The Benefit Evaluation Of Converting Farmland To Forest In Zigui

This paper is based on Forestry, Ecology and Economics theory, to systematically research the community characteristics, soil properties, hydrological properties, etc. of different tree species in Zigui's Converting Farmland to Forestry, with the methods of field investigation, visiting survey and data analysis, so as to reveal the local ecological environment and the characteristics of the evolution since then. This paper also evaluates the ecological benefits, economic benifits and social benefits of local Converting Farmland to Forestry, using the methods of macro-analysis, hierarchical analysis, questionnaire investigation, quantitative and qualitative analysis. Here come the conclusions.①Results showed that citrus trees mixed Amorpha fruitcosa forest exhibited highest soil bulk density, and the total soil porosity of Bamboo mixed Amorpha fruitcosa forest was higher than the other stands. Additionally, the non-capillary porosity was the highest in the stand with Bamboo. Comparing with farmland, the saturated soil water content and the non-capillary water-holding capacity increased by 42.5% and 221.4% respectively after returning farmland to forest. Moreover, the saturated soil water content was increasing significantly in stand with citrus trees mixed Amorpha fruitcosa, and the non-capillary water-holding capacity was greatest in stand with Bamboo. The average infiltration coefficient of Pinus massoniana Lamb forest was highest. The average of surface runoff in the mode of returning farmland to forest was decreasing with between 74.90 to 85.21% compared with hilly-gully farmland, and the coefficient of surface runoff was lowest in citrus trees mixed Amorpha fruitcosa forest. Comparing with farmland, the (?) soil erosion modulus of returning farmland to forest was decreasing 92.6%, and lowest in stab(?) with Bamboo. Additionally, organic matter increased averagely 50.19% in returning farmland to forest, especially higher in oaktree, Bamboo and Amorpha fruitcosa forest.(?) Converting Farmland to Forestry project has worked in Zigui, in this decade, water (?)ion has accumulated to 264831.2 thousand T, water purification has accumulated to 264831.2 thousand T, soil erosion has accumulated to 2180.7 thousand T, sediment deposition has reduced to 697.8 thousand T, lose of the soil organic matter has come to 35.4 thousand T, the lose of N has come to 8.4 thousand T, the lose of P has come to 10.8 thousand T, the lose of K has come to 93.4 thousand T, the amount of solid carbon has come to 1590.5 thousand T, among which the biomass carbon sequestration is 722 thousand T, and the soil carbon sequestration is 8676 thousand T, and the release of oxygen has come to 532 thousand T.③the total value of the ecological benefits has accumulated to 581325.1 thousand Yuan, in this decade, according to the willingness to pay for the Converting Farmland to Forestry project, including water and soil conservation benefit 186475.5 thousand yuan, soil improvement benefit 53610.5 thousand yuan, oxygen carbon sequestration benefit 94610.1 thousand yuan, the environmental cleanning benefit 60630.6 thousand yuan, the conservation of biological diversity benefit 185998.4 thousand yuan.④the obvious economic benefits of the Converting Farmland to Forestry project in Zigui. So far as to 2007, the county's economic benefit of direct currency cash has come to 267.5 million yuan. Meanwhile, the Converting Farmland to Forestry project has promoted local social restructuring, especially the rural industrial structure restructuring, has increased the farmers' income, has improved the quality of life of rural residents, and has promoted local development.⑤the comprehensive evaluation index system on Converting Farmland to Forestry project in Zigui. It contains three criteria, eleven sub-criteria, thirty-two indexs. According to the analysis of the survey data, this paper evaluates comprehensively Converting Farmland to Forestry project in Zigui, using the hierarchical analysis method, and gets the following results that ecological benefit plays the greatest impact as weighting 0.5481, then follows the economic benefit as weighting 0.2633, while the socila benefit has a minimum weight as 0.1886.