Research On Forest Restoration Patterns Of Yangtze River Basin Based On Land Ecological Suitability Evaluation

Along with the impact of human activity and global climate change on the ecological environment of the river basin has been exacerbated, the environmental protection and ecological restoration of the Yangtze River Basin has become one of the important issues currently facing, as it is one of China’s important economic regions active. According to the land use, vegetation landscape pattern, natural environmental features, the indicators system of ecological suitability evaluation of the Yangtze River basin for forest restoration was established, combined with the national function zoning ecology and the Yangtze River shelterbelt construction goal, the establishment of vegetation. To reduce the influence of subjective evaluation process, the matter-element model of land ecological suitability evaluation was established to evaluate the land for forest restoration. The results as follows shows the amount, quality, limiting factors and its distribution of the land resources of the suitable land for vegetation restoration in the basin, according to which the potential restoration pattern of forest in the Yangtze River Basin is put forward:i)The Yangtze River Basin was divided into two evaluation area ——the upstream and the mid-downstream, and topography(elevation, slope, aspect), weather conditions(not less than 10℃ accumulated temperature, annual precipitation) and land features(land cover types, soil reference depth, soil texture, soil total nitrogen content) were selected as the evaluating indicators to establish indicators system of ecological suitability evaluation of the Yangtze River basin for forest restoration, while the relative significance values contributing to the suitability of land for forest restoration of the two evaluation areas were calculated by AHP. Index weights of Upstream and mid-downstream of the Yangtze River Basin are significantly different, the index weights of upstream : elevation> not less than 10℃ accumulated temperature, the average annual rainfall> slope> Soil Texture> aspect> soil depth> land cover type> total N, while the impacts of altitude, not less than10℃ accumulated temperature, the average annual rainfall, and slope are more pronounced; the index weights of mid-downstream : slope> soil Texture> soil depth> aspect> total N> land cover, elevation> not less than 10℃ accumulated temperature, the average annual rainfall, while the impacts of slope and soil depth are relative more prominence.ii) Evaluate the land ecological suitability of the Yangtze River basin by the land ecological suitability matter-element model. After the suitability evaluation of the land more than 15 ° sloping and bare land, the percentage of area of each of the three suitability classes, including highly, marginally and not suitable accounted for 88.81%, 3.01% and 8.18% of the total area of upstream, respectively. While the highly suitable are in the region altitude below 2000 meters; the marginally suitable are in the mountain region altitude between 2000 to 4000 meters; and the not suitable land Resources are mainly distributed in the altitude above of 4000 meters in the Qinghai Tibet Plateau, Yunnan-Guizhou Plateau and Hengduan Mountain region.iii) The percentage of area of each of the three suitability classes, including highly, marginally and not suitable accounted for97.81%, 1.71% and 0.49% of the total area of mid-downstream, respectively. As for the lower altitude and the good hydrothermal conditions, the main factors that affect the land suitability for forest restoration are slope, land cover types, soil reference depth and soil texture.iv) According to the results of land suitability evaluation, there are 54103km2 land resources belongs to the highly suitable areas which are suggested to be restorated as different types of forest according to local soil and climate characteristics, while the 2945km2 marginally suitable areas are suggested to be restorated as forest after improvement measures or the mixed forest grass vegetation transition for the regions has a certain degree of restriction in elevation, slope, soil depth and soil texture, etc.; and the 2436km2 not suitable areas restricted to the unsuitable altitude, climate, or the soil environment and its accumulation effect are suggested to be restorated as grass land.v) The ecosystem services of the Yangtze River Basin has improved 77.03397 billion yuan pre year after the forest restoration from 22.31837 billion yuan pre year to 23.08871 billion yuan pre year, evaluated by the Value Equivalent Method of Xie, while the forest ecosystem services which increased 110.297 billion yuan per year, and the grassland ecosystem services increase 1.584 billion yuan per year; at the same time the ecosystem services of farmland decreased by 34.746 billion per year and ecosystem services of desert decreased by 100 million yuan per year.