The Health Assessment And Maintenance Machanism Of Pinus Armandii In The Middle Part Of Qinling Mountain

In this paper, Pinus armandii forest in the middle section of Qinling mountain was studied to make an assessment of its ecosystem health status and to make an analysis of the health impact factors, in order to explore the maintenance mechanism of the forest ecosystem, aiming at providing theory basis and technical support to the healthy management of the Piuns armandii forest in Qinling mountain area, fulling exploiting the forest ecosystem functions.(1) According to the different site conditions, 26 20m×20m sample plots in the Huoditang forest region in the middle section of the Qinling mountain were set to make an assessment of its ecosystem health on the basis of the ecosystem function, in which 4 primary factors and 22 secondary factors were studied, which are vitality(tree layer biomass, shrub layer biomass, herb layer biomass, community update, forest tree height, age, diameter at breast height, litter layer biomass), community structure(tree species richness, shrub species richness, herb species richness, stand density, canopy density, slop aspect), soil condition(water holding capacity, organic material, content of N, P and K, pH) and the resistance power(human factor, diseases and insect pests).(2) The results showed that the Piuns armandii forest in the middle section of Qinling mountain was between the age of 35~45 in general, which was in the transition from middle age stage to the mature stage. The forest had a low vitality in general, at average of tree height 11.73m, diameter at breast height 17.77cm, stand density 1233.6N/ hm~2, canopy density 0.573, tree layer biomass less than 40m~3, and tree update between 1000~2000N/hm2 which meant that the reserve resources were not enough.(3) According to the forest ecosystem health assessment model, samples data was analysed to get the weight and standard value. The results showed that 12 samples, accounting for 46.15% of all the samples, had the healthy ecosystem; and that 7 samples, accounting for 26.925% of all the samples, were in the sub-health state; and that none was in the unhealthy state. The average health index of the samples was 0.623, which showed that the Piuns armandii forest in the middle section of Qinling mountain was in the health state in general.(4) The analysis of correlation and field investigation showed that the canopy density, tree layer richness, slope aspect, human activities, diseases and insect pests were the factors which made a direct impact on the Piuns armandii forest ecosystem health. Therefore, closing hillsides to facilitate afforestation and forest thinning can be adopted to maintain the health of the the Piuns armandii forest in the middle section of Qinling mountain.