The influencen of stand state on the occurrence ofDendrolimus superans (Butler) in Daxing’an Mountains

Abstract

Dendrolimus superans (Butler) occurred in the vast areas of Daxing’an Mountains forest, in Heilongjiang Province, in 1990. Stands damaged byI). Superans seriously, intermediately and lightly show patch shape distribution within damaged area. By ordination analysis and correlation analysis between ordination factors and coordinate axis. It was found that occurrence ofD Superans in different extent is owing to the effect of forest age, composition and exposure. The tended young pure forests grown on the sunward slopes are most seriously damaged and non-tended middle-age mixing stands grown on the sunless slopes are most lightly damaged. Therefore, in order to preventD. superans from seriously damaging larch forests, relatively large crown density (P > 0. 7) should be kept, and broadleaf trees should be also properly preserved.