陕南马尾松种群结构与动态的初步研究

A PRELIMINARY STUDY ON THE POPULATION STRUCTURE AND DYNAMICS OF PINUS MASSONIAN IN SOUTHERN SHAANXI

马尾松是陕南森林群落演替过程中的先锋树种，但在山坡中上部及山脊等立地条件较差的生境中能够形成稳定的群落。其稳定性表现在两个方面：（１）时间上——年龄结构呈倒Ｊ型，即拥有众多的幼苗幼树和少量上层木；（２）空间上——个体分布格局，即同龄个体所组成的斑块间的交替更新；这种稳定性属于地域性特征。

Southern Shaanxi is the edge region of distribution of Pinus massoniana,the population structrure and dynamics of Pinus massoniana possess both zonality and regionalism characteristic. And it often plays a pioneer role in succession series, but the population can form rather stable and persistent communities in some special habitats such as upside of the hillslope or ridges. The stability can be showed in two features :(1)age structure shows a reversal J type a lot of seedlings and some overstories are included;(2)spatial patern crumb that are composed of evenage individualities regenerate interchageably. Intraspecific strtiggle(self thining)is the main factor causing the dynamics of population structure.