基于主成分分析的小兴安岭低质林不同皆伐改造模式评价

Evaluation of Clear-Cutting Improvement Methods of Low-Quality Forests in Xiaoxing'an Mountains Based on Principal Component Analysis

由于多次过伐及自然灾害,使小兴安岭林区形成大面积郁闭度较低、林相衰败的低质林（杨学春等,2009;张泱等,2009）。为了恢复受损森林生态系统的功能、提高林分质量,对低质林分的改造势在必行。目前已提出很多低质低效林的改造模式,如抚育改造、带宽改造、择伐改造、复壮改造等（周立江,2004;孙洪志等,2004;庞学勇等,2005;马阿滨等,1995）,但关于如何评价改造模式的优劣还鲜有研究。评价不同改造模式的效果,选择何种指标是首先要考虑的问题。

Taking soil physical and chemical properties,water-holding capacity of litter,release of soil carbon as well as growth of regenerated species as index layer,principal component analysis was used for the comprehensive evaluation of improvement methods（horizontal clearcutting,vertical clearcutting,and forest gap）of low quality forests in Xiaoxing＇an Mountains area.The results showed that strip cutting performed better than the forest gap method.Within the strip cutting zones,horizonatal cutting had a better result than vertical cutting method.For the horizontal cutting zones,cutting strips with width of 6 m and 10 m achieved better results than the cutting strips with width of 8 m and 15 m.Within vertical cutting zones,the cutting strips of 6 m in width had the best result while no significant difference was noticed between cutting strips of 8 m and 15 m.The least improvement was noticed in cutting strips at 10 m in width.For the forest gap,small cutting area（25 m）had significant better result than the rest.