Research On Forest Health Evaluation Of Hunan Hupingshan National Nature Reserve

Forest is a complex biological community structure dominated by trees and other plants,which provides a material basis for human survival and development.The evaluation of its health not only involves the characteristics of forest community structure,but also includes site conditions,ecological functions,anti-risk ability and so on,which is highly comprehensive.In this study,based on the second-class survey data and field survey data of Hupingshan Nature Reserve,a forest health evaluation system with site conditions,forest structure,ecological function and anti-risk ability as the main body was constructed.The comprehensive evaluation method-entropy weight method was used to evaluate the forest health of Hupingshan Nature Reserve,and the spatial distribution characteristics of forest health quality were analyzed by spatial interpolation method.The main results are as follows:(1)Characteristics of sample plots.The altitude of 91 sample plots was 269～1840m,the slope was 7～42,the soil thickness was 25～120 cm,and the soil available nitrogen,phosphorus and potassium contents were 99.2～127.3,4.12～6.89 and 72.1～112.2 mg·kg-3,respectively,from the core area to the buffer area and then to the experimental area.The volume of trees in 91 plots was 18～125m3 ha-1,the canopy density was 0.18～0.82,and the coverage of irrigation and grass layers was 22%～48%.From the core area to the buffer area and then to the experimental area,the volume gradually increases,the canopy density gradually increases,and the coverage of irrigation and grass layers first increases and then decreases.Margalef index of 91 plots was 3.1～12.8,Shannon-Weiner index was 1.9～8.2,and soil effective water capacity was 268～1150 t ha-1.From the core area to the buffer area and then to the experimental area,Margalef,Shannon-Weiner index and soil effective water capacity gradually increase.The fire resistance of the core area is relatively high,and there is no significant difference in the resistance to pests and diseases among the three functional areas.(2)Comprehensive evaluation.An index system with site conditions,forest structure,ecological function and anti-risk ability as the criterion layer and 13 indexes such as altitude,stock volume,species richness and fire risk grade as the factor layer was constructed,and the weights of each index were determined by entropy weight method.The overall weights of the four criteria layers were 0.345,0.280,0.239 and 0.136,and the highest weight of altitude in a single index was 0.113.Among the 91 sample plots,the number of sample plots with "high quality" health grade was 5,accounting for 5.5%;The number of sample plots with health grade of "health" was 46,accounting for 50.5%;The number of sample plots with health grade of "sub-health" was 35,accounting for 38.5%;The number of sample plots with "unhealthy" health grade was 5,accounting for 5.5%;There is no "morbid" place.The corresponding forest area was:healthy(33391 ha)>sub-healthy(25784 ha)>unhealthy(3736 ha)>high quality(3657 ha).Kriging spatial interpolation method showed that from north to south,from the core area to the experimental area,the altitude gradually decreased and the forest health quality gradually increased.