RELATIONSHIP BETWEEN THE ECOLOGICAL FACTORS AND THE DAMAGE LEVEL OF PINUS MASSONIANA FOREST ATTACKED BY HEMIBERLESIA PITYSOPHILA

Damage level by Hemiberlesia pitysophila was classified based on the survival rate of needles of 2-year-old branches,shape of shoot and growing potential.Its accurate rate was up to 87.75% which was verified by current annual increment of stem analysis of 60 mean sample-trees.The comprehensive investigation of different subjects,which was done in 60 plots of 9 survey areas distributing over 6 counties and cities (Huidong,Shenzhen etc.),has revealed that light to medium damage to the forest floor most is the herb association group and Rhodomyrtus tomentosa association where the soil layer is deep,loose and rich,while relative serious to serious damage is Dicranopteris linearis association,Digitaria sanguinalis and D.linearis codom-inant association and in the top of the hill where the soil is poor and highly acidic.Among the factors of the stand,the relationship between canopy and damage level is represented by a polynomial second power equation and the lightest damage occurs in the forest of 0.5~0.65 canopy density.Water-vapour pressure also has a polynomial second power equation with canopy density and the lowest pressure value is obtained in the forest of 0.5~0.65 canopy density.Therefore,a resonable pruning,thinning and controlling canopy density between 0.5-0.65 may enhance the resistance of the forest against Hemiberlesia pitysophila.