Research On The Demarcation Of Basic Farmland On SuperLearner-LESA Model

Cultivated land is the material basis for human survival and social development.With the continuous expansion of urban construction land,the contradiction between urban development and cultivated land protection has become increasingly prominent.Basic farmland,as one of the important control lines in the territorial and spatial boundaries,is an effective measure for our country to implement strict farmland protection system.Under the background of the construction of national ecological civilization,the delimitation of basic farmland should take into account food supply,ecological support and the ability to restrict the disorderly expansion of cities.At present,the demarcation of basic farmland is mostly based on the research of cultivated land quality evaluation,agricultural land classification and model algorithm,but the research of demarcation of basic farmland based on model combination method is less.Therefore,based on the combination of SupreLearner and LESA models in the United States,taking Anhua County as an example,the basic farmland is delineated from the versatility of cultivated land:(1)Construct a LESA model.The LESA model includes two parts: land evaluation(LE)and site assessment(SA).The evaluation index system is established to calculate the score.The model is constructed by the development requirements of Anhua County.The LE and SA ratios of the model are set to 3:2.The results showed that most of the cultivated land in Anhua County had higher LE scores and lower SA scores.The comprehensive scores were mainly concentrated between 50 and 70 points.The overall quality was good,but the regional distribution was obvious.The area of cultivated land with high comprehensive scores is higher than that of the western region.(2)Demarcation of basic farmland based on SuperLearner-LESA.The number of basic farmland protection determined in land use planning of Anhua County was taken as the delimitation objective,and the LESA result is used as the model conversion rule to simulate the basic farmland.The results show that the basic farmland delineated is mainly distributed in Meicheng Town,Le’an Town and Qingtangpu Town in the southeastern part of Anhua County,along the Zijiang River area and Dafu Town and other ecological agriculture areas.There are fewer basic farmland in the west,and there are differences in regional distribution.However,the delimitation of basic farmland relies on the natural endowment of each township,mainly on the evaluation of cultivated land quality,and the evaluation of site conditions,and the overall quality of the basic farmland is better.(3)The simulation delineates the comparative analysis of basic farmland and actual basic farmland.The overlapping area of the two accounts for 72.30% of the basic farmland area defined by the simulation.Compared with the actual basic farmland,the basic farmland area is distributed in low-slope and low-altitude areas.The actual basic farmland is subject to policy,township development and major project implementation.If the impact is high,the cultivated land with excellent quality is not included in the basic farmland.The model reduces the influence of human factors.The quality of the cultivated land background is prioritized,and the model simulation results are more objective.The countermeasures and suggestions for delineating the basic farmland are formed.