车八岭山地常绿阔叶林冰灾后土壤微生物群落功能多样性

研究了我国南方冰灾后常绿阔叶林林冠开度及土壤养分的空间异质性对土壤微生物功能多样性的影响.在受冰灾影响的粤北车八岭山地常绿阔叶林2 hm2固定样地中按照冠层受损程度选取16个20 m×20 m的样方,用半球面影像技术获取林冠开度,并取0～20 cm的表层土壤混合样品分析土壤的理化性质,同时应用Biolog技术分析微生物功能多样性.按林冠开度梯度对各样方土壤微生物群落利用单一碳源的分析发现,林冠开度大的样方土壤微生物的活性、丰富度、多样性和均匀度都较低,反之则较高.聚类分析的结果与林冠开度的梯度有高度的一致性.主成分分析表明各样方土壤微生物功能多样性具有显著差异(第一轴p<0.005;第二轴p<0.001),其结果与聚类结果基本吻合.冗余分析揭示了土壤全磷、全钾、全氮、速效氮、有机碳、容重、总孔隙度和林冠开度的综合作用对土壤微生物功能多样性有显著影响(p<0.005),其中林冠开度与土壤微生物群落功能多样性的关系最密切.土壤微生物功能多样性受土壤养分的影响,具体表现为:与土壤有机碳呈明显的正相关;与全氮正相关;与速效氮、全磷负相关.研究说明冰灾所造成林冠开度和土壤养分的空间异质性会影响到土壤微生物功能多样性,而土壤微生物功能多样性可用于对生境恢复的指示和评价.

Soil microbial functional diversity in a montane evergreen broadleaved forest of Chebaling Following the Huge Ice Storm in South China

Effect of spatial heterogeneity in canopy openness and soil nutrients on soil microbial functional diversity was investigated following a huge ice storm in south China. Sixteen plots, each 400 m~2, were selected for this study according to the damage degrees of the canopy within a 2 hm~2 permanent plot, which had been set up within the storm-hit montane evergreen broadleaved forest in Chebaling National Nature Reserve. Canopy openness was estimated with hemispherical photography, and a composite sample of surface soil (0-20 cm) was collected from each plot for the analyses of soil properties as well as microbial functional diversity using Biolog. In accordance with canopy openness groups, the activity, richness, diversity and evenness of soil microbial communities decreased with the canopy openness. Cluster analysis confirmed that the plot clusters had high consistency with the canopy openness groups, while Principal Component Analysis indicated that soil microbial functional diversity was significantly different among plots (Axis 1 and Axis 2: p<0.005). Redundancy analysis demonstrated that the combining effect of soil total phosphorus,total potassium,total nitrogen,available nitrogen,soil organic carbon,soil bulk density,total porosity and canopy openness had significant influence (p<0.005) on the utilization of sole carbon source by soil microbial community, with canopy openness as the major factor. Soil microbial functional diversity was positively correlated with soil organic carbon and total nitrogen and negatively with available nitrogen and total phosphorus. These findings suggested that changes in canopy structure and soil nutrients following the ice storm might affect soil microbial functional diversity, thus these functional traits of microbial communities can be used as indicators to monitor and evaluate habitat restoration.