江西武夷山南方铁杉原始林空间结构特征分析

Analysis of the Spatial Structure of Tsuga chinensis var.tchekiangensis Virgin Forest in Jiangxi Wuyishan National Nature Reserve

为明晰南方铁杉的龄组多样性、空间结构特征及其演替趋势,以传统林分因子及丰富度指数、Simpson指数、Shannon-Wiener指数、Pielou均匀度指数4个多样性指数为基础,结合混交度、角尺度、大小比数、开敞度4个林分空间结构参数对江西武夷山南方铁杉原始林进行综合分析。结果表明,乔木层共包括62个树种,南方铁杉重要值高居首位,是乔木层的建群种和优势种;混交度均值为0.64,属强度混交;南方铁杉在空间结构单元中以优势木为主;角尺度均值为0.64,为较低程度的聚集分布;开敞度均值为0.11,生长空间严重不足。通过各样带间的比较,发现南方铁杉在1790~1810m海拔范围内结构最为合理,其空间结构特征表现为混交度、大小比数、角尺度均较为稳定,龄组结构特征表现为各龄组比例合理且成熟林龄组株数达到最大。南方铁杉的龄组结构分布连续,在该原始林的林分空间结构中占据有利的生态位,种群更新能力因海拔差异而不同,可以预见,其分布有向中等海拔地区集中的趋势。

To investigate the age-group diversity,the spatial structure and the succession trend of Tsuga chinensis var.tchekiangensis in Jiangxi Wuyishan National Nature Reserve.Four spatial structure indices (i.e.mingling,angle index,neighborhood comparison and opening degree)together with several traditional indices (e.g.species composition,diameter at breast height)and four diversity indexes (i.e.species richness,Simpson index,Shannon-Wiener index and Pielou evenness index)of the forest were measured and analyzed.The results showed that:The forest was composed by 62 tree species and T.chinensis var.tchekiangensis was the major dominant species,whose importance value was the highest.The forest was highly mixed at whole stand level,manifested by an average mingling degree of 0.64.T.chinensis var.tchekiangensis composed the majority of dominant trees in the spatial structural units.The horizontal pattern of the stands displayed a low degree of aggregative distribution,with a uniform angle index of 0.64.The growing space for most trees in the forest was severely insufficient,indicated by an average opening degree of only 0.11.By comparing with all the belt transects,it showed that its age-group and spatial structure in the altitude of 1 790-1 810 m was the most reasonable.Its spatial structure characteristics showed that mingling,neighborhood comparison and angle index were more stable,and the structure characteristics of the age group was reasonable and the number of mature age-group reached the maximum.Age-group structure of T.chinensis var.tchekiangensis was continuous.It occupied a favorable niche in the stand space structure of the virgin forest and its ability to update was different due to various elevations,so there existed a tendency that its habitat offset to the middle elevation areas.