| Land consolidation in foreign countries has developed from solving the problems such as the contradiction between people and agricultural land,and the fragmentation of farmland to studying how to solve the problems of coordination between human settlement and ecological environment,reshaping the natural landscape,etc.,thus to realize the ecological land remediation and ultimately achieve the goal of harmonious coexistence of human and nature.In China,with the development of capital farmland construction,it has experienced three stages: "emphasis on quality-emphasis on quantity-emphasis on quantity,quality and ecological environment",and is currently in the stage of consolidation with the goal of "Nature and human are life community.".There is still a certain gap between domestic capital farmland construction and foreign land comprehensive consolidation projects.Therefore,the integration of landscape pattern evaluation and ecological network optimization in capital farmland construction is of great significance for improving the level of ecological construction in capital farmland areas.This study takes the agricultural transition zone-the core area of Chongqing(Jiangjin)modern agricultural park as the research area.The conversion of different land types,landscape element quality and landscape pattern changes in the two periods before and after remediation were analyzed.Ecological resistance were evaluated by using the minimum cumulative resistance model,and different ecological function zones were divided according to the evaluation results.Based on the cumulative cost model,potential corridors were extracted,combined with the principles of hydrological analysis to identify ecological nodes,and an ecological network system were constructed to provide support for improving the ecological level of capital farmland construction.The research results are as follows:(1)After the construction of capital farmland,the land use structure has undergone substantial adjustment.Abandoned land and cultivated land with larger slopes were adjusted to forest land and garden land.Residential land,transportation land,commercial land,water area and water conservancy facilities land have been increased.The transfer of different land types was mainly cultivated land,grassland,garden land and forest land,and the remaining land use types were converted to different degrees to each other.As the abandoned land and the larger slope of cultivated land are transferred to garden land and forest land,the garden land and forest land area increased significantly;Thanks to the construction of infrastructure such as roads,ditches and pits in the area,the area of water and water conservancy facilities and land for transportation increased.Forest land,residential land,transportation land,commercial land,water area and water conservancy facilities land,and garden land showed a positive dynamic degrees of the five land-use types,while the dynamic degree of grassland,cultivated land and other land were negative.(2)The evaluation of landscape elements showed that after the construction of capital farmland,the grade of comprehensive landscape quality remained unchanged,while the overall score was promoted to a certain extent,and the grade and score of ditch,road,and forest land elements were all improved.Except that the quality levels of the elements of residential areas and fields has not changed,the quality of other landscape elements has increased by 1 level.Before the consolidation,except for the residential element level was excellent,and the field block and forest land element levels were good,while the remaining elements levels were medium.Among the 13 indicators,except for the three indicators of road network density,the distance to road,and the distance to water source,which obtained 10 points,the tillage distance and Shannon diversity index obtained 8 points,the other indicators obtained 2-6 points.The score of ditch density and road accessibility were the lowest.After consolidation,except for the quality grades of the woodland and residential areas were excellent,the quality grades of the other elements were all good.Among the 13 indicators,except for the scores of 8 indicators such as field regularity,farming distance,irrigation and drainage guarantee rate,were not changed,the remaining indicators all showed different degrees of improvement.The ditch density score was increased by 4 points,and the average plot scale,plot fragmentation,road accessibility,and forest coverage were all increased by 2 points compared with before the consolidation.The results show that measures such as land leveling,optimization of roads and ditches networks,construction of ponds,and increased forest area can effectively improve the quality of landscape elements in the capital farmland construction area of hills and mountains.However,due to the limitation of hilly and mountainous terrain,13 evaluation indicators,5 landscape elements,and comprehensive landscape quality grades and comprehensive scores showed small change.(3)Both the patch level and the landscape level landscape indices were significantly improved.In terms of patch level,The NP,PLAND,AI,and ED of the cultivated field were the highest among all the landscape types.Cultivated land was the dominant landscape in the region,and its degree of fragmentation were improved.The NP,ED,PLAND and AI of woodland were the largest among the landscape types in the region.Ditch corridors and road corridors were interland distributed,presenting a landscape layout of “connected roads and connected ditches”.Which indicates that roads and ditches construction can not only improve the landscape connectivity between patches,but also significantly improve farming efficiency.In terms of landscape leve,except for the increase in SHDI and SHEI,the rest of the indicators decreased.The results show that the degree of landscape fragmentation and aggregation decreased,connectivity increased,heterogeneity weakened,landscape types tend to diversify,and patch shapes became more regular.(4)By analyzing ecological resistance,the study area can be divided into 4 ecological function areas,and 7 ecological corridors and 5 ecological nodes are extracted.Based on this,ecological network optimization measures were given.Through the analysis of landscape resistance,the area can be divided into four ecological function areas: ecological core area,ecological control area,ecological transition area,and ecological occupancy area.Combining the minimum cost model,hydrological analysis principle and ecological function zoning results,3 first-level corridors,4 second-level corridors,2 first-level ecological nodes and 3 second-level ecological nodes were extracted.Baded on comprehensive consideration of the current land use characteristics and other factors,the "one horizontal,five vertical,one belt,four sides,multiple points" layout and corresponding optimization measures were given.After the optimization of the ecological network,the degree of network closure,the average number of nodes and the connection rate of nodes were improved,which not only brings benefit to the landscape connectivity,but also the stability of the regional ecosystem. |
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