珍稀濒危植物南方铁杉种群结构与空间分布格局研究

Studies on the Population Structure and Spatial Distribution Pattern of Tsuga chinensis var. tchekiangensis

为了揭示南方铁杉的种群特征,在九龙山自然保护区南方铁杉主要分布地设置400 m2样方10个,以种群年龄结构和存活曲线分析南方铁杉种群的基本数量特征,应用扩散系数、丛生指标、聚块性指数、平均拥挤度指数、负二项式分布参数、Cassie指标6种聚集强度指数和Greig-Smith和Kershaw 2种格局规模分析方法确定不同年龄阶段、不同空间尺度下的南方铁杉种群空间分布格局。结果表明:不同样地南方铁杉种群年龄结构存在一定差异,但不同种群均表现为增长型,幼年阶段的个体较丰富,成年个体数量相对较少;不同年龄阶段种群,空间分布格局差异主要体现在:幼苗和幼树阶段都为集群分布,中树和大树向随机分布发展;不同区组大小的南方铁杉种群分布格局不同,但在不同样地之间差异不明显,南方铁杉种群的聚块规模大体为8 m2和32 m2;种群环境因子的主成分分析结果表明,岩石裸露率、土壤有机质含量、郁闭度和土壤水分含量是影响南方铁杉种群结构和空间分布格局的最重要因素。

10 plots of 400 m^2 in Jiulongshan Nature Reserve were established and investigated to reveal population characteristics of Tsuga chinensis var. tchekiangensis in Zhejiang province. Basic quantitative characteristics of the population were analysed by age structure and survival curve. At the same time, spatial distribution pattern and dynamics of the population of different ages and spatial scale were studied by six aggregation intensity indexes, such as dispersion index, clumping index, patchiness index, mean crowding index, negative binomial parameter and Cassie＇s index, and two pattem scale analysis methods of Greig-Smith and Kershaw. The results showed that T chinensis var. tchekiangensis communities had different age structures, but different populations had the only pattern of growth： abundant saplings less adults. Spatial distribution pattern of the population at different ages had characters like clumped distribution for seedlings and saplings, while random distribution for adults. Different plots had siguificant diffrerence of the population distribution pattern. Clumped area of the population was 8m^2 and 32 m^2 by Greig-Smith＇s and Kershaw＇s mean variance analysis. Pminciple environmental componment analysis demonstrated that rocky percentage, organic matter content in the soil, closure of the forest and moisture content in the soil had great effect on population structure and spatial distribtion pattern.