濒危植物元宝山冷杉种群结构与分布格局

Study on the Structure and Spatial Pattern of the Endangered Plant Population of Abies yuanbaoshanensis

元宝山冷杉是广西特有、列入《中国植物红皮书》的珍稀濒危植物 ,种群数量不足 90 0株。在元宝山自然保护区设置5块样地 ,应用相邻格子法进行调查获取野外资料。对元宝山冷杉种群进行统计 ,编制种群的特定时间生命表、绘制大小结构图和存活曲线 ,并进行种群动态谱分析 ;应用理论分布模型和聚集强度指数进行种群分布格局分析。结果表明 :元宝山冷杉种群幼苗个体比例大 ,小个体级死亡率较高。个体胸径超过 2 1 cm后 ,生命期望陡降。谱分析表明 ,种群的动态过程存在周期性。由于种内和种间竞争的影响及林窗效应 ,种群结构有波动性变化过程 ,元宝山冷杉种群当前仍为稳定型种群。元宝山冷杉种群呈现聚集分布 ,在不同发育阶段的分布格局有差异 :幼苗、幼树阶段为集群分布 ,中龄阶段向随机分布发展 ,大树呈均匀分布。种群在不同发育阶段的空间分布格局差异与其生物学和生态学特性密切相关 ,同时受群落内小环境的影响。

Abies yuanbaoshanensis is an endangered evergreen conifer endemic to Guangxi, and listed in the Red Data Book of plant in P.R.C., with less than 900 individuals remaining on earth.5 plots were established in Yuanbaoshan Nature Reserve, and field data were obtained by tallying with contiguous grid quadrate method. The time specific life table, survivorship curve and size structure of Abies yuanbaoshanensis population were analyzed and a spectral analysis of the population dynamic was made in this paper. The results showed that size distribution of the whole population generally fit the reverse “J' type and had a stability structure, majority of the individuals were seedling. The survivorship curve indicates that the mortality is high at the younger stage than in others. The expected average life largely decreased for Abies yuanbaoshanensis population after DBH >21cm. Spectral analysis shows an obvious periodic fluctuation existed in the population. In the stage of the mature forest, the structure of the Abies yuanbaoshanensis had a process of fluctuation accompanying the regeneration or rehabilitation through forest gaps. Although, the spatial patterns of Abies yuanbaoshanensis population differed at various developmental stages, the general was clump: clump for seedlings and saplings, random for adult trees and even for big trees respectively. These differences at various developmental stages were related to their biological and ecological characteristics and microenvironments.