海岸林风害危险率评价的理论推导

本文在对间伐和风害之间关系的讨论和以往有关研究结果的基础上,确定了一种林木风害危险率的估计方法,用于评价间伐对林木风害的影响。这种对单株黑松及整个黑松林分的风害危险率估计,是根据风速廓线、枝条分布和透光分层疏透度(OSP)系数推导出来的。结果表明:如果枝条分布模型中的参数β等于单株树冠中风速廓线模型的衰减系数αs,参数H/D1.33可用于比较和评价对单株树木的风害危险率。这一原理也同样适用于整个林分,即用林分内风速廓线衰减系数α和透光分层疏透度(OSP)的分布中的衰减系数ν,结合D1.33估计和比较林分风害危险率。文中对间伐与非间伐单株黑松风害危险率进行了估计,得出了间伐两年后可以降低单株黑松风害危险率的结论;同时给出了确定林分风害危险率估计的过程图。图3参45。

Theoretical derivation of risk-ratios for assessing wind damage in a coastal forest

Based on the discussion of relationships between thinning and wind damage, and published information, a method for estimating risk ratios of wind damage was developed. Estimations of risk-ratio forPinus thunbergii trees and stands were deduced from stem bending theory and coefficients characterizing wind profile, distribution of branches and optical stratification porosity. The results showed that if the value of constant β in the branch distribution-model equals the attenuation coefficient α_s in the wind profile model for a single tree crown, then the parameter H/D_1.3 ³ (height over stem diameter cubed) can be used to compare and evaluate the risk-ratio of wind damage for individual trees. The same method can be applied to stands using the coefficient of wind profile in a stand, i.e. attenuation coefficient α, the coefficient from distributions of optical stratification porosity, i.e. extinction coefficient ν, and the parameter D_1.3 ³. The application of parameter H/D_1.3 ³ and the process of determining risk ratios of wind damage for stands were also given in the paper. Foundation item: This study was supported by Innovation Research Project of Chinese Academy of Sciences and the Ministry of Culture and Education, Japanese Government. Biography: ZHU Jiao-jun (1965-), male, Ph. Doctor, PhD advisor, Professor of Institute of Applied Ecology, the Chinese Academy of Sciences, China. Scholar researcher of Faculty of Agriculture, Niigata University, Japan. Responsible editor: Song Funan