The Ecological Suitability Evaluation For Agricultural Land In Xian Nangou Watershed Based On The Concept Of Carbon Production

Since returning farmland to forest was carried out,especially after the integration of CDM mechanisms and ideas, we don not know whether agricultural land in Xian Nangou watershed has the potential to carry out Clean Development Mechanism, which will affect the development and implemention of the agro-ecological economic sustainable development programs. Based on this, we must clear the ecological suitability of agricultural land in this area. For this purpose, we firstly classify the landbased on ecological suitability by the data of agricultural Land type through using vectorization, overlay analysis and spatial analysis based on GIS, then we clear the ecological suitability of agricultural land in this area through the measurement of potential value of carbon sink, which will help to the adjustment of farmland utilization structure and clear whether agricultural land in Xian Nangou watershed has the potential to carry out Clean Development Mechanism. The results are as following:1. In Xian Nangou, appropriate tillage/garden/forset/grass farmland is 175.37 hm2, 333.82 hm2, 3203.85 hm2, 829.17 hm2 respectivily, and appropriate tillage and garden farmland is 291.59 hm2. Compared with the existing land utilization condition, tillage, garden and grass farmland are suitable, but the distribution of the forest is not reasonable. For example, 32.28% of locust forest is located on the barely suitable areas, meanwhile, there are lots of appropriate forset farmland which are underused and exist in the form of weeds areas. Therefore, the utilization condition of forest and grass land in the areas should be adjusted, such as reducing the grass area, increasing locust forest area reasonably. Based on the concept of carbon production, the effect of carbon skin of forest is lower than that of grass, thus, the ecological suitability of agricultural land in the area could reach to the effect of lower carbon.2. In the way of farmland utilization in Xian Nangou watershed, the average net carbon sequestration ability of forset/grass/tillage/garden is 2.87 t/hm2、1.54 t/hm2、2.45 t/hm2 and 0.69 t/hm2, respectivily. Therefore, the results show that Net carbon sequestration ability of forset/grass/tillage/garden is forset > tillage > grass > garden. After the evaluation of the ecological suitability, forest area and ecological suitability has changed much, and now net carbon sequestration ability is 3.11t/hm2, which results to the increase of total amount of carbon sequestration in Xian Nangou. All the results show that total amount of carbon sequestration in the area are decided to the distribution and ecological suitability of the locust forest to a large extent.3. Currently, annual total amount of carbon sequestration of farmland is 9838.245 t in Xian Nangou. After the adjustment of farmland utilization structure based on the ecological suitability, annual total amount of carbon sequestration of farmland is 12806.09 t, which increases about 30.17%. Potential transaction value of carbon skin changes from 295147.35 yuan to 384183.48 yuan, which increases about 89036.13 yuan, 30.17%. Therefore, suitability of carbon production of agricultural land in Xian Nangou watershed is very good.