Effects Of Tending Thinning On Health Of Larix Principis-rupprechtii Plantation In Daqingshan,inner Mongolia

Forest health,as a forest management concept,has attracted wide attention from all walks of life.In this study,a total of 18 indexes including stand vitality,organizational structure,soil quality and stand resistance were selected from Shanggaotai Forest farm and Wudaogou Forest Farm in Inner Mongolia Nature Reserve to construct an evaluation index system.The comprehensive index method was used to analyze and evaluate the health status of Larix principis-rupprechtii plantation under different cutting intensification.To reveal the main factors of forest health,and put forward the corresponding health promotion measures.The main research results are as follows:(1)The healthy,sub healthy,and unhealthy plots of Larix principis-rupprechtii plantation account for 54.5%,18.2%,and 27.3% of the total plots,respectively,and are generally at a healthy level.The stand health status was different with the intensity of thinning.All the plots with the intensity of thinning higher than 35% of Larix principisrupprechtii plantation were in healthy state.The weak thinning and moderate thinning of Larix principis-rupprechtii plantation were mostly in sub-health state.The plots without thinning treatment were poor and all were in unhealthy state.The results showed that the forest health status was greatly improved with the increase of thinning intensity,and the best effect was achieved when the thinning intensity was 48.7%.(2)Using path analysis model,it was concluded that tree density and herb coverage were the main influencing factors of stand health status,while Margalef richness index,crown density,biomass and soil bulk density were indirect influencing factors.(3)According to the results of health evaluation and the judgment of limiting factors,with the goal of building a healthy and stable forest division with good ecological and economic benefits,the corresponding health improvement measures are proposed: To improve the effect of seed germination and regeneration,artificial promotion of natural regeneration should be strengthened;The container seedlings of Larix principis-rupprechtii were selected to be planted in the rainy season,and the tree species,age and spatial structure of the stand were adjusted appropriately to improve the sustainable recovery ability of the artificial forest,so that it could be gradually replaced into multi-layered forest of different ages;The introduction of native shrub seeds can improve the species diversity of understand vegetation,improve the diversity of forest trees and enhance the diversity of forest ecosystem;For stands with excessive density,appropriate nurturing measures should be taken,with Windows opened in the forest to expand gaps and promote the spread of herb and shrub seeds.