| Optimizing rural spatial distribution is the foundation of China’s ecological civilization and Rural Revitalization Strategy.Its purpose is “the space for production is used intensively and efficiently,that the living space is livable and proper in size,and that the ecological space is unspoiled and beautiful”.The hilly area of Sichuan Province is an important part of the economic belt and ecological barrier of the Yangtze River,and it is also the region with the most vulnerable ecological environment and soil erosion in the upper and middle reaches of the Yangtze River.The problems such as the decline of the quantity and quality of production land,the disorder of living land and the destruction of ecological land are prominent.The spatial conflicts among the three functions of production,living and ecology are becoming more and more serious,and regional sustainable development and ecological security pattern face great challenges.Therefore,identifying and characterizing the characteristics of production–living–ecological land(PLEL)pattern,optimizing and adjusting the spatial distribution of PLEL have become an important path of Sichuan Rural Revitalization Strategy.However,the current land use classification system in China emphasizes the economic and social attributes of land,and does not consider the ecological function enough,which can not meet the needs of PLEL classification,identification and optimal allocation.Under the above background,this paper builds a three-level classification system of PLEL based on the identification of the main production–living–ecological function(PLEF).Taking215 typical towns in the hilly area of Sichuan Province as samples,the quantitative,spatial,and functional characteristics and impact factors of PLEL were studied.Secondly,based on the theory of ecosystem service value,this paper constructed the monetization evaluation system of the economic and ecological benefits of the land for the third generation,and used the fuzzy clustering method to identify and evaluate the optimal area of the comprehensive benefits of PLEL.Finally,based on BP-ANN and CLUE-S,the optimization model of quantity structure and spatial pattern had been established,which realizes the dynamic prediction of the optimal proportion of PLEL and the optimal allocation of spatial pattern.The main conclusions are as follows:(1)Based on the main function identification of PLEF,the classification system of PLEL has been established.This classification system reclassifies land use types into PLEL types;especially,ecological land was classified according to the national standards of Wetland Classification(GB/T 24708-2009)and the Classification and Codes for Forestry Resources–Forest Types(GB/T 14721-2010).The naming principle of PLEL was based on a natural ecosystem or land landscape patterns,which ensures that the PLEL types were easy to understand in concept and better to identify in space.The classification system of PLEL consists of a three-level classification.The first level class includes productive land(PL),living land(LL)and ecological land(EL),reflecting the main PLEF attributes of land use.The second level class includes nine types;the ecological land is divided into four types according to ecosystem types and related standards,the production land is divided into two types according to industrial attributes,and the living land is divided into three types according to social attributes.The third level class subdivides the second level class into 21 types.(2)Production land holds a dominant role in the hilly area of Sichuan Province,and production land(PL),living land(LL)and ecological land(EL)account for 66.06%,7.60%,and 26.34% of the area,respectively.The area of agricultural production land is the largest;forestland and rural living land rank second and third.The spatial patterns of PLEL in different regions of hilly area have differences.The proportion of PL gradually decreases from north to south,while the proportion of EL gradually increases from north to south,and the difference in LL is not obvious.The EL is mainly distributed in the upper and middle parts of hills,and the PL and LL are mainly distributed in the foot slopes and valleys.The main functions of PLEL in the hilly area of Sichuan are production and ecology.The production function is mainly for agricultural and forestry products,and the living function is mainly for cultural leisure and residential functions.There are little differences among the ecological sub-functions.There is a strong correlation between PLEL and natural–social–economic factors in the hilly area of Sichuan.Natural conditions such as latitude,relative height,and surface roughness have significant impacts on PL and EL.Social and economic factors such as population density,location and total industrial output value have a significant impact on LL.(3)In 2015,the average GDP of sample towns in the hilly area of Sichuan was 241500yuan/ha,with a per capita GDP of 49500 yuan,higher than the provincial average level,and the spatial distribution of northeast and south was higher than that of central and southwest.The average ecosystem service value(ESV)of sample towns were 42936.25 yuan/ha,and the average ESV per capita is 10401.21 yuan.The spatial distribution of south and southwest is higher than that of northeast and middle,and the lowest in the hilly area of Middle.Arbor forest land provided the highest contribution,which accounted for 41.25% of the total ESV,followed by riverine wetland,paddy field and arid land.Meanwhile,regulating services value accounts for 75.69% of the total ESV,mainly from regulation of water flows,regulation of water flows,air quality regulation and erosion prevention,followed by food and habitat services.The spatial distribution of ESV has regional difference,which generally increased from northeast to southwest.The total ESV accounted for 27% of GDP in Hilly area of research region,which was the input regions of ecosystem services.The imbalance between the supply and demand of ecosystem services was obvious in the typical Hilly area,especially in central regions.Cluster analysis was used to divide the study area into three types: benefit balance,benefit adjustment and benefit promotion.The benefit balance type towns were the best comprehensive benefit areas in the hilly area of Sichuan,and the optimal production–living–ecological land ratio is about 5:1:4.(4)In this paper,nine natural geographical and socio-economic indicators are taken as independent variables,and the proportion of production and ecological land is taken as dependent variables.The BP-ANN model for optimizing the quantitative structure of the three kinds of land is constructed,which solves the problem of fully reflecting the differences of regional conditions,dynamic and quantitative prediction of the optimal proportion of the three kinds of land.After BP-ANN optimization,the proportion of ecological land in sample towns increased by 9.2% on average,the proportion of production land decreased by 8.9% on average,and the proportion of living land was basically the same.At the same time,the optimization results of South and southwest hilly areas were close to the optimal structure of 5:1:4,and the proportion of ecological land in Central and Northeast increased significantly.Secondly,through the logistic regression of 10 natural economic driving factors,this paper analyzes the distribution probability of the suitability of the land type of PLEL,constructs the CLUE-S model of the optimization of the spatial pattern of PLEL,and study on the town of benefit promotion in the hilly area of central Sichuan.The CLUE-S model adopts the overall optimal strategy of the comprehensive benefits of PLEL.By transforming the production land in the areas with the lowest land production potential,large slope and complex terrain into ecological land,it improves the regional ecological service function while retaining high-quality cultivated land,improves the landscape pattern dominated by agricultural production land,and achieves the optimization goal of the spatial pattern of PLEL. |
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