台风“布拉万”对东北近天然落叶松云冷杉试验林的影响

台风是重要的森林干扰因子之一,会对森林生态系统的结构和功能产生较大的影响。2012年的台风"布拉万"对我国东北地区局部森林造成了严重的破坏。以受灾最重的吉林省汪清林业局的近天然落叶松云冷杉林为对象,采用方差分析和相关分析方法,研究林分结构和地形条件对林木株数损伤率的影响。结果表明:(1)林木损伤类型可分为折断、连根拔起、搭挂、压弯4种,其中连根拔起为最主要的损伤类型,占总损伤株数的52%,台风灾害造成的林木株数损伤率平均为14.09%。(2)径级大小对林木株数损伤率的影响显著。损伤主要发生于径级较小林分处,径级越大,其株数损伤率越小。(3)林木株数损伤率随林分密度的增加有减小的趋势,但在统计学上它们的关系不显著。(4)不同树种间的林木株数损伤率差异显著,落叶松、冷杉等针叶树种损伤株数最多。(5)林分的树种多样性指数与林木株数损伤率无显著的相关性。(6)海拔、坡度和坡位对林木株数损伤率的影响不显著,但坡向的影响显著,东北坡向林分的林木株数损伤率最大。研究结果可以为灾后森林恢复和减少风灾影响的森林培育措施提供依据。

The influence of typhoon Bolaven to semi-natural larch-spruce-fir forests in northeast China

Typhoons are one of the most important natural disturbances, which directly or indirectly have effects on forest stand structure and function. Typhoons disturbance events occur in nearly all forest ecosystems and have profound impacts on forest structure, species diversity and ecosystem functions. Such ecological effects are often complex, subtle, and at small scale relatively unpredictable. Many factors such as tree size, stand density, tree species, stand structure, altitude, gradient, slope location and aspect, affect wind resistances of tree species and the extent of forest damage. The typhoon rarely arrives in temperate regions close to the coastline and in the temperate regions of the interior land. So there is little known about the influence of typhoon on forest in the temperate regions of the interior and even in northeast China. Typhoon "Bolaven" has caused serious damage on forests in northeast China in 2012. In this paper, Typhoon-induced damage has been analyzed at stand level for semi-natural larch-spruce-fir forests of Wangqing Forestry Bureau in Jilin Province. Analysis of variance and correlation analysis are used for examining effects of stand structure and topography on damage severity of trees. Results showed that:(1) Typhoon caused massive damage to semi-natural larch-spruce-fir forests, in some cases reaching over 30% of all trees in the stands. The average percentage of the damaged trees was 14.05%. Major tree damaged types were uprooted, broken, hooked and bending. Among these types, the type of uprooted was the dominant one with a rate of 52%. (2) Tree diameter class had significant effects on the extent of tree damage. The medium and small-class trees were more vulnerable to typhoon damage than the bigger ones. (3) There was no significant correlation relationship between the density and the extent of tree damage. However, the extent of tree damage weakly decreased with increasing stand density. (4) Trees damaged differed significantly among tree species. Broad-leaved tree species were easier to be hurt by typhoon. (5) No significant correlation relationship was found between tree species diversity index and the proportion of damaged trees. (6)The altitude, gradient and slope location had no significant impacts on the extent of the tree damage, while the aspect had, especially the northeast aspect which was more vulnerable with a high damage rate of 18.35%. Therefore, tree size, tree species and aspect were important factors affecting the tree damage of typhoon in this study, and the impact was complicated. We suggested that improving tree quality and mixing tree species enhance stand resistance to wind. The findings presented in this study provide information that can be used to implement silvicultural practices to minimize the risk of those forests and to resist wind damages.