Research On Land Resource Characteristics And Protective Land Utilization Arrangement For Semi-arid And Sandy Land Area Based On Remote Sensing Technologies

The semi-arid and sandy land area is fragile to desertification in natural conditions.Furthermore,irrational land use intensifies land desertification.Taking Horqin Left Back Banner(HLBB)as a case study,using remote sensing technologies,the paper revealed the land use/cover pattern and characteristics of land use/cover change,based on land resource characteristics in semi-arid and sandy land area.And driving mechanisms of land use/cover change were explored.The stability of crop farming and its desertification risk were also studied.Vegetation growth status and soil moisture at different terrain were investigated.Land use arrangement in HLBB was proposed from macro and micro aspects based on the research results.The conclusions are as follows.(1)The semi-arid and sandy land area under continental monsoon climate,crop production can be guaranteed to some extent in wet year,partial wet year and normal year.This is the water resource basis underlying agro-pastoral ecotone formation and extensive cultivation with low crop yield.But,crop growth will suffer from serious water stress in partial dry year and dry year.Furthermore,the non-structural sandy land and windy weather in winter and spring in semi-arid and sandy land area make land easy to be desertification,in particular,the land with low vegetation coverage and bare land.(2)Land use/cover which was acquired from remote sensing images shows that the spatial variation of natural precipitation and land use determine the stability and spatial explicit differentiation of land use/cover pattern.From east to west,area weighted gravity center of cultivated land,area weighted gravity center of forest land and area weighted gravity center of grass land appear orderly.Grassland is the dominant type of land use/cover in HLBB.Soils with good water condition are given a priority for the agriculture and animal husbandry.This is accordance with the climate,terrain,agriculture and animal husbandry economy in HLBB.Cultivated land distributed at aeolian sandy soil is large,showing that land use is irrational at a degree and has the desertification risk in HLBB.The changes of land use/cover are dramatic.And changed cultivated land is mainly distributed at aeolian sandy soil and meadow soil.Changed cultivated land at aeolian sandy soil has desertification risk.(3)Under normal and rich precipitation conditions,dryland farming can have some grain production in semi-arid and sandy land area.Under this circumstance,HLBB became the agro-pastoral ecotone before the establishment of the Republic of China as a result of the evolution of human-land relationship and policies.From 1949 to 1970s,land was reclaimed largely under the condition of industry development slowly and the oriented grain production policy.Meanwhile,land desertification was severe.After the industrialization,socio-economic developed quickly,which laid a foundation for the conduction of ecological restoration projects.However,farmers increase cultivated land as far as possible at the circumstance of vast land resource,technology advances in agricultural production,and crop plantation and animal husbandry economy in semi-arid and sandy land area.And government reclaims land to increase cultivated land in semi-arid and sandy land area for the "Cultivated Land Balance Policy" in China.Thus,cultivated land area increases in general.(4)The study of maize growth status under different precipitation conditions during maize growth period with MODIS NDVI data indicates that precipitation variability of maize growth period is considerable and there is a big difference in maize growth under different precipitation conditions.This reflects the instability of crop farming in semi-arid and sandy land area.And this further illustrates the mode of extensive cultivation with low crop productivity;however,this land use type has the land desertification risk.(5)Vegetation growth status and soil moisture condition were studied with the method of land surface temperature calculated from remote sensing images.The results indicate that the micro terrain,namely alternating distributions of undulating sand dunes and marshy lands,results in the water redistribution law:with the increase of relative terrain elevation,soil moisture decreases gradually and maize growth becomes worse;while grass growth becomes worse in the beginning,but becomes better later.Therefore,land use types should be arranged in accordance with the micro topographic differentiation of soil moisture in the semi-arid and sandy land area.(6)Based on the findings above,macro land use arrangement is put forward according to water resource conditions,land use/cover pattern,and spatial differentiation of maize growth status:cultivated land use pattern in the east of HLBB and grass land use pattern in the west of HLBB.Micro land use arrangement is proposed according to the micro topographic differentiation of soil moisture.At the top of the terrain,the drought tolerant grass should be developed in order to fix sand dunes in achieving ecological restoration.At the low of the terrain,paddy can be developed;and drainage facility should be constructed if maize is planted.At the medium of the terrain,sustainably used cultivated land should be achieved by protective land utilization to avoid the frequent transformation of land use/cover.Only in this way,stable crop production and anti-desertification can be realized in this terrain region.At last,land use adjustment project is discussed based on protective land utilization idea.Land use adjustment project can be acquired by overlaying land use data,soil data,maize growth status data reflected by NDVI under different precipitation years,vegetation growth status data reflected by land surface temperature calculated from images.