Evaluation And Analysis Of Shelter Forest Quality In Hilly Region Of Central Sichuan

Located in the upper reaches of the Yangtze river,the hilly area in central sichuan is the most typical basin hilly area in China.Its soil and water loss is the most serious area in sichuan and even the upper reaches of the Yangtze river.The vegetation in the whole area is sparse,and its low ecological quality causes huge losses to industrial and agricultural production and people's life and property.Since 1960,the first phase of the Yangtze river shelterbelt project has been constructed in sichuan province,which has greatly improved the ecological quality of the hilly areas in central sichuan.However,due to the lack of scientific and reasonable management for a long time,the ecological and economic functions of the constructed changfang forest are low.Therefore,it is necessary to evaluate the shelterbelt scientifically and reasonably in the hilly area of central sichuan province,so as to provide a theoretical basis for the scientific management and management of the long-forested area.In this paper,5 research areas and 18 evaluation indexes were selected to carry out second-class forest resource survey and field survey,and 8 stand types were obtained.The principal component analysis(pca)was used to screen 18 evaluation indexes,and12 main indexes were finally determined.Then the principal component analysis(pca)and analytic hierarchy process(ahp)were used to determine index weights respectively.Finally,the indexes were graded according to the research status at home and abroad.The main research results and conclusions are as follows:1)establishment of index system: take the shelterbelt quality evaluation in hilly areas of central sichuan as the target layer(A);Biomass indicators,sustainability indicators and ecological factors indicators are used as criteria layer(B).Average DBH,forest age,soil thickness,altitude and other 12 evaluation indexes were used as index layer(C).2)evaluation results: among the 48 sample plots of shelterbelt in hilly areas of central sichuan,the good grade and general grade sample plots accounted for the vast majority;There are few high quality and poor shelterbelt plots.The proportion of natural(secondary)shelterbelts in high quality grade is larger than that of artificial shelterbelts.Community structure,soil erosion condition,hectare accumulation and litter thickness coverage are the main factors affecting forest quality.3)the study shows that the quality of shelterbelt in the hilly area of central sichuan is good,but there are few high-quality woodlands,so the quality of shelterbelt in the hilly area of central sichuan needs to be improved.Whether the community structure is rich or not is an important factor affecting the quality of shelterbelt.At present,the operating schemes studied are: zonal cutting,window widening and ecological thinning(different thinning intensity).Hectares of trees,tree crown density larger shelter forest,understory shrubs or herbs commonly relatively scarce,cause the community structure of a single,aiming at the situation of shelter forest,such as to open a window to fill it with pure forests rich management measures,needle mixed forests of ribbon cutting measures,according to the different areas of protection forest crown density using the suitable ecological thinning(different thinning intensity)management measures.