Suitability Evaluation On Consolidation For Cultivated Land In The Typical Black Soil Region Of Northeast China Based On The Method Of Ecological Niche-fitness Model With Variable Weight

With the accelerating process of urbanization and industrialization,the quantity and quality of cultivated land in the black soil region of Northeastern China have continuously decreased.Therefore,the protection for black soil is of very importance.Land consolidation is an essential implementation to protect cultivated land.The suitability evaluation is an important prerequisite and foundation for the implementation of cultivated land consolidation.At present,there are few reports on the suitability evaluation on cultivated land consolidation in this region.Therefore,Gongzhuling in Jilin Province was selected as a typical black soil region of Northeast China as the study area,with the introduction of the idea of dynamic weights.This study was carried on cultivated land consolidation in the study area with a modified weight niche-fitness model,by selecting 14 indicators from the four dimensions(natural conditions,infrastructure conditions,ecological sustainability and spatial stability).The Delphi and Analytic Hierarchy Process(AHP)methods were used to determine the basic weights of the indicators,then modifying basic weights through the method of variable weight.Based on judging the degree of closeness between the actual ecological niche and the optimal ecological niche of cultivated land consolidation,the evaluation models of the three types of indicators were determined.And the variable weight niche-fitness model for cultivated land consolidation in the study area was constructed.Afterwards,the suitability degree of cultivated land consolidation in the study area was divided into five levels by using a natural breaks tool in the ArcGIS software.At the same time,the optimal niche was taken as the standard of cultivated land consolidation,and the obstructive factors were determined quantitatively according to fre quency statistics.The key points and countermeasures for cultivated land consolidation were presented according to its different levels.The specific findings were as follows:(1)According to the ecological theory,this study obtained the ecological connotation of cultivated land consolidation by comparing the elements of cultivated land consolidation with the basic elements in the ecosystem.Meanwhile,the cultivated land consolidation system was analogized to an artificial ecosystem and identified as a life cycle and open organism.The cultivated land consolidation system was composed of cultivated land,artificial operation and its surrounding environment,which was an artificial process to exchange and deliver natural material conditions,infrastructure conditions,spatial stability and ecological sustainability,improving the amount,quality and efficiency of cultivated land and develop ecological sustainability.(2)The overall natural conditions of cultivated land in Gongzhuling City were suitable.The area of cultivated land for Grade III was the largest.The weights of indicators were modified by the variable weights to make the range of the niche fitness value of each evaluation index expand,showing the original range of weights from 0.54 to 0.80 was expanded to the range from 0.21 to 0.75.The accuracy of classification of cultivated land consolidation was improved,and the result of the dividing grades was more in line with the actual situation.The results of the divisions were as follows.The area of cultivated land for Grade I was 44840.56hm~2,accounting for 13.5%of the total cultivated land;the area of cultivated land for Grade II was 75443.67hm~2,accounting for 22.72%of the total cultivated land;the area of cultivated land for Grade III was 105913.23hm~2,accounting for 31.89%of the total cultivated land;the area of cultivated land for Grade?was 70388.66hm~2,accounting for 21.2%of the total cultivated land;the area of cultivated land for Grade V is35486.11hm~2,accounting for 10.69%of the total cultivated land;(3)It is suggested that the consolidation should be carried out according to the consolidation grades.The implement consolidation was recommended to give the priority to the northeast and the south-central regions in this study area.The Grade I areas of cultivated land consolidation in Gongzhuling City were mainly distributed in Yongfa Town,Chaoyangpo Town,and Nanweizi District.The main obstacles were farmland shelter belt ratio,distance from main traffic lines and irrigation capacity.The Grade II areas were mainly distributed in the towns of Huaide,Qinjiatun,Fanjiatun,and Taojiatun.The main obstacles were farmland shelter belt ratio,soil organic matter content and distance from main traffic lines.The Grade III areas were mainly distributed in the towns of Bolichengzi,Shiwu,Sangshutai,Daling,Xiangshui,Ershijiazi,and Yangdachengzi.The main obstacles were soil organic matter content,soil pH and field regularity degree.The Grade?areas of cultivated land consolidation were mainly distributed in the towns of Maochengzi,Shuangchengbao,Dayushu,Longshan and Liufangzi District.The main obstacles were soil texture,field slope and field contiguous degree;The Grade V cultivated land consolidation areas were mainly distributed in Shuanglong Town,Bawu Town and Heilinzi Town.The main obstacles were soil texture,irrigation condition and topsoil thickness.