The Study On Evaluation Of Land Ecological Security In Jingyang County Base On Land Use Changes

In order to maintain living and develop production,human beings develop and utilize land resources,which has changed the land cover and affected the structure and quality of land ecosystems.The evolution direction of land ecosystem structure and quality determines the quantity,quality change and spatial difference of land ecosystem services,and ultimately affects land ecological security.Jingyang County is located in the central part of Shaanxi Province.It has outstanding geographical advantages and natural advantages.In the context of the Xi-xian integration,The Jingyang County has gradually transformed from a traditional grain,cotton,vegetable and agricultural county to an industrial county,and its land use methods and structure have also undergone great changes.Sustainable development poses a huge threat.How to analyze the mutual trade-off and coordination between land use change and the ecological level of land,and use this to improve the ecological security of land in the county has become an important issue that Jingyang County needs to solve urgently under the background of "green" development concept.Based on the sustainable development theory,human-land relationship theory,and land ecology theory,this study lets the county area of Jingyang County as the research area,and analyzes the changes in the number of land uses,dynamic changes in land use,and landscape pattern changes.At the same time,a total of 78,723 100 m × 100 m grids constructed under GIS were used as the research unit,and the land ecological "structure-quality-service function" was used as the framework to select the land ecological security evaluation index system in Jingyang County.Then the analytic hierarchy process and CRITIC method were used to evaluate and analyze the land ecological security status of Jingyang County in 2018.Spatial autocorrelation was used to analyze the spatial distribution characteristics of land ecological security in Liyang County.Finally,some suggestions are put forward for the status of land use and land ecological security.Research shows:(1)Cultivated land and construction land are the main land use types in Jingyang County.Before and after the land use plan was revised,the land use change in Jingyang County was mainly manifested by a decrease of 4.02% in the area of cultivated land.The area of woodland increased by 2.24%.The proportion of construction land area increased by 3.97%.The grassland area is decreasing.The increase in water area was small and remained basically unchanged.Unused land showed a slight decrease.In the analysis of single land use dynamic degree,grassland dynamic degree is the highest,but it is negative growth.The rate of change of forest land and construction land is large and it is increasing.The change rate of cultivated land,water area and unused land is small.In the analysis of the land-use transfer matrix,the transfer of each type is obvious.The main transfer directions of cultivated land are forest land and construction land,followed by conversion to grassland and water.The main transfer direction of grassland is cultivated land and woodland.The amount of forest land self-transfer is small,and the relative holdings are relatively large.Almost all unused land flows out into cultivated land and construction land,and the intensive utilization rate of land use has been greatly improved.However,there is still a small part of cultivated land and construction land transferred to unused land.(2)The overall land use in Jingyang County is continuously increasing.From the perspective of townships,the higher land use and larger increase are located in the four townships of Gaozhuang,Yongle,Chongwen,and Jinggan in the southeast of Jingyang County.The land use of Taiping Town,Wangqiao Town,and Kouzhen Township experienced negative growth,mainly due to a decrease in cultivated land and an increase in the area of woodland,waters,and grasslands.The lowest level of land use is in Baiwang Town,located in the northwest corner of Jingyang County,indicating that there is less human activity.Forests and industrial and mining land coexist in the town area,and forests occupy most of the area.(3)In the landscape pattern index analysis,the Mean patch area index(MPS),Percentage of landscape types index(PLAND),and Largest patch index(LPI)of cultivated land are much larger than other landscape types.They are the dominant landscapes in Jingyang County.However,the total number of patches(NP),patch density(PD),edge density(ED),and landscape shape index(LSI)all increased significantly,reflecting the fragmentation of cultivated land.Woodland,grassland,water area,and unused land all showed different degrees of fragmentation on the patch type landscape index.In 2018,the overall landscape level of Jingyang County showed a trend of fragmentation.Although the county's overall landscape spread value is high,it is decreasing,indicating that there are more advantageous landscapes in the country,but the degree of spatial aggregation and connectivity is not optimistic.Both the Fragrance Diversity Index and Fragrance Uniformity Index increased,indicating that the landscape heterogeneity in the region is constantly increasing and the landscape dominance is decreasing.(4)The level of ecological security of land in Jingyang County shows obvious regional differences,and it is distributed in a “concave” shape as a whole,that is,the spatial pattern that is higher in the northwest and southeast and lower in the middle of the county.The area with the best land ecological condition is in the area of Baiwang Town in the northwest,and the highest value of ecological security appears in the Luanhe River Basin.The ecological security values of the four townships in Jinggan Town,Yongle Town,Gaozhuang Town,and Chongwen Township belong to the second echelon.These four townships are gathering places for construction land and have anomalies.The mix of unused land,cultivated land,grassland and other types of land in the county area alienates the internal structure of the land ecosystem,destroys the structure of the land,and causes spatial differences in ecological functions.The ecological security of land in Jingyang County showed obvious spatial agglomeration and correlation.According to the results of local spatial autocorrelation,the high-height(HH)clusters are mainly distributed along the banks of Jing River and at the foot of Cuo'e Mountains and Beizhong Mountains.They are mainly distributed in Baiwang Town,Kou Town,Jianglu Town,Zhongzhang Town,Taiping Town,Lagan Town,Gaozhuang Town,and Chongwen Township are the most widely distributed.The low-low(LL)agglomeration,high-low(HL)agglomeration,and low-high(LH)agglomeration have fewer distributions,indicating that the land ecological security of Jingyang County is relatively Aggregation of advantages.(5)Under the circumstance that the change in land usage have caused a number of land ecological problems,taking the potential problems of land usage in Jingyang into account,there are several measures could be taken in the future: a)improve the protection on the basic ecological barrier;b)enhance the regional control on land usage;c)assure the layout of ecological land;d)Allow for intensive use of land resources;e)reduce agricultural pollution;f)support the development of facility agriculture and other ecological agriculture;g)arise the awareness of ecological security protection and increase and h)increase the investment in eco-environment protection to optimize the land usage and ensure the sustainable utilization of the land resources.