亚热带常绿阔叶林锥和木荷枯立木点格局分析

Spatial Point Patterns of Snags of Castanopsis chinensis and Schima superba in a Subtropic Evergreen Broad-leaved Forest

  • 摘要: 在广东省康禾自然保护区10 hm2常绿阔叶林样地中,设置1 000个样方调查枯立木,选取主要树种锥及木荷运用单变量成对相关函数g(r)函数进行个体点格局分析,采用标记相关函数kmm(r)以枯立木胸高断面积为标记进行标记点格局分析,探究枯立木空间分布格局的形成原因。结果表明:锥和木荷枯立木个体径级结构均表现为“L”型,小径级个体死亡多,随着径级的增大,死亡个体数减少。锥枯立木个体空间分布格局在0~50 m尺度下表现为聚集分布,随着尺度的增大,聚集程度降低;木荷枯立木个体空间分布格局在0~4.3 m以及8.7~14.0 m时表现为聚集分布,4.4~8.6 m以及14.1 m后均表现为随机分布。锥及木荷枯立木同种个体间无显著相关性,表明同种枯立木在死亡前个体间无竞争作用。枯立木个体在生长发育早期死亡较多,其空间分布格局的形成可能主要是受活立木种子的扩散限制、密度制约和生境过滤的多重影响,而大径级枯立木主要是由于自然衰老导致其死亡。

     

    Abstract: We established 1000 quadrats in 10 hm2 subtropic evergreen broad-leaved forest located in the Guangdong Kanghe Provincial Natrue Reserve. Using spatial point pattern analysis and marked point pattern analysis with dominant species of Castanopsis chinensis and Schima superba, we determined the spatial point pattern of individual and basal area to explore the formation of spatial patterns of snags. The results showed that the most snags of C. chinensis and S. superba were those with small DBH, and the abundance of snags decreased with the DBH increased. The snags of C. chinensis showed an aggregated distribution at the scale of 0−50 m, and the aggregation declined as the scale enlarged; the snags ofS. superba showed randomly distribution at the scale of 4.4−8.6 m and 14.1−50 m, and aggregated at local scale of 0−4.3 m and 8.7−14.0 m. The basal area ofC. chinensis and S. superba showed that sangs were independent, which indicated no competition among snags. C. chinensis and Schima superba died more in their early stages. The formation of snags of these two species might be influenced by dispersal limitation of seeds and density dependence as well as environment filter, the lager trees might die because of intrinsic aging.

     

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