中文摘要：

以南岭自然保护区不同海拔高度的乔灌木样方为研究对象，利用空间代替时间的方法，研究林分自然稀疏规律和植物个体大小与密度的关系及其对海拔高度变化的响应机制。结果表明：1）群落尺度上也存在着自然稀疏规律，乔木群落的自然稀疏指数为-1.305 6，灌木为-1.298 9，符合Enquist提出的-4/3自疏法则。2）随着林分密度的增大，乔木样方的平均冠幅与树高都明显减小，灌木样方的平均冠幅减小，植株高度变化则不明显。3）随着海拔高度变化，乔灌木的个体大小对其作出不同的响应。在自然稀疏表达式中，系数k的大小随海拔高度变化而变化，海拔高度越高，k值越小。其中乔木样方的k值变化幅度大，灌木样方幅度小，表明海拔高度变化对乔木个体大小的影响更大。

英文摘要：

Self-thinning is a hot issue in ecological theoretical research, however, because of the long growth period and complex process in self-thing, relative research in woody plants’ self-thinning rule is very few and still no consensus has been reached up to the present. The research used natural phytocoenosium quadrat in different altitudes in Nanling nature protection area as the material to study the woody phytocoenosium’s self-thinning rule by means of spatial-temporal substitution and to analyze the relationship between space size and density, in addition, we discuss how their crown diameter and plant height response to the altitude change. The results showed that： 1） The self-thinning rule is also suitable to the natural woody phytocoenosium. The self-thinning exponent of arbor phytocoenosium is -1.305 6 and that of shrub phytocoenosium is -1.298 9, which are in accord with Enquist’s -4/3 self-thinning rule. The main reason may be that, Enquist put forward the -4/3 self-thinning rule at the point of the relationship between plants’ growth’s resource need and density. In this research we regard the plants’ living room as the biomass, which reflects how much resource that the plants gain. 2） Woody plants’ size and density have close correlation. When the density increases, both the average crown diameter and tree height reduce obviously in arbor quadrat, similarly, in Shrub quadrat the average crown diameter reduces, whereas, the plants’ height does not change obviously. In this research, it is shown that the crown diameter in the arbor phytocoenosium that live under altitude 900 m plays an important role in self-thinning process, in the phytocoenosium living between altitude 900 and 1 300 m, the plant height plays an important role in self-thinning process, and when the altitude is over 1 300 m, survival pressure plays a leading role in self-thinning process. Differently, in shrub communities, crown diameter plays a leading role in self-thinning process in different altitudes. 3） Arbor an