Study On The Comprehensive Benefits Evaluation Of Different Economic Forest By Returning Farmland To Forestry In Northwest Guangxi

The program of returning farmland to forestry is our country’s one of the major project of ecological environment construction. Since the policy of returning farmland to forestry introduction, all levels local governments have given a positive response, and the states have invested a lot of manpower, material resources and financial supporting. With the end of the first project of returning farmland to forestry, and the comprehensive benefit evaluation achievements of the project about returning farmland to forest, it has become a hot topic problems concerned by all levels of government and society, at the same time, it also is the object of all levels government departments and the project of undertaking department research and solve the practical problems.Taking three economic forests about the Walnut, Star anise and Chestnut by the project of returning farmland to forestry of Fengshan County and Donglan County project in northwest Guangxi as the research object, through analyzed and studied on the composition, conversion of the forest vegetation biomass, soil fertility, ecological benefit, social benefit and economic benefit. Through the analysis of field investigation and experiment showed that three kinds of economic forest conversion pattern of forest vegetation have a very good recovery, and the vegetation coverage increased significantly than before project. Soil structure was improved, soil bulk density, soil porosity, and the conversion has loosen, soil permeability and water permeability increased. Forest biomass increased, soil fertility and block permeability enhanced capacity of water storage, surface runoff on slope erosion is weakened, the modulus of soil erosion from1318.9t·km-2·a-1to790.1t·km-2·-1.It has ten years since returning farmland to forestry in the northwest of Guangxi; the forest coverage rate has3.5percentage points higher than that before project. Combined with the regional social and economic characteristics and background characteristics in Fengshan country and Donglan country during returning farmland to forest, and establish the comprehensive benefit evaluation index, and take the "substitute the project law" and "cost method" as the methods, analysis and calculation regional benefit value and comprehensive benefits of three kinds of economic forest patterns. By2012, Fengshan County and Donglan County have36600.8hm2about three economic forests. Fengshan County and Donglan County have total value of ecological benefits is54.4222million Yuan after modified and conversed, the value of protecting water resource accounting for the total value of ecological benefits is29%; the value of conserving soil resource accounting for the total value is11%; the value of purifying the environment accounting for the total value of ecological benefits is20%; the value of protecting biodiversity value accounting for the total value of ecological benefits is40%. After returning farmland to forestry, three kinds of economic forest models achieved economic and social benefits are remarkable, and promoted the rapid development of the local economy, and optimized the local industrial structure, and transferred the local labor force of rural surplus, and the fruit products of economic forests had increased the income of residents from farming, and indirectly promote the development of the secondary industry and tertiary industry.Through analysis and comparison on the recovery of forest vegetation, soil condition and the value of three kinds of economic forest, and consider Walnut and Chestnut are the ideal tree species after comparison to manage desertification in Northwest Guangxi, and they are a new phase of the conversion of cropland to forest project priorities.