关帝山天然次生针叶林林隙径高比

林隙径高比(D_EG/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D_EG/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D_EG/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D_EG/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。

The forest gap diameter height ratio in a secondary coniferous forest of Guan Di Mountain

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 4 100m². 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 (D_EG/H) and the number of young trees in gaps. The concept of diameter height ratio (D_EG/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 D_EG/H. Second, the scatter distribution trends of gap size and D_EG/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 D_EG/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 (D_EG/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). D_EG/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 of saplings are not regular, it is difficult to reflect the specific relationship between the gap size and the number of saplings. However the scatter distribution of gap diameter height ratio and the density of saplings are very regular, it is easy to reflect the relationship between gap size and the number of saplings. From the scatter distribution of gap diameter height ratio and the density of samplings, we can include that there is a positive correlation between the number of young trees and D_EG/H. According to analysis of the linear relations between the diameter height ratio of expanded gap and the seeding density, the results demonstrated that Larix principis-rupprechtii has the most obvious positive correlation, followed successively by oil pine and spruce forest. The saplings density and D_EG/H were analysed based on the linear model, the logarithm model and the second-order multinomial distribution model. The results showed that the regression relationship of the three kinds of model are very significant for two significance levels 0.05 and 0.01, thus all of the three models can be used to fit the relationship between saplings density and D_EG/H in those three kinds of forest. The solution of the logarithm model is the best by using the correlation indicators of the coefficient and the P-value for each model.