粤北天然林优势种群结构与空间格局动态

在粤北始兴县罗坝自然保护区以木荷、栲树和马尾松为优势的群落内 ,设置 10 0 0m2 样地 5个 ,应用相邻格子法进行每木调查获得野外资料 .通过对优势种种群结构和空间格局的研究 ,结果表明 ,木荷、栲树种群结构呈金字塔型 ,幼苗贮备达 15 3 8和 9763株·hm-2 ;种群从Ⅰ、Ⅱ级幼苗发育到幼树过程中死亡率较高 ;马尾松种群结构呈倒金字塔型 ,幼苗缺乏 ,幼树只有 4株·hm-2 ,但大树较多 ,达 44株·hm-2 ;在以常绿阔叶树种为主的针阔混交群落中 ,马尾松、栲树种群分布格局为均匀分布 ;在以针叶树为主的针阔混交林群落中 ,两者的空间分布格局为集群分布 ,但两者格局变化原因不同 ;木荷种群空间分布格局在上述群落中均表现为集群分布 ,但聚集强度不同 ,K值为 0 42 80～ 0 975 0 ;木荷种群在不同发育阶段其空间分布格局没有较大差别 ,总体上都是集群分布 .栲树种群在不同发育阶段空间分布格局差别较大 ,除大树是均匀分布外 ,幼树、中树均趋于集群分布 ;马尾松种群分布格局中仅中树为集群分布 ,而幼树与大树均为均匀分布 .不同种群在不同发育阶段空间分布格局的差异与其生物学和生态学特性密切相关 .不同区组对种群空间分布格局产生影响 .

Structure and spatial pattern dynamics of dominant populations in a natural forest in north Guangdong Province

Five 1000-m2 plots were set up in a forest dominated by Schima superba, Castanopsis fargesii and Pinus massoniana in Luoba Nature Reserve, Shixing County, north Guangdong Province. Field data were obtained by tally with contiguous grid quadrat method. The analysis of population structure and spatial distribution patterns of the dominant species in the forest shows that S. superba and C. fargesii had a large reserve of seedlings, with up to 1538 and 9763 seedlings per hm2, respectively, showing a pyramid shape of population structure. Both populations had a high mortality for seedlings of classes I and II in the process of development to saplings. The population structure of P. massoniana was an inverse pyramid type, with no seedlings and only 4 saplings per hm2, but 44 large trees per hm2. The spatial distribution patterns of P. massoniana and C. fargesii in coniferous broadleaved mixed community chiefly dominated by broadleaved trees were uniform, and in those chiefly dominated by P. massoniana were aggregated, but there were different causes of pattern dynamics for P. massoniana and C. fargesii. S. superba in both communities showed an aggregated distribution pattern. The aggregation intensity was different, with K values from 0.4280 to 0.9750. Regarding the distribution patterns in different development stages, S. superba was aggregated in different stages, while C. fargesii varied with uniform distribution pattern for the large trees and aggregated distribution pattern for the saplings and median trees. As for P. massoniana, its median trees showed an aggregated distribution pattern, while both the saplings and large trees were uniform. The variations in spatial distribution patterns of populations in different development stages were closely related to the biological and ecological characteristics of the species, but different block size had an impact on the outcome of spatial distribution patterns.