| As the material basis of human survival, land is an extremely important resource. The total land area of our country is extensive, but at the same time, the population base is large, the quality of cultivated land is small, and the land degradation phenomenon is more and more serious, so how to rational allocate land use types, improve land use rate and output of land, become one of the current hot research under the background of vigorously promoting the regional land use sustainable development strategy. In recent years, Lancang has large-scale introduction of Eucalyptus, rubber, coffee and other artificial economic landscape, instead of the original arable land, secondary evergreen broad-leaved forest, Simao pine and other land use types, at the same time with the implementation of Nuozhadu hydropower construction project and airport project, the area of water, construction land, natural forest and garden land in Lancang county changed greatly, which affected the ecosystem environment and regional production value structure of Lancang County in a certain extent. Therefore, selecting Lancang County as the research object, from three aspects of the social, economic and ecological to optimize the land use structure, to provide reference for the formulation of land use planning and sustainable development strategy in Lancang county.This paper taking the seven aspects of construction land planning constraints, ecological environment constraints, other macro constraints and mathematical model constraints as constraints, and taking social, economic and ecological benefits as the quality structural optimization objectives, and taking land use suitability and spatial compactness as spatial structure optimization objectives, constructing GMDP-ACO optimization model to optimist the land structure in Lancang county. The main conclusions are as follows:(l)The land use types in Lancang county are mainly in woodland, cultivated land and garden land, urban construction land is less, and the forest coverage rate is over 63.1%, and the ecological environment is relatively good; The average output of land of Lancang county is lower than that of Yunnan province and the national level at the same period, the economic efficiency of land use is low; the patch density index of urban construction land and rural residential land is small with theinterference from human, the patch density index of grassland is also small,because of its samll area and the distribution position, and the patch density index of other land use types was larger; for each type of land, the fractal dimension index are less than 1.1, the geometrical shape is regular.(2)Taking the social benefit index, land economic benefit and ecosystem services value as the object, to construct grey-multi-objective dynamic programming model (GMDP) to optimist the quantity structure of Lancang County.In the result of land use quantity structure optimization in 2020, set three scenarios by the population growth speed of slow, moderate and fast. Results show:the three scenarios’economic benefit and ecological benefit are both higer than the General planning of land use in Lancang County(2010-2020) and the present situation of land use; the social benefit index is lower than the current situation, but the optimization program of scenario one and scenarios two are higher than the General planning of land use in Lancang County, and scenario three is slightly less than the General planning of land use in Lancang County. Under the three scenarios, the land use types of area change trend are farmland, woodland, rural residential land and natural reserves reduce, garden, urban construction land and other construction use land and waters increased, and grassland remained basically unchanged. In the comprehensive comparative analysis among the three scenarios of land use efficiency and the total population, select the scenario two as the best land use structure in 2020.The land use quantity structure optimization results of 2025 shows:after optimization, the economic and ecological benefits compared with the present situation of land use and the General planning of land use in Lancang County are significantly enhance; but the social benefits is below than those two, but the per capita possession of arable land is still more than the General planning of land use in Lancang County of the minimum value of 0.38ha/people, reaching 0.423ha/people, food security can be guaranteed; after optimization, the change trend of the area of various land use types is similar to the land use optimization results in 2020, when compared with the General planning of land use in Lancang County.(3)Taking the best land use suitability and the maximum space compactness as the goal, to format ant colony optimization algorithm (ACO) to ptimize the spatial structure of land use in Lancang County.The optimization results of 2020 showed that:at the aspect of Land use suitability, the average land use suitability of urban construction land is significantly higher than that of the present situation and the General planning of land use in Lancang County, and other types of land use is almost the same with the the present situation and the General planning of land use in Lancang County,the overall land use suitability level is become high. On the aspect of compact, the patch density index of land use types were obviously decreased after optimization, the fractal dimension index of cultivate land, forest land and rural residential land use types are almost keep the same, but urban construction land and natural reserve are increase. when compared with the the present situation and the General planning of land use in Lancang County, after optimization, the compact index of each land use type is increased, and the degree of land use fragmentation is obviously improved; On the aspect of Spatial transfer of land type, the transfer of farmland, garden and forest land and nature reserve land is large, compared to the General planning of land use in Lancang County, after optimization, more high-quality cultivated land and forest land resources will be protected.In the optimization results of 2025, compared to the present situation and the General planning of land use in Lancang County,the change trend of suitability, compact and space transfer is similar to the optimization results of 2020.(4)Taking GeoSOS as a platform, the optimization system of land use spatial structure in Lancang county is constructed. Screening of α、β、ρ parameter, the ACO optimization algorithm is constructed, the overall accuracy of the model validation is 94.07%, and the Kappa coefficient is 0.91. According to the comparative analysis results of the quantitative structure and spatial structure, which compared within the land use structure optimization in 2020 and the current situation and the General planning of land use in Lancang County, after optimization, the economic benefit and ecological benefit have improved significantly, the social benefit is stable, and the land use suitability and compactness is improved, taht means the GMDP-ACO land use structure optimization model is suitable for the optimization of land use in mountainous areas. |
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