采用理论分析、建立数学模型、案例研究验证相结合的方法,系统研究针阔混交林冬季择伐作业中油锯伐木对保留树木损伤率的影响。首先,通过理论分析,建立保留木损伤率与择伐强度、采伐木单株材积及初始林分密度的理论数学模型; 其次,利用在黑龙江省带岭林业局东方红林场实地观测得到的数据,进行案例研究,并对模型进行验证和修正。结果表明: 模型模拟数据与实际观测结果相关性较好,模型有效。经过研究,得出保留木损伤率与择伐强度呈抛物线关系,与采伐木单株材积和林分密度的乘积呈线性关系,并利用调查数据模拟出保留木损伤率与择伐强度、采伐木单株材积和林分密度乘积的三维立体曲面图; 人为控制采伐木倒向对降低保留木损伤率效果显著(损伤率最大值相对降低9%)。最后,根据研究结果,提出若干降低保留木损伤率的作业建议。
How to decrease the damage rate of residual standing trees in the selective cutting sites is quite important for forest land owners to reduce the wood production waste and to develop and utilize forest resources in a sustainable way. The damage rate of residual standings in a selective cutting site with conifer-broadleaved forest in Xiaoxing’anling Forest Region, which was caused by chainsaw felling operations, was studied through modeling analysis and case study. At first, after the theoretical system analysis for influencing factors according to data, the mathematical modeling(RDM)was established, which described the impacts of harvesting intensity(HI), the initial stands density(SD)and stem volume of each tree planned to be cut down(VTPC) to the damage rate of residual standing trees(DRRT)in the operation sites. Secondly the theoretical model was tested, verified and validated by a practical case study in Dongfanghong Forest Farm of Dailing Forestry Bureau in Xiaoxing’anling. The research results showed that the model(RDM)was valid with high correlation between two group data for describing DRRT and HI, SD and VTPC, e.g. one group from modeling simulation and another one from case study site survey. The results also indicated that DRRT was changed following HI in a parabola curve and following the time of SD and VTPC in a linear trend,and the three-dimensional(3D)curve surface for describing DRRT and HI, SD and VTPC was simulated according to survey data. The case study demonstrated that the loggers could decrease the DRRT around 9% by controlling the tree felling direction. At last the suggestions for reducing DRRT have been proposed according to the modeling analysis and case study results.
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