吉林蛟河针阔混交林群落β多样性的影响因素

Factors influencingβdiversity of coniferous and broad-leaved mixed forest in Jiaohe,Jilin Province,China

量化局部因素对区域群落间物种组成差异的相对作用,对于理解吉林蛟河针阔混交林群落β多样性的响应机制具有重要意义.将区域群落尺度定义成由3个、5个或9个样方构成的3个梯度,并把全部木本植物划分为3个垂直层,计算不同林层下各区域群落的β多样性.采用回归模型和方差分解法分析地形和生物变量对不同区域群落β多样性的影响及相对贡献.结果表明:不同林层β多样性随着区域群落尺度的增大呈显著增大趋势(P<0.05),其中林下层变化范围为0.359-0.373,亚林层范围为0.502-0.514,林冠层范围为0.448-0.473;生物变量表征的林分结构属性对区域群落β多样性的影响最大,其解释比例总体上随区域群落尺度的增大而增大(林下层:0.27→0.40→0.33;亚林层:0.20→0.29→0.37;林冠层:0.16→0.21→0.27);不同林层中影响β多样性的生物因子种类不同,林下层和林冠层的决定性因素为物种丰富度,而亚林层的决定性因素为胸径变异系数;而地形因子对区域群落β多样性的解释量较低,其中海拔对林下层和林冠层具有显著的正向影响,坡度对亚林层具有显著的负向影响.本研究证实了区域群落尺度和林分结构特征对β多样性格局的形成具有重要作用,为今后全面揭示温带森林群落的多样性维持机制提供新视角.(图4表2参37)

Quantifying the relative effects of local factors on species composition differences among regional communities is important for understanding the response mechanism ofβ-diversity in the coniferous and broadleaved mixed forest in Jiaohe,Jilin Province,China.In this study,the regional community-scale was defined as three gradients,consisting of three,five,or nine plots.All woody plants were divided into three vertical strata,and theβ-diversity of each regional community under different forest strata was calculated.A regression model and variation partitioning analysis were used to analyze the effects and relative contributions of topographic and biotic variables on theβ-diversity of different regional communities.Theβdiversity of different forest layers increased significantly with increasing scale(P<0.05).The variation range from understory to canopy was 0.359-0.373,0.502-0.514,0.448-0.473,respectively.Theβ-diversity of the regional community was most affected by the stand structural features represented by biotic variables.The proportion of their interpretation generally increased with increasing scale(understory:0.27→0.40→0.33;substory:0.20→0.29→0.37;canopy:0.16→0.21→0.27).Different biotic factors affectedβdiversity in the different forest layers.In the understory and canopy,species richness was the decisive factor,whereas VarDBH was the decisive factor in the substory.However,the relative importance of the topographic factors was negligible.Elevation had a significant positive effect on the understory and canopy,whereas slope had a significant negative effect on the substory.This study confirms the importance of regional community scale and community features onβ-diversity patterns and provides a new perspective to fully reveal the mechanisms of biodiversity maintenance in temperate forest communities.