| Land is the cradle of human survival and development,which provides a place for human life to survive and also provides the goods needed for human life.Therefore,the change of land is a non-negligible factor in the sustainable development of society and.economics.The research on the dynamic change of land use is related to the future human living environment,even the survival.The rationality and scientific nature of land use/cover change is the key to the sustainable development of human society.In recent years,people have paid too much attention to the type of land with great economic interests in land use for the sake of the pursuit of more economic interests,causing simplification of land use types and a decrease in the diversity of land,degradation of regional ecological security as well.Tongliao City is located in the east of the Inner Mongolia Autonomous Region.It is the largest hub of communication in the eastern and northeastern regions of Inner Mongolia Autonomous Region.It has been positioned as a sub-center city by the autonomous regional government.It is positioned as a provincial sub-center city by the autonomous region government and is an important hub city in the Bohai Economic Circle and the Northeast Economic Zone.Since 2000,due to the rapid development of population,economy,and urbanization,together with the deterioration of grassland and desertification,regional land use has changed rapidly,the population capacity of grassland environment in Tongliao has gradually decreased.Therefore,the accurate analysis of land-use changes and ecological safety assessment have important guiding roles in the conservation and sustainable development of land in the region.This paper based on remote sensing data of land use/cover change in Tongliao City in 2000,2005,and 2015.The land use/cover change trends and changes in Tongliao City are extracted and analyzed by using ArcgIS and ENVI,and the ecological security of Tongliao City was discussed,which provide reasonable countermeasures and suggestions for land use and ecological security in Tongliao City.The main conclusions of this paper are as follows:1.land use/cover change studies show:there was no obvious change in the structure of land use type in Tongliao City from 2000 to 2015,but the area of various types changed more obviously.The area of cultivated land and construction land has been increasing,and the area of forest land,grassland and water area has decreased,and the area of un-used land has fluctuations.It reflects that the policy of returning farmland to forest(grass)has little effect on the research area.(1)the present characteristics of land use:the main land use types of land use in Tongliao City are cultivated land and grassland,which account for 30.2%and 43%of the land area,respectively.The cultivated land is mainly concentrated in Kailu County,Tongliao City,Horqin Left Middle Banner,northeastern Horqin Left Back Banner,southwestern Hure Banner and Naiman Banner.The grassland is mainly concentrated in Jarud Banner,Huolin Gol City,northeastern Hure Banner and southwestern Horqin Left Back Banner.And the water resources in Tongliao City are extremely scarce.(2)the variation characteristics of land use:there is a continuous increase of the area of cultivated land in Tongliao City,and the area of grassland was continuously occupied by other types of land during the period 2000-2015.By 2015,the area of cultivated land in Tongliao City was 1,781,300hm~2,which accounted for 30.2%of the area of Tongliao City,with an average annual growth rate of 2.3%.In 2015,the area of grassland was 2,533,200hm~2,which accounted for 43%of the area of Tongliao City,with an average annual growth rate of-1.6%.During the period,the area of construction land in Tongliao City also increased linearly,from 131,000 hm~2in 2000 to 149,600 hm~2in 2015.The change in the area of forest land is small,its average annual growth rate is-0.31%,and the area is reduced by 2200hm~2during the period.The area of water decreases continuously,with an average annual growth rate of-6.88%,from126,600hm~2in 2000 to 113,600hm~2in 2015,a total reduction of 13,000hm~2.The un-used land decreases continuously during the period,from 850,000 hm~2to 847,200hm~2,with a total area reduction of 2800 hm~2,and the proportion of land area decreased by-0.05%.(3)Regional land use/cover regional differences:the northern terrain is stony hilly terrain,mainly mountainous grassland is not suitable for cultivation,suitable for grazing,so the land use is mainly animal husbandry,the southern region is buried hill,the loess hilly area,the use of cultivated land is mainly in the west of Naiman Banner and the south of Gulun Banner.The central part belongs to the West Liaohe River Basin,the terrain is sandy alluvial plain,the undulating sand dune and sand land distributes in the mountainous area,the transition zone between the hill and the alluvial plain,in Kailu County,Tongliao City,Horqin left flank,The area of cultivated land is larger than that of grassland.(4)Characteristics of land use/cover transfer:during the study period,cultivated land was converted into woodland and grassland in Tongliao City,mainly distributing in Zalutte Banner and Hollingol Cit;except for Tongliao City,the conversion of cultivated land to grassland was distributed in every county.The conversion of cultivated land to construction land is mainly distributed in Tongliao City and Horingol City,mainly because of the development of urbanization,resulting in the expansion of urban land,and the cultivated land conversion to unused land is mainly distributed in the Gulen Banner and Horqin Left-flank Banner.It is closely related to climate drought and environmental deterioration,and its transfer area and transfer area are 32100hm~2 and72800 hm~2.Grassland to cultivated land is mainly distributed in the middle flag of the left wing of Horqin,at the border of Kailu County and Zarutte Banner,the grassland to woodland is mainly distributed in the Zhaluti Banner,and the grassland converted into construction land is mainly distributed in Tongliao City and Hollingor City.The grassland is mainly distributed in Kulun Banner,Horqin Left-flanking Banner and Naiman Banner,and its transfer and transfer area are 90800 hm~2and 49500 hm~2.The water area converts to cultivated land is mainly distributed in the middle flag of Horqin left wing and the Naiman Banner.According to the analysis of the distribution of land use type conversion in Tongliao City,there are more conversion from other land use to construction land in Tongliao City and Horingol City.It shows that the expansion of the city occupies a lot of land;the middle flag of Horqin left wing is mainly water area and grassland into cultivated land,distribution is more concentrated,indicating that the area of cultivated land in this region is constantly expanding;the left wing flag of Horqin,Naiman Banner and Kulun Banner are mainly converted from other land use patterns to unused land,which indicates that land use is excessive in this area,resulting in serious land degradation and desertification.The water area is 14300 hm~2 and 1300 hm~2.2.The ecological footprint and ecological carrying capacity of Tongliao City show that the ecological footprint has already exceeded the ecological carrying capacity,thus the ecological footprint has been continuously strengthened.The contribution rate in the total ecological footprint is also the highest,indicating that the consumption of cultivated land and fossil energy resources is high.(1).The change of ecological footprint shows that the total ecological footprint of Tongliao City is rising continuously and the contribution of ecological footprint is as follows:fossil energy land>cultivated land>construction land.The other types of land footprint change is not obvious.(2).The study of ecological carrying capacity shows that the change of total ecological carrying capacity in Tongliao City is not obvious.It has been fluctuating between 2.685-2.735 from 2000 to 2015.(3).Single index evaluation of ecological security shows that the ecological footprint deficit and ecological pressure are continuously increasing,the ecological diversity decreases first and then increases,but overall the ecological diversity decreases.Since 2000,the area of cultivated land and construction land has been increasing.Land use types such as grassland,woodland and water area are occupied,which affect the coordination of land use.3.According to the comprehensive evaluation and analysis of ecological security,the land ecological security level is divided into four levels(security,basic security,relatively unsafe,very unsafe).The security level of Tongliao City has been declining and has evolved into a very unsafe level by 2007.By 2012,the degree of insecurity had been alleviated,but the security level was still in a very unsafe situation.The extent of land use in Tongliao City had already exceeded the carrying capacity of the land,mainly reflected in the drying up of lakes,the degradation of grassland and the intensification of desertification.In addition,the irrational development and utilization of grassland have a serious impact on land use diversity and ecological diversity,thus reducing ecological coordination.In order to make the land resources reasonable and sustainable use,the structure of land use should be adjusted and optimized further,the forest and grass should be returned to the steep slope cultivated land more than 25°.and the area of woodland and grassland should be enlarged.Strengthening the protection of water areas,strengthening the monitoring and management of surface and underground water resources,strictly protecting cultivated land,strengthening the construction of high standard basic farmland,improving agricultural infrastructure,and strictly controlling the scale of construction land,In particular,urban construction land should be economized and intensively utilized in order to prevent disorderly expansion,and the protection and construction of the ecological environment should be strengthened so as to gradually establish a virtuous cycle of ecosystems,so as to prevent the desertification of land and the scale of desertification from expanding.To promote the diversity and coordination of land use and provide ecological security for sustainable economic and social development. |
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