喀斯特常绿落叶阔叶混交林植被的空间异质性

Spatial Heterogeneity of Vegetation in Karst Mixed Forest of Evergreen and Deciduous Broadleaf

基于广西环江木论国家级自然保护区喀斯特典型峰丛洼地常绿落叶阔叶混交林2 hm2动态监测样地,选择4个多样性和5个群落结构属性变量,运用地统计学和分形几何学理论方法,分析植被的空间异质性、分形特征和分布格局,以探讨其维持机制。结果表明:(1)样地树木种类和除平均高度外的4个结构属性变量均值适中,变异系数较高(48.37%～71.01%),植物多样性丰富且稳定性强,Shannon指数、Simpson指数和均匀度指数变异系数仅在5.49%～22.64%之间。(2)除均匀度的Moran’s I系数接近0且无规律外,其他8个属性变量均有不同程度的空间自相关性,分别用球状、指数和高斯模型拟合的决定系数(R2)高达0.900～0.982,C/(C0+C)值和分维数D值分别在0.582～0.827和1.738～1.871之间,具有中等以上的空间依赖性。(3)密度、平均冠幅和高度的自相关范围和变程小于其他指标,其分布和形成过程决定了整个森林植被的空间格局。(4)森林植被的Kriging等值线图充分表征了人为干扰、地形、土壤质量的综合差异。(5)自相关、半方差模型的变程和Kriging等值线图综合分析表明,喀斯特峰丛洼地常绿落叶阔叶混交林空间异质性研究的采样间隔10 m左右较适宜,但采样范围应大于10hm2,这对确定该区域动态监测样地的面积具有一定的指导意义。

Based on the vegetation investigation of 2 hm2 dynamic monitoring plot of karst mixed evergreen and deciduous broadleaf forest in Mulun National Nature Reserve in Guangxi,we analyzed spatial heterogeneity,fractal characteristics,and patterns of vegetation by using geostatistics and fractal theory and methods.A probe was taken into the maintenance mechanism through the analysis of nine variables（four diversity variables and five community structural variables）.The results showed that species number and four structural variables（density,average crown breadth,coverage,and conspicuousness） were moderate,but with larger variation coefficient ranging from 48.37% to 71.01%.While the variation coefficient of diversity index（Shannon-Wiener index,Simpson index and evenness） ranged from 5.49% to 22.64%,indicating that the forest community was diverse and stable.The variables except evenness displayed different degrees of spatial autocorrelation.The determined coefficient（R2） of the best models ranged from 0.900 to 0.982.The values of C/（C0＋C） and of fractal（D） were ranging from 0.582 to 0.827,and from 1.738 to 1.871,respectively,which implied that medium or high spatial dependence existed.The autocorrelation scale of density,average crown breadth,and average height was smaller than other variables,which suggested that the distribution,formation,and process of the three individual indexes determined the spatial pattern of the whole forest vegetation.Kriging contour maps of vegetation illuminated the differences of disturbance,topography,and soil environment quality.It is concluded that it would be feasible the sample interval of 10 m and the sample scale more than 10 hm2 for study on spatial heterogeneity of karst mixed evergreen and deciduous broadleaf forest,which would be help to determine the size of dynamic plot in the region.