西南亚热带典型天然常绿阔叶林的空间结构特征

以西南亚热带分布较广泛的两种典型的天然常绿阔叶林——四川大头茶林和栲树林为研究对象,根据树种组成,采用混交度、大小比数和角尺度3个空间结构参数,对比分析2种林分的空间结构特征。结果显示:(1)四川大头茶林和栲树林群落的乔木层分别有8和9个树种,2种林分内的优势种的密度及每公顷断面积优势明显。(2)2种林分的树种混交程度较高,林分平均混交度分别为0.61和0.73,混交程度均在中等以上;栲树林群落的树种隔离程度优于四川大头茶林;林分内的平均大小比数分别为0.47和0.45,多数林木处于中庸状态,林分内不同径级的林木在各组成的空间结构单元内分布比较均匀。(3)四川大头茶林的平均角尺度为0.523,属于聚集分布;栲树林的平均角尺度为0.517,属于随机分布,且呈现轻微的聚集分布。研究表明,两种林分的混交度差异显著,而大小比数和角尺度差异不显著,栲树林较四川大头茶林的群落结构稳定。

Spatial Structural Characteristics of Typical Natural Evergreen Broad-leaved Forest Features of Southwest Subtropical Area,China

Taking two typical widely distributed natural evergreen broad-leaved forest-Polyspora speciosa forest and Castanopsis fargesii forest in southwest subtropical as object,we analyzed their spatial structure characteristics with three space structure parameters including mixed degrees,the number and angular size scale according to species composition.Results indicated that:there were 8 and 9 kinds of species in the arbor layer of the P.speciosa forest and C.fargesii forest.The two stands had the advantages in dominant species density and basal area per hectare.The average mingling degree of the two forests were above the middle mingling degree,0.61 and 0.73,respectively.The species segregation of C.fargesii forest communities was better than that of P.speciosa forest.The average neighborhood comparison values of the two stands were 0.47 and 0.45,respectively,which indicated that the majority of trees were in a moderate state.Trees in different diameter classes were distributed uniformly in the spatial structure of the constituent unit.The average uniform angle index was 0.523 in the P.speciosa forest,being aggregated distribution,while 0.517 in the other stand,being randomly distribution with slightly aggregated distribution.The mingling degree of two kinds of forests had significant differences,while the differences between the neighborhood comparison and uniform angle index were not significant.It can be concluded that C.fargesii forest has more stable community structure than P.speciosa forest.