武夷山黄山松林土壤细菌群落特征沿海拔梯度的分布模式

Distribution pattern of soil bacterial community characteristics in a Pinus taiwanensis forest along an elevational gradient of Wuyi Mountains

土壤细菌是微生物群落的重要组成部分。目前,关于土壤细菌沿海拔梯度分布的研究主要集中在不同植被类型和生态系统差异较大的海拔梯度上,而在不同海拔相同植被类型下土壤细菌群落多样性、结构和功能的分布规律仍有待探究;另外,土壤细菌群落结构和功能之间如何联系尚不清楚。本研究以亚热带武夷山不同海拔(1200、1400、1600、1800和2000 m)黄山松林为对象,通过16S rDNA高通量测序技术和PICRUSt功能预测分析,探究土壤细菌群落特征(多样性、结构和功能)沿海拔梯度的分布格局及其驱动因素。结果表明:(1)0~10和10~20 cm土壤细菌群落多样性沿海拔梯度呈非线性分布,其群落结构在较高海拔(1800、2000 m)与较低海拔(1200、1400、1600 m)之间存在显著差异;(2)功能预测分析共得到6类一级生物代谢通路,包括46个二级代谢通路功能,表现出功能上的丰富性,且丰度较高的预测功能基因在海拔梯度上均具有显著差异,其中碳水化合物代谢,能量代谢,辅因子与维生素代谢,转化和折叠、分类与降解等的相对丰度随海拔升高呈增加的趋势;而氨基酸代谢、生物降解与代谢、膜转运、信号传导、细胞运动、细胞生长与死亡、药物抗性和环境适应等则相反;(3)不同海拔土壤细菌二级代谢通路预测基因相对丰度的变化与变形菌门、放线菌门和绿弯菌门相对丰度的变化存在显著相关性,土壤细菌预测功能基因组成的差异随细菌群落结构而变化,反映出细菌群落结构与功能可能具有密切的联系;(4)土壤温度和pH是影响0~10 cm土壤细菌群落结构和预测功能基因的关键因素,而在10~20 cm土壤中,其关键的影响因素为pH和可溶性有机碳。本研究揭示了武夷山黄山松林土壤细菌群落特征沿海拔梯度的分布模式及其驱动因素,为进一步认识土壤细菌群落对环境变化的响应以及亚热带山地森林土壤生态系统功能的变化提供依据。

Soil bacteria are an important part of the microbial community.Previous studies on soil bacteria along elevational gradients have mainly focused on different vegetation types and ecosystems with great differences.However,the distribution of soil bacterial community diversity,structure,and function of the same vegetation type along an elevational gradient remains to be explored,and the relationship between soil bacterial community structure and function is unclear.In this study,we used 16 S rDNA sequencing technology and PICRUSt predicted functions to probe the characteristics of soil bacterial community diversity,structure,and function and influencing factors in a Pinus taiwanensis forest along an elevational gradient in the subtropical Wuyi Mountains.The results showed that:(1) Soil bacterial community diversity at 0-10 and 10-20 cm depth showed a nonlinear change along the elevational gradient.The community structure was significantly different between higher elevations(1800,2000 m) and lower elevations(1200,1400,1600 m).(2) Predicted functions analysis showed six classes of level Ⅰ metabolic pathways,including 46 level Ⅱ metabolic pathways(showing rich functions),and predicted functional genes with high abundance exhibited significant differences along the elevational gradient.The relative abundances of carbohydrate metabolism,energy metabolism,metabolism of cofactors and vitamins,translation,folding,sorting,and degradation demonstrated an increasing trend with elevation.However,amino acid metabolism,xenobiotics biodegradation and metabolism,membrane transport,signal transduction,cell motility,cell growth and death,antimicrobial drug resistance,and environmental adaptation showed a decreasing trend.(3) There was a significant correlation between the relative abundance of genes involved in the level Ⅱ metabolic pathway of bacteria and relative abundance of Proteobacteria,Actinobacteria and Chloroflexi at different elevations.The differences of the predicted functional gene composition varied with bacterial community structure,which indicates that structure and function of bacterial community may be closely related.(4) Soil temperature and pH were the key factors affecting bacterial community structure and predicting functional genes in 0-10 cm layer,while pH and dissolved organic carbon were the key influencing factors in 10-20 cm layer.This study reveals the characteristics and driving factors behind the diversity,structure,and predicted functions of soil bacterial communities in a P.taiwanensis forest along an elevational gradient of Wuyi Mountains.Our findings provide a theoretical basis for further understanding the responses of soil bacterial communities to environmental changes,and the change of soil function in subtropical mountain forest ecosystems.