猫儿山不同海拔植被带土壤微生物群落功能多样性

为研究中亚热带森林土壤微生物群落功能多样性特征及其随海拔梯度的变化,应用Biolog微平板技术,对猫儿山不同海拔植被带(常绿阔叶林(EBF)、落叶阔叶混交林(DBF)、针阔混交林(CBF))土壤微生物群落功能多样性差异进行了比较。结果表明,不同海拔植被带土壤微生物群落功能多样性差异显著。土壤平均颜色变化率(AWCD)随培养时间延长而逐渐增加,随着海拔升高,土壤AWCD值逐渐降低,大小顺序为EBFDBFCBF。土壤微生物群落Shannon指数和丰富度指数的总体趋势为EBF最高,DBF次之,CBF最低。不同海拔植被带土壤微生物群落均匀度指数之间差异不显著。不同海拔植被带土壤微生物对不同碳源的利用能力存在差异,其中EBF利用率最高,CBF利用率最低,氨基酸类、胺类和酯类碳源为各海拔植被带土壤微生物利用的主要碳源。主成分分析结果表明,主成分1和主成分2分别能解释变量方差的40.42%和15.97%,在主成分分离中起主要贡献作用的是酯类、胺类和氨基酸类碳源。土壤理化性质与土壤微生物群落功能多样性之间的相关性分析结果表明,微生物群落多样性的Shannon指数与全钾(TK)呈极显著正相关(P0.01),与含水量呈极显著负相关(P0.01),与总有机碳(TOC)、全氮(TN)、速效氮(AN)、有效P(AP)之间的相关性显著(P0.05)或极显著(P0.01),且为负相关。土壤TK含量和含水量可能是造成不同海拔土壤微生物群落功能多样性差异的主要原因。

Variation of soil microbial community diversity along an elevational gradient in the Mao'er Mountain forest

In order to study the characteristics of soil microbial functional diversity in mid-subtropical forest and their changes along an altitudinal gradient, Biolog microplate analysis was used to investigate into the functional diversity of microbial communities under three vegetation zones in the National Natural Reserve of Maoer Mountain. The vegetation zones were evergreen broad-leaved forest (EBF), deciduous broad-leaved forest (DBF) and coniferous and broad-leaved forest (CBF). The results showed that the functional diversities of soil microbial communities were significantly different in different altitudes. The average well color development (AWCD) of soil microbial community which reflects the utilization of sole carbon source is taken as an important indicator of soil microbial activity and functional diversity. The AWCDs in different vegetation belts increased with culturing time and decreased gradually with the altitude in an order of EBF > DBF > CBF. Soil physical-chemical properties in different vegetation belts along an elevation gradient were significantly different. Soil pH and total K were monotonic decreasing while soil water content was monotonic increasing. Shannon diversity and richness indexes of microbial communities in EBF were the highest, followed by DBF and CBF. No significant differences in evenness index of microbial communities were found in different altitudes. Carbon source utilization was significantly different in different altitudes, where EBF and CBF were the highest and lowest, respectively. Amino acids, amines, and esters were the main carbon sources. Two factors of carbon sources were identified using the principal component analysis, explaining 40.42% and 15.97% of the total variances, respectively. The two factors were separated mainly due to carbon sources of esters, amines, and amino acids. Correlation analysis was used to evaluate the correlation of soil physical-chemical properties and microbial community functional diversity. The results showed that the Shannon diversity indexes of the three vegetation zones were positively correlated with TK at the most statistically significant level of 0.01, negatively correlated with soil water content at the most statistically significant level of 0.01, and negatively correlated with TOC, TN, AN, and AP at significant levels of 0.01 or 0.05. The correlation between soil physical-chemical properties and microbial community functional Shannon index was significant. We conclude that soil physical-chemical properties and microbial community functional diversity along an altitudinal gradient showed some regularity. Different TK and water contents in soil could be the main reasons for the variation of microbial community diversity in the soils under the vegetation zones.