diversity index was significantly or very significantly positively correlated with soil nutrients,and was negatively correlated with pH value,the soil nutrients had the more positive contribution to soil microbial diversity and soil pH value had the negative contribution,which were the reason for variation of soil microbial community diversity of different land use types in Jialing River.