Ecological Benefit Evaluation Of Grassland Desertification Control Project

In order to prevent the trend of grassland desertification, a series of projects had been done. The construction of project increases vegetation cover, prevents desertification, and improves grassland environment. But the development and benefit of projects are unclear. Because ecological benefit is the immediate and remarkable, it is imperative and essential to establish a suit of ecological evaluation index system of grassland desertification control project.This dissertation introduces the"Vegetation-Blown Sand Activities-Soil"index system. Vegetation cover, biomass on the ground, grass height, plant diversity, annual plant ratio, fixed-sandy ratio, fixed-sandy fragmentation, flowing-sandy ratio, flowing-sandy fragmentation, wind erosion module, soil organic matter, soil mechanical composition and soil crust, are chosen as the components of this system. AHP, RS, GIS and Landscape are also used to evaluate ecological benefit of grassland desertification control project. The weight from evaluation index system can find that the weight of vegetation is first in rule layer, show vegetation is essential of ecological benefit of project, also is important compose, next is blown sand activities. The weight of vegetation cover, biomass on the ground and fixed-sandy ratio is bigger than other weight in index layer. They are important index to influence evaluation of ecological benefit of grassland desertification control project. It is correction with the purpose and background of grassland desertification control project,the analysis result is consistent with China's actual conditions, which proved evaluation index system was accurate,credible and applied.So, this evaluation index system of ecological benefit of grassland desertification control project can reflect the effect of the project objectively.Through analysis and comparison of each ecological benefit index of three projects (2001 aerial-seeding forest project, 2004 aerial-seeding forest project and 2004 sand closing and afforesting project), the result shows vegetation cover, biomass on the ground, vegetation height and so on vegetation index of inside project higher than outside project. At the same time of vegetation restoration, blown sand activities is controlled by projects. Compares with the before of project construction, fixed-sandy ratio, flowing-sandy fragmentation are increase and flowing-sandy ratio, fixed-sandy fragmentation are decrease. Patch number of fixed-sandy decrease and a lot of small patch link to big patch. This explains that large-scale patch of flowing-sandy landscape type divides by other landscape factor type (mainly semi-fixed and fixed sandy landscape type), the number of patch is increase and the area of patch is decrease rapidly. While making vegetation cover, biomass on the ground, vegetation height increase, projects lead soil physical and chemical properties improvement, such as soil organic matter and proportion of silver sand increase, soil crust appearance. The result of comprehensive evaluation of ecological benefit of each projects, shows that ecological benefit of 2001 aerial-seeding forest project is very remarkable, ecological benefit of 2004 aerial-seeding forest project and 2004 sand closing and afforesting project is relatively remarkable.