A Quantitative Evaluation Of Ecological Assets Based On Remote Sensing And LUCC In Ling-Yan Region

Lingwu City and Yanchi County in Ningxia Autonomous Region, is an environmentally vulnerable area. Sparse vegetation, soil and water losses and desertification create serious problems. Since the Grain to Green Program (GTGP) launched in2002in Ningxia, to some extent, eco-environmental quality is better than before. Evaluating the ecological assets based on remote sensing, and analyzing spatial-temporal dynamic change process, contributes to provide theoretical support for local environmental-friendly and sustainable development, and eco-environmental destruction and compensation policymaking.In this study, supported by3S techniques, we retrieved vegetation fraction and net primary productivity (NPP) based on RS, to estimate ecological assets in2001and2011in study area, combining with afforestation cost method, energy fixation substitution method, market valuation method etc. In the meanwhile, considering the impact of price fluctuation as time on comparative analysis, we utilized CPI in Ningxia to uniform value to the year of2001. Then, we analyzed spatial-temporal dynamic change of ecological assets, and the influence of land cover change on that, the results show that:(1) Between2001and2011, the ecological assets had a rise trend, were34.83×108yuan RMB and89.91×108yuan RMB respectively; the per unit area value were3427.44yuan RMB/hm2and8836.22yuan RMB/hm2, which also showed the environment in study area was going properly into better. The value of soil and water conservation and water conservation contributed maximum proportion for study area respectively; the minimum proportion of ecological assets was the value of nutrient cycling in2001and2011.(2) In spatial distribution, except paddy-field zone in Linwu City, the gross ecological assets of study area increased from northwest to southeast. The high-value region mainly distributed in paddy-field zone in Linwu City and Loess Hilly region in Yanchi County; while low-value region was mostly lied in the eastern zone of Linwu City. This distribution characteristic had a relationship with vegetation, soil and precipitation factors. (3) In terms of land cover types, the grassland made maximum contribution for gross ecological assets, followed by rainfed land. For per unit area value of ecological assets, the paddy-field owned greatest value with13466.06yuan RMB/hm2, then was irrigable farmland> woodland> rainfed land> build-up land> bush land> grassland> barren land> water. Each land cover change had a positive contribution for the change of ecological assets in study area, other land cover types apart from water made a negative contribution for the change of oxygen releasing value, water made a negative contribution for the change of carbon dioxide fixation value, while others all showed a positive contribution, and the variation contribution rate of the grassland was highest.(4) Among every towns and counties in two years, the gross ecological assets experienced an increasing tendency. Mahuang Mountain County, Dashuikeng Town, Hui’anpu Town and Huamachi Town all contributed more than10percent of gross ecological assets of study area, while the ecological assets of Dongta Town was lowest. The per unit area value in Wutong Tree and Mahuang Mountain County was highest, while Ningdong Town was lowest.