温带针阔混交林生物量稳定性影响机制

Impact and mechanism of maintaining biomass stability in a temperate coniferous and broadleaved mixed forest

森林生态系统通过响应环境波动和干扰而产生时间变化,对其稳定性机制的研究有利于生态系统服务。温带针阔混交林是全球森林生态系统的重要组成部分,该研究致力于探索超产效应、林分结构、物种异步性及优势物种稳定性对温带天然针阔混交林群落稳定性的影响,以明确主要影响机制。该研究分别设定物种丰富度、胸径变异系数、物种异步性和优势物种稳定性为解释变量,群落生物量稳定性、生物量平均值和生物量标准差为响应变量,构建3个结构方程模型,比较各变量间直接与间接效应的相对大小。主要结果为:(1)结构方程模型提供了良好的拟合效果,并占群落生物量稳定性变化的40.6%;(2)物种丰富度与生物量平均值、生物量标准差均呈显著负相关关系,路径系数分别为–0.103和–0.061;(3)胸径变异系数与群落生物量稳定性及生物量平均值均呈显著负相关关系,路径系数分别为–0.123和–0.097;(4)物种异步性与群落生物量稳定性、生物量平均值、生物量标准差均呈显著正相关关系,路径系数分别为0.055、0.085和0.055;(5)优势物种稳定性与群落生物量稳定性和生物量平均值呈显著正相关关系,路径系数分别为0.623和0.085,与生物量标准差间显著负相关,路径系数为–0.608。研究结果表明尽管林分结构和物种异步性对温带针阔混交林群落生物量稳定性均有显著影响,但优势物种稳定性是最主要的直接影响因素。

Aims Forest ecosystem changes with time in response to environmental fluctuations and disturbances,and the research on its stability and influence mechanism is conducive to maintaining ecosystem services.The temperate coniferous and broadleaved mixed forest is an important component of the global forest ecosystem.Therefore,we aimed to investigate the influence of overyielding,stand structure,species asynchrony and dominant species stability on the community stability of a temperate natural coniferous and broadleaved mixed forest and to clarify its main influence mechanism.Methods In this study,species richness,coefficient of variation of diameter at breast height(DBH),species asynchrony,and dominant species stability were used as independent variables,and community biomass stability,mean biomass and standard deviation of biomass were set as dependent variables,respectively.In this case,three structural equation models were constructed to quantify the relative size of the direct and indirect effects among all variables.Important findings(1)The structural equation model provides a good fit for the data and accounts for 40.6%of the community biomass stability changes.(2)Species richness was significantly negatively correlated with mean biomass and standard deviation of biomass,with the path coefficients–0.103 and–0.061,respectively.(3)The coefficient of variation of DBH was significantly negatively correlated with the community biomass stability and mean biomass,and the path coefficients were–0.123 and–0.097,respectively.(4)Species asynchrony was significantly positively correlated with the community biomass stability,mean biomass and standard deviation of biomass,and the path coefficients were 0.055,0.085 and 0.055,respectively.(5)Dominant species stability was significantly positively correlated with the community biomass stability and mean biomass,with the path coefficients 0.623 and 0.085,respectively.And it has a significant negative correlation with the standard deviation of biomass,with the path coefficient–0.68.The results showed that although species asynchrony and stand structure both have significant effects on the community’s biomass stability in the temperate coniferous and broadleaved mixed forest,but the dominant species stability is the main factor that directly affects the community biomass stability.