择伐对思茅松天然林乔木种间与种内关系的影响

Effects of selective logging on inter-and intra-specific interactions of trees in a natural Pinus kesiya forest

通过分析不同择伐强度下思茅松(Pinus kesiya)天然林乔木种群的生态位、种间联结、种内与种间竞争和群落稳定性,探讨干扰强度对思茅松天然林乔木种群种间与种内关系的影响。结果表明:(1)择伐干扰改变了大多数乔木树种在群落中的优势地位,思茅松优势地位未受影响,随着择伐干扰强度的增加,思茅松在群落中的生态位宽度逐渐变大,在重度干扰的群落中与红木荷(Schima wallichii)一起成为生态幅度最大的树种。(2)通过种间联结与生态位重叠分析发现,随着干扰强度的加剧,乔木种群的种间关系发生变化,中度干扰群落中物种之间的生态位重叠明显高于未干扰和重度干扰群落,而在三类群落中,思茅松与其他种群之间的重叠值较小。随着干扰强度增加,种群间正联结与负联结的种对所占的比例逐渐增加。(3)Hegyi竞争指数表明,三类群落中思茅松种群的竞争压力主要来自种间,而干扰强度进一步增加了思茅松种群的种间竞争强度,其种内平均竞争指数随着对象木胸径的增加而减少。(4)林窗是思茅松种群种间和种内关系变化的主要原因,三类群落都处于较不稳定的阶段,但中度干扰群落的物种丰富度与稳定性都高于未干扰和重度干扰的群落。择伐原则依据森林管理的目的而确定,如以木材培育为主或森林生态系统服务功能为主。

Aims Our objectives were to investigate the inter and intra-specific interactions of trees in a natural Pinus kesiya forest after three different selective logging disturbances, and to examine the impact of selective logging on disturbance intensity for sustainable forest management. Methods Niche breadth, niche overlap, interspecific associations, Hegyi＇s single-tree competition index model and M. Godron methods were used to analyze the inter- and intra-specific interactions of trees based on the field data collected from 81 small quadrats in nine plots in a natural P. kesiya forest in Jinggu County, Yunnan Province. Impottantfindings （1） Selective logging disturbance changed the relative dominance of most tree species ex- cept P. kesiya. The niche breadth of P. kesiya population increased with increases in disturbance intensity. The niche breadth was greatest in P. kesiya and Schima wallichii among all tree species under a severe disturbance. （2） The interspecific relationship of tree populations changed was affected by disturbance intensity. The niche overlap in the intermediate disturbance communities was apparently higher than those without disturbance or under a se- vere disturbance. In all the three communities, the niche overlap between P. kesiya and other tree species was very small. The proportion of species pairs with positive and negative associations became gradually increased with increases in disturbance intensity. 3） Hegyi＇s competition index showed that the main competitive stress of P. ke- siya population mainly came from inter-specific competition. Disturbance intensity increased the inter-specific competition between P. kesiya and other trees, and the mean competition index decreased with increasing diame- ter at the breast height in P. kesiya. 4） The formation of forest gap was the main reason for changes in inter and intra-specific relationships of P. kesiya forest. Although all communities were unstable under different disturbance intensities, species richness and community stability were both higher when under intermediate disturbance compared with no or severe disturbances. The principle of selective logging should be determined by the aim offorest management, which should be considered as the basis for timber production and forest ecosystem service.