神农架地区锐齿槲栎种群结构与更新的研究

POPULATION STRUCTURE AND REGENERATION OF QUERCUS ALIENA VAR. ACUTESERRATA IN SHENNONGJIA

锐齿槲栎 (Quercus aliena var. acuteserrata)林是神农架地区一种重要的落叶阔叶林 ,分布广泛 ,保存较好。通过对锐齿槲栎种群大小结构的研究发现 ,中等大小的锐齿槲栎个体数量较多 ,幼苗与幼树的数量在不同样地间变化很大 ,其大小结构分布图中多有一定程度的缺失。锐齿槲栎种群多呈现聚集分布 ,不同的尺度下其聚集程度不同。在每一个尺度下 ,幼苗幼树的聚集程度要比相同尺度下成体的聚集程度高。幼苗更新是锐齿槲栎更新的一种主要形式 ,其幼苗的出现与林窗的形成有密切的关系。在锐齿槲栎幼苗成长为幼树的过程中 ,由于种内与种间竞争的影响 ,导致了许多幼树的死亡。正是由于林窗形成等干扰因素的影响才使锐齿槲栎幼树得以进入群落上层。

This paper focuses on the structure and reg eneration of Quercus aliena var. acuteserrata populations in the Shennon gjia area of Central China. These populations are widely distributed and well co nserved. Analysis of size structure and spatial distribution pattern shows: 1) t he number of seedlings (height<1 3 m) and saplings (height 1 3-4 m) differs b etween plots, while the number of individuals in middle size classes exceeds tha t of larger size class; the lack of individuals at some size class is a common f eature of plots; 2) seedlings, saplings and adults all showed clumped distributi ons, and the degree of patchiness varied with the grid size analyzed; clumping w as stronger in seedlings and saplings than among adults; 3) Quercus aliena v ar. acuteserrata populations regenerate mainly via the production of seedlin gs. The appearance of which is closely related with the formation of gaps. The d ensity of seedlings and saplings was lower where shrub cover was high and many o f saplings died as a result of intraspecific and interspecific competition. Dist urbance, such as the formation of gaps, is important for saplings to enter into the upper layer of the community.