长苞铁杉林林隙物种更新动态的初步研究

Studies on Species Regeneration Dynamics of Tsuga longibracteata Forest Gaps

采用扩散系数C、聚集度指标I、扩散指标Iδ、平均拥挤度M*、聚块性指数PAI和聚集强度K对不同发育阶段及不同大小级林隙中长苞铁杉幼苗分布格局的测定结果表明:在林隙发育的前、中期长苞铁杉幼苗在林隙中呈聚集分布,而在林隙发育的后期为随机分布,但在不同大小级的林隙中,长苞铁杉的分布格局并无差异;随林隙的不断发育,长苞铁杉幼苗在林隙中的密度依次降低,在林隙发育的前期密度最大,中期次之,到林隙发育的晚期密度最小,且在较大的林隙中密度较大。

Six indices（ C, I, M^＊ , PAI, K） were used to analyze the spatial distribution patterns of Tsuga longibracteata seedling in gaps of different phase and different size. The results showed that the seedlings were clumped in the early phase gaps and middle phase gaps , and the distribution of seedlings in the late phase gaps were random. However, the Tsuga longibracteata seedlings in the gaps of different sizes showed no difference in distribution, the distribution patterns were all random. The density of the Tsuga longibracteata seedlings in the gaps was affected heavily by gap phase and gap size. It declined with the development of gaps, that is： the density in the early phase gap 〉 that in the middle phase gap 〉 that in the late phase gap, and the density increased with the expansion of the gap size.