缙云山马尾松种群数量动态初步研究

 马尾松(Pinus massoniana)种群是我国亚热带森林植被演替的先锋种群之—。研究其数量动态对亚热带森林群落和生态系统的研究有着重要意义。“样地编年序列”的应用为长命多年生植物种群数量动态的研究提供了一条捷径。缙云山马尾松种群，约在7龄前，其密度随时间而增长，其后降低。其间关系可用下式近似表达：(07)， 式中，D是种群密度估计值，A是种群年龄。缙云山马尾松种群生物量在灌草从到松阔混交林初期的演替中呈现Logistic增长。符合公式：式中，Bp是种群生物量的估计值，A，e是自然对数的底。在从混交林到常绿阔叶林的演替中，其生物量表现出随时间下降的趋势。在自疏过程中，马尾松种群平均植株生物量与种群密度服从-3/2稀疏定律。符合公式：式中，Bi是平均植株生物量，D是种群密度。导致缙云山马尾松种群数量动态变化的动力，主要是种内光资源竞争引起的自疏和种间光资源竞争引起的他疏。

A PRELIMINARY DEMOGRAPHIC STUDY OF PINUS MASSONIANA AT JINYUN MOUNTAIN, SICHUAN PROVINCE

Masson pine (Pinus massoniana) is one of the pioneer species of the subtropic forest succession and of all the secondary succession stages on, the Jinyun Mountain,which is situated in the northwest of Beipei district Chongqing city, Sichuan Province (29?50′N,106?26′E). The study on the quantitative dynamics of Masson pine population is of great significance for studying the forest communities and ecosystems in subtropic China.The use of the plot-chronosequence provides a short-cut method for studying the population dynamics of long-lived plant species. Bfore the age of seven, the density of a Masson pine population in the mountain increases and the rate of its growth decreases with the passage of time. And beyond that age, the density decreases and the rate of growth increases with the passage of time. The density would continue to decreases even after 30 years, but the rate of growth would increase markedly with the lapse of time.In the period between shrub-grassland and Masson pine forest, the dynamics of population biomass shows a logistic growth, i.e. where A is the population’s age in years Bp is estimation of the population biomass in t.ha-1. In the period between the coniferous broad-leaved mixed forest and the evergreen broadleaved forest, the population biomass decreases with the time passed. The relationship between the populational density and the mean plant biomass during the self-thinning accords .with t he-3/2 thinning power law and can be described as,where, Bi is mean plant biomass in kg, D, populational density in trees.ha-1. The obvious factor resulting in the quantitative dynamics of Masson pine population at the mountain is the self-thin-ning caused by intraspcoific competition and the alien-thinning by interspecific competition for the light resource in the stand.