青海云杉不同龄级立木的点格局分析

Spatial pattern analysis of individuals in different age-classes of Picea crassifolia

本文以祁连山优势种群青海云杉作为研究对象，在天老池小流域典型地段设置一个100mX701TI的样地，采用点格局分析法分析其不同龄级的空间分布格局和空间关联性。结果表明：（1）青海云杉的年龄结构相对比较稳定，呈弱增长型；（2）龄级1个体在不同空间尺度下都表现出明显的集群分布；龄级Ⅱ个体，在0—31m尺度内呈集群分布，在大于31m的范围内趋于随机分布；龄级Ⅲ个体，除在6～24m范围内呈集群分布外，在其余空间尺度都表现为随机分布。随着青海云杉龄级的增大，其空间分布格局逐渐趋向于随机分布。（3）龄级I和龄级Ⅱ个体，在0～20m呈显著的负关联，在20～23m其关联性减弱，大于23m时趋于正关联；龄级I和龄级Ⅲ个体，在所有尺度下均呈显著负关联；龄级Ⅱ和龄级Ⅲ个体，在所有尺度内都表现出负关联性。基于低龄级个体数量多且在小尺度上呈聚集分布的现状，从长远角度考虑，应适当对其进行疏伐，以此来扩大其生存空间，减小生存压力。

A plot （ 100 rex70 m） of Pieea erassifolia stand was set up in Tianlaochi catchment of the Qilian Mountains, to analyze the spatial distribution pattern of different age classes and the spatial correlation based on point pattern analysis. The results showed that ： （ 1 ） The age struc- ture of P. crassifolia was relatively stable, being in a slight growing trend. （2） The age-class Ⅰ showed aggregated distribution at different spatial scales; the age-elass Ⅱ showed aggregated dis- tribution within 0-31 m, while showed the random distribution at 〉31 m scale. An aggregation distribution pattern was found at scales from 6-24 m, and random distribution patterns at the oth- er scales for the age-class Ⅲ individuals. On the whole, the spatial pattern showed random distri- bution with the increase of P. erassifolia＇ s age. （3） The correlation between the age-class I and the age-class Ⅱ was significantly negative at 0-20 m spatial scale, gradually weakened at 20-23 m, but became positive over 23 m. The age-class I and age-class Ⅲ individuals presented sig- nificantly negative correlations at all spatial scales. Age-class Ⅱ and age-class Ⅲ individuals showed negative correlations at any scale. Based on the large number and gathered distribution of young individuals at a small scale, we should take thinning to reduce the survival pressure and expand living space of remaining individuals, from a long-term perspective.