格氏栲天然林林窗边界木特征研究

Study on the characteristics of gap border trees in Castanopsis kawakamii natural forest

对格氏栲天然林林窗边界木的树种组成、胸径结构、高度结构和偏冠率进行了研究。结果表明:格氏栲天然林林窗边界木主要组成树种为格氏栲,所占比例为74.75%;林窗边界木胸径结构为尖峰呈左偏,符合正态分布、Weibull分布和β分布;边界木高度级结构呈正态分布,主要集中在15-30 m;林窗边界木存在明显的偏冠现象,仅有5.05%未出现偏冠现象,边界木的偏冠率主要在0.5-0.8之间(70.71%),不同树种间的偏冠率没有显著差异。林窗边界木大部分由发育良好的中、高径级树木组成,与林下相比林窗边界木大部分已过熟,仅存较少小径级的边界木,表明依靠林窗边界木完成林窗更新存在困难,需加强对林窗幼苗和幼树的保护,实现林窗更新。

The main structural characteristics of gap border trees（GBT） of Castanopsis kawakamii natural forest,which consisted of the main tree species,structure of diameter at breast height（DBH）,structure of tree height and ratio of crown inclination（RCI）,were investigated.The results showed as follows： the main tree species of GBTs were C.kawakamii whose proportion was 74.75%;the structure of DBH of GBTs showed a left-skew distribution,which was also consistent with the normal distribution,Weibull distribution and β distribution;the structure of tree height classes showed a normal distribution mainly from 15 to 30 m;the GBTs′ crown inclination was obvious,only 5.05% of GBTs regularly crowned,and the RCI of GBTs was mainly from 0.5 to 0.8（70.71%）.Moreover,the differences of RCIs of tree species were insignificant.With exception for a few low diameter GBTs,most of GBTs were composed of well-developed medium or high diameter trees which were over mature compared with those of understory,which indicated that it was difficult to accomplish the forest gap regeneration by solely relying on GBTs and it was indispensable to strengthen the protection of seedlings and young trees.