Abstract:

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.

Key words: low-quality forests, improvement methods, principal component analysis, comprehensive evaluation