北京海坨山典型林分土壤固氮菌群落特征研究

Characteristics of Soil Nitrogen-Fixing Bacteria Community of Typical Forest Stands at Haituo Mountain,Beijing

[目的]探讨北京海坨山不同林分类型下土壤固氮菌多样性和群落结构及其与土壤性质的相关关系,为暖温带森林土壤氮循环及森林植被恢复提供理论依据。[方法]选择4种典型林分类型(油松林(Pinus tabuliformis Carriere)、针阔混交林(Pine-poplar mixed)、蒙古栎林(Quercus mongolica Fisch)、核桃楸林(Juglans mandshurica Maxim))分别设置3块(20 m×20 m)标准样地,采集0~20 cm土层土样,分析相关土壤性质,采用高通量测序分析土壤固氮菌多样性和群落结构特征,并探究不同土壤特性对土壤固氮微生物群落特征的影响。[结果]4种林型下共测定出4门6纲13目16科29属。多样性分析显示,4种林型下土壤固氮菌α多样性存在显著差异,具体表现为油松林>针阔混交林>核桃楸林>蒙古栎林。β多样性分析显示,4种林型土壤固氮菌群落组间差异大于组内差异。在已鉴定的土壤固氮菌中,各林型以变形菌门为主,核心菌属为慢生根瘤菌属、广泛固氮氢自养单胞菌属和斯克尔曼氏菌属。RDA分析显示,土壤特性能解释固氮菌群落变异的65.48%,其中土壤有机质和全氮含量显著影响4种林型下土壤固氮菌群落组成。[结论]北京海坨山地区土壤固氮菌资源丰富,不同林型下土壤特性、固氮菌多样性和群落结构差异明显,其中土壤有机质和全氮含量是显著影响土壤固氮菌群落组成的主要因子。

[Objective]To provide theoretical evidence relating to forest soil nitrogen circulation and forest vegetation restoration in warm temperate forests,the diversity,composition of soil nitrogen-fixing bacteria community and their relations with soil properties were studied in four different forest types in Songshan National Nature Reserve of Beijing.[Method]Four typical forest stands(Pinus tabuliformis Carriere(Pt),Pine-poplar mixed(Mix),Quercus mongolica Fisch(Qm)and Juglans mandshurica Maxim(Jm))were selected with three replicate plots(20 m×20 m).Soil samples of 0~20 cm soil layer were collected from each plot to analyze soil properties.In this study,real-time quantitative PCR and High-throughput sequencing were used to study the diversity and composition of soil nitrogen-fixing bacteria.Pearson’s correlation analysis and redundancy analysis(RDA)were used to examine the soil properties factors driving the community structure and diversity of the soil nitrogen-fixing bacteria.[Result]A total of 4 phyla,6 classes,13 orders,16 families and 29 genera were detected from the soil samples.There were significant differences in theαdiversity of soil nitrogen-fixing bacteria in the four forest types with Pt>Mix>Jm>Qm.β-diversity analysis showed that the inter-group differences of soil nitrogen-fixing bacteria communities of the four forest types were greater than the intra-group differences..Proteobacteria was the dominant phylum.Bradyhizobium,Azohydromonas and Skermanella were the dominant genera in all soil samples.Redundancy analysis(RDA)showed that soil properties could explain 65.48%of the variation of soil nitrogen-fixing bacteria community.Soil organic matter and total nitrogen were the main factors affecting the structure and diversity of the soil nitrogen-fixing bacteria community.[Conclusion]There are abundant soil nitrogen-fixing bacteria resources in Haituo Mountain.There are significant differences in soil properties,soil nitrogen-fixing bacteria diversity and community structure under different forest stands.Soil organic matter and total nitrogen are the main soil properties factors that significantly affect the soil nitrogen-fixing bacteria in Haituo Mountains.