中文摘要：

林隙径高比（DEG/H）是指林隙直径与林隙高度的比值。它是林隙的一个主要特征因子,是研究森林动态及评价森林采伐强度的一个重要指标。以关帝山三种天然次生针叶林（华北落叶松、云杉、油松林）林隙作为研究对象,分析了3种林分林隙径高比结构,结果为：云杉林林隙径高比DEG/H以0.6—1.6之间分布最多,占81.82%,油松林林隙径高比主要分布在0.8—1.6之间,占70.72%。华北落叶松林林隙径高比主要分布在0.4—1之间,占97.06%;通过林隙大小与林隙下幼树数量及林隙敏感度与幼树密度之间的散点分布趋势对林隙大小和林隙敏感度两个特征因子进行比较分析,结果为：林隙大小与林隙下幼树数量之间的散点分布无规律,很难反映各自林隙大小与幼树数量之间的具体关系。而DEG/H与幼树密度之间的散点分布很有规律,能较好的反映幼树密度与林隙径高比之间的关系;利用线性模型、对数模型以及二阶多项分布模型分别对幼树密度和DEG/H进行回归分析,并利用各自模型的相关系数、参数P值对它们进行比较,结果为：3种模型都可以用来拟合3种林分的幼树密度和林隙敏感度,其中对数模型拟合效果最好。

英文摘要：

Forest gaps are openings or holes created in forest canopy.Gaps may range in area from the openings created by the death of a single branch to larger scale blowdowmns by catastrophic or noncatastrophic disturbance.Usually the size of gaps was defined within the boundaries of the 4100m2.Forest gaps are divided into two kinds of gap,canopy gap and expanded gap.Based on the fact that forest gaps play an important role in the maintenance of tree species richness,thus it is useful to research the forest gaps for forest regeneration In this paper,the authors mainly analyzed the relationship between the diameter height ratio（DEG/H） and the number of young trees in gaps.The concept of diameter height ratio（DEG/H） is defined as the ratio of the gap diameter to gap height.It is a major feature factor of forest gaps,and is an important indicator for studying forest dynamics and evaluating forest harvesting. Based on three kinds of the natural secondary coniferous forest gap（Larix principis-rupprechtii,Picea spp,P.tabulaeformis） in Guandi Mountain in Shanxi Province,firstly the paper analyzed the structure of the forest gap using DEG/H.Second,the scatter distribution trends of gap size and DEG/H to the number of saplings were compared.Finally,linear model,logarithm model and second-order multinomial distribution model were used to analyze the saplings density and DEG/H,and to compare the models through the correlation coefficient and the P-value of parameters.The results are as follows： In the three kinds of the forest gap,the average size of diameter height ratio（DEG/H） of Picea spp is the biggest（average value=1.3327）,followed by Larix principis-rupprechtii（average value=1.1315） and P.tabulaeformis is minimum（average=0.7121）.DEG/H values of forest Gap for picea spp mainly are between 0.6 and 1.6,which reach 81.82%,P.tabulaeformis are between 0.8 and 1.6,which reach 70.72%,Larix principis-rupprechtii are between 0.4 and 1,which reach 97.06%. The scatter distributions of gap size and the number