华北落叶松和油松混交林林隙特征及更新研究
Forest Gap Characteristics and Regeneration of Larix principis-rupprechtii and Pinus tabulaeformis Mixed Forest

为深入了解燕山山地华北落叶松和油松混交林内林隙的形成特征及更新状况，对研究区域内固定样地进行了样线调查，测定样线所穿过林隙的大小、边缘木和形成木的特征以及林隙内更新苗高度及地径，并进行数据分析。结果表明，所调查的38个扩展林隙中，以40~60 m2的数量比最大，而100~120 m2的面积比最大，分别为23.68%和30.59%；大多数林隙形状近似于椭圆形，占总数的92.11%；林隙形成木共190株，其中有2个形成木的林隙最多，占林隙总数的 15.79%；林隙的形成木全为落叶松和油松，且基径＜25 cm的所占比例较大，占总数的90.53%；边缘木高度以15~17 m的个体最多，胸径主要集中在20~35 cm；林隙内不同区域更新苗密度差异不显著，苗木多分布于中心及过渡区域；林隙内不同地带苗木地径及树高均呈现出中心区域＞过渡区域＞边缘区域的趋势。
In order to deeply understand the characteristics and regeneration conditions of the gaps in Larix principis-rupprechtii and Pinus tabuliformis mixed forest in Yanshan Mountain, line transects method was used to examine the permanent sample plots in study area. The gap area, characteristics of gap border trees and gap makers, as well as the height and ground diameter of the trees were measured. The results showed that among the whole 38 extended gaps surveyed, maximum ratio of gap number (23.68%) was observed in those with the size of 40-60 m2, while the maximum ratio of gap area (30.59%) was found in 100~120 m2 size. Most gaps were close to the oval shape, accounting for 92.11% of the total. There were 190 gap maker trees in total, the number of the gaps with 2 makers was the most, accounting for 15.79% of the total. Gap makers were all L. principis-rupprechtii and P. tabuliformis, and the proportion of the gap makers with basal diameter less than 25 cm was the most, 90.53% of the total. Most individual border trees were in the height of 15-17 m, and in the diameter at breast height of 20-35 cm. Differences in the density of regenerated trees within the gaps in different regions was not significant (p＞0.05), but more trees were found in central and transition areas. Ground diameter and tree height were in the tendency of central zone＞transition region＞marginal area within a gap