| Due to the fragile ecological environment of the agricultural pastoral ecotone in northern China,unreasonable human disturbance can easily cause a series of ecological problems,including reduced surface vegetation,soil erosion,desertification,and soil erosion.Reasonable protection and utilization can restore vegetation coverage and improve ecological conditions.Therefore,the regular changes in vegetation coverage have important warning effects on the ecosystem of the agricultural pastoral ecotone.The administrative region unit flag county plays a specific role in implementing the national land spatial planning.When refining and implementing the indicators issued by the superior national land spatial planning,it is first necessary to understand the resource advantages and ecological environment background conditions of the administrative jurisdiction.Especially for counties located in the agricultural and pastoral ecotone with fragile and unstable ecological environment as a whole,changes in surface vegetation coverage will directly lead to fluctuations in their ecological environment system during the development and utilization of land resources.Therefore,the systematic understanding of the changes in surface vegetation coverage caused by land use is not only an important basis for efficient utilization of land resources and maintaining a healthy cycle of the ecosystem,but also one of the important basis for formulating the national land development and ecological protection plan of the county.In this study,the Bairin Left Banner,located in the agricultural and pastoral ecotone of eastern Inner Mongolia,was used as the research area.Land use data and NDVI data from 2000,2005,2010,2015,and 2020were utilized.With the support of Arc GIS,geographic information map analysis,pixel dichotomy,and image interpolation were used to analyze the spatiotemporal composite change process of land use and the characteristics of vegetation coverage change in the study area.On the basis of overlaying the two,the study on the changes in vegetation coverage based on the spatiotemporal composite change process of land use was completed,and relevant countermeasures and suggestions were proposed.The main research findings of the study were as follows:(1)In 2020,the land use in the research area was mainly grassland,arable land,and woodland,with an area of 2570.16km~2,1900.99km~2,and1657.12km~2,respectively,accounting for 94.97%of the total area of the research area.In terms of spatial distribution,land use started from the central region and heading north,showing the characteristics of alternating distribution of arable land-grassland or arable land-woodland.Over the past 20 years,the main types of land use have been grassland,arable land,and woodland,with their total area accounting for over 90%of the total area.Woodland,grassland,and arable land constitute the matrix of land use in the study area,and the frequent conversion of arable land and grassland,as well as the transformation of grassland into arable land,are the main spatiotemporal composite changes in land use;In terms of spatial distribution,the arable land is centered around the Lindong Town of the Banner Government and extends southeast,southwest,and due west,becoming the main agricultural production area of the entire Banner.Grassland is mainly distributed in the central hilly areas,alternating with arable land,forming a utilization model of"This retreat and the other advance".The characteristics of agricultural and animal husbandry intertwined production are prominent.On the grassland ecological base,farmland utilization patches are embedded,and the overall grassland ecosystem forms a certain fragmentation phenomenon.The woodland is distributed in the northern mountainous areas.The process of land use change can be mainly summarized into five graph patterns,including stable and unchanging land use type,conversion between woodland and grassland type,conversion between grassland and farmland type,conversion between woodland and farmland type,and conversion between grassland,woodland and farmland type.Among them,the map of stable and unchanging land use type accounts for the largest proportion,accounting for 71.4%.The frequent conversion between woodland and grassland type is the second largest map type,accounting for 16.8%.The third largest map type is the stable and unchanging land use type,accounting for 11.52%.(2)From 2000 to 2020,the proportion of high vegetation coverage in the study area was over 50%except for 2010,which was 48.15%,and the vegetation coverage remained basically at a good level.The high vegetation coverage area is mainly distributed in the north,while the low vegetation coverage area is concentrated in the south,and the vegetation coverage shows a gradually decreasing trend from north to south,showing obvious regional differences.Over the past 20 years,vegetation coverage has shown an overall improvement trend in fluctuations,with improvement areas accounting for 54.3%of the total area,mainly distributed in urban areas in the central and southern regions,as well as various townships in the southern and northeastern regions;At the same time,there are 23.99%degraded areas,mainly distributed in the northwest and northeast regions.Therefore,the task is extremely challenging for protecting the ecological environment and making rational use of land resources.Among the two graph models that reflect the spatiotemporal coupling changes of vegetation coverage,the graph model with better vegetation coverage is the main one,accounting for58.82%.Among them,the area with consistently high and stable vegetation coverage is the largest,accounting for 35.13%of this type.It is concentrated in the northern part of the study area and extends around the Ulijimulun River;The proportion of map patterns with poor vegetation coverage is 41.18%.Among them,the area with consistently low and stable vegetation coverage is the largest,accounting for 36.47%,which is concentrated in the southern part of the study area.(3)In terms of the vegetation coverage change pattern under the spatiotemporal composite change mode of land use,the vegetation coverage is relatively poor under long-term arable land use or grassland use,while the overall level of vegetation coverage is better under long-term woodland use;Whether it is the conversion of woodland to grassland,grassland to woodland,or frequent conversion mode of woodland to grassland,the overall level of vegetation coverage is good,and the vegetation coverage was in high or middle grade,accounting for the majority.The land use conversion between grassland and arable land has adverse effects on the improvement of the overall level of vegetation cover.The land use model of returning farmland to forests in the agricultural pastoral ecotone has a beneficial impact on vegetation restoration and improvement of vegetation coverage level;Further exploration is needed to determine whether the conversion of land use patterns between forest,grassland,and arable land is beneficial for the restoration or improvement of vegetation coverage.(4)Based on the characteristics of vegetation coverage changes in the spatiotemporal composite change process of each land use,targeted protection measures were proposed for the problems and current situation of grasslands,arable land,and woodland. |
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