| Protection forest is one of the forest types in accordance with the business purpose, its business objective is windbreak and sand fixation, water and soil conservation, climate regulation, water conservation, reduce pollution and so. China began the construction of protection forest system in the nineteen seventies, in the process of construction and give full play to the improvement of the ecological environment and people’s production and living conditions of the role. However, in recent years the tree failure, protection forest has some management problems:reducing biodiversity, plant diseases and insect pests frequently, seriously restricting the sustainable development of protection forest system. protection forest system construction and management of the development imbalance phenomenon increasingly prominent, seriously affected the protection forest health, so how to evaluate the protection forest health has become one of the hot research fields of ecology and environmental science.Yangtze River Three Gorges Project, China ever building the largest water conservancy project, the Three Gorges reservoir area is submerged by the Three Gorges Project area, involving20counties, cities and districts. The Three Gorges hydropower station is located in the reservoir area is the largest hydropower station in the world. The Three Gorges hydropower station have a great role to provide power to central China, east China, southwest and other regions, promote the economic development of the western region, balance the difference between East and West. Because of the importance of the Three Gorges reservoir, reservoir protection forest plays an important role. The area of protection forest system construction in soil and water conservation, water conservation, building a complex stable ecological system, protecting the stability of ecology and environment in Three Gorges Reservoir Area as the target. Therefore, the research of protection forest health in the Three Gorges Reservoir Area has an important guiding significance for the ecological safety and protection forest sustainable management in the Three Gorges Reservoir area.Zigui County is located in the territory of the Three Gorges Dam project, shelter forest in forest type and composition has certain typical and representative in the Three Gorges Reservoir area. Therefore, based on the stand level, this paper takes Zigui County as the research object, establish protection forest health assessment index system including the stand structure, stand function, ecological environmental and health risks of4primary indexes,20secondary indexes. Through traditional ecology field investigation and related indoor analysis to obtain data, on the basis of relevant stand health assessment documents, this article formulate protection forest health assessment indexes scale, set the index weights by Delphi-AHP method, calculate the protection forest health index by the comprehensive index of ecological system health model, and analysis the Zigui County protection forest health. The main conclusions of this study are as follows:(1Construction of stand level protection forest health assessment indicator system. Through the summary of relevant forest health assessment documents, set up the stand level protection forest health evaluation index system, in quantitative indicators by using better good and poor to divide, formation of protection forest health assessment indexes rating scale, which provide the reference for the protection forest health evaluation of Three Gorges Reservoir area.(2)The overall quality of Zigui County forest health is not high. Protection forest health evaluation index system is established based on the stand level, the index weight is settled by using the Delphi-AHP method, and the protection forest health index is calculated by the comprehensive index of ecological system health model, so finally the change characteristics of Zigui County protection forest health is obtained:The composite index of Zigui County forest health in the range of0.5-0.9, mainly in0.65-0.75,66%of the total sample number; In an unhealthy state of the sample accounted for the total sample14%, sub-health state of the sample is61%, in a state of health of the sample is25%, in good health status of the sample is0.(3)Results analysis of Zigui County forest health. Zigui County has9kinds of protection forest type health order:broad-leaved mixed forest> coniferous and broad-leaved mixed forest>coniferous forest>broad-leaved forest>masson pine forest>cedar forest>other coniferous forest>economic forest>shrubbery, that is, the mixed forest> pure forest>economic forest> shrubbery.(4)Spatial variability of Zigui County protection forest health index. In the horizontal direction, the protection forest health index of12towns in Zigui County from south to north gradually decreasing trend; In the vertical direction, protection forest health index increased gradually with the increase of altitude, the altitude of more than1000m lower, so it is a certain vertical trend.(5)Analysis on the main factors influencing the Zigui County protection forest health. Through the Pearson correlation analysis between each index and Zigui County protection forest health index, stand origin, the number of seedlings, canopy density, species diversity, productivity, water conservation, soil conservation, carbon fixation and oxygen release, human disturbance9indicators and protective forest health index was significantly correlated, so the9indicators are became a major impact protection forest health factors in Zigui County.(6)Zigui County protection forest health regulatory proposals. Through the analysis of the factors affecting Zigui County protection forest health, the closing hillsides to facilitate afforestation, artificial supply of planting seedlings, build mixed forest, tending and thinning and strengthen the protection, prohibition of deforestation of5healthy control suggestions, in order to rapidly improve the protection forest health status in Zigui County. |
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