| Land resources are the material basis for mankind’s survival and development.With the strength of the human activities and land resources utilization isincreasingly intensified, the destruction of the land ecological environment hasbecome increasingly serious, and the research of land ecological status has becomethe cutting-edge topics of the sustainable land use.Based on western ecological fragile areas Yuzhong County in Gansu Provinceas the research area, this paper analyzed the change of land use, topography,vegetation, landscape pattern and soil erosion by GIS, and reflected the landecological risk condition under the influence of single factor. On this basis, natural,economic and other factors that were closely related with land ecological situationwere chosen to construct the evaluation index system. At the same time, for thepreliminary discussion on the influence of different evaluation unit on the evaluationresults, we chose grid and administrative divisions as evaluation unit. According tothe data provided by the Yuzhong County,200m×200m grid and30m×30m gridwere suitable for grid evaluation. According to the final evaluation results, we foundthat the200m×200m grid can not only reflect the detailed evaluation informationensuring the accuracy of the evaluation results, at the same time was similar with theresult of30m×30m grid covering the information needed for evaluation. Finally,combining with the evaluation results and characteristics of land use of the studyarea this paper made the early warning of the land use status2020of YuzhongCounty and land ecological recovery and protection measures were discussed.Summary and conclusions of the research are as follows:(1) Land use has important implications for land ecologicalcondition. According to the land use data in1996and2010of Yuzhong County, thispaper analyzed Yuzhong County land use change from1996to2010.The main typesof land use of Yuzhong County are farmland and grassland, cultivated land accounts for38.38%of the total area2010, grassland accounts for41.13%of the total area.From the Analysis of land use changes in1996~2010of Yuzhong County, we canget that the biggest change of land use type between15years is the grass falling by15012hm2, cultivated land and construction land increased respectively7393hm2and4656hm2. Because of social development, economic interests and the increasein population of Yuzhong County, dependence on land is increasing; a lot of grass isadjusted for construction land and the cultivated land.(2) Topography and land ecological conditions are closely related. The lowestpoints of Yuzhong are Shanghuacha Town and Yuanzicha Town locating in the mostnorthern part of Yuzhong at an altitude of1429m. The most point is located thesouthern part near Mapo Town at an altitude of3677m. The whole groundmeteorological north is low, the central is relatively flat liking a saddle.The area in0°~5°slope is52680hm2accounting for16.00%of the total area.5°~10°areacovers an area of68408hm2, accounting for20.78%of the total area.10°~15°areacovers an area of82568hm2, accounting for25.08%. Area of5°~25°is95492hm2,29.31%of the total area. And the area of greater than25°is29068hm2,8.83%of thetotal area.(3) Vegetation coverage are mainly distributed in between20%~20%,accounting for52.2%in the study area. High vegetation coverages are mainlyconcentrated in woodland surroundings in southern mountain and vegetationcoverage of the lowest place is located in the extreme north of the Yuzhong County.As a whole, vegetation of Yuzhong present meteorological north low trend and thereason is that the south elevation is relatively high; the amount of cultivated land,forestland, shelter forest land and natural grassland which is pollution-free is higher,northern Ma Po, new camp in the most significant. Mapo and Xinying Town are inthe most significant.(4) According to the characteristics and spatial scales of the study area, thepaper analyzed land use maps of the20towns in2010of Yuzhong County usingFragstats3.3software and selected six landscape pattern indexes to analyze thelandscape pattern which is helpful for better understanding of the whole area of landscape ecological conditions.(5) The soil erosion area of Yuzhong County reaches830.295hm2accountingfor21%of the total land area which is one of the cities with severe soil and waterloss in loess plateau and belongs to the fifth sub-region of gullied loess plateau hillyarea.(6) The range of land ecological condition composite index in the study area is3.7462~3.7462and ecological condition is given priority to with good or generalcondition. The area statistics show that ideal area of44452hm2accounts for13.60%of the total area of the study area, in good condition area of82456hm2,25.23%ofthe total area, the general state of an area of108148hm2, accounting for33.09%, thepoor state of an area of55596hm2,17.01%of the total area, and the bad state of anarea of36144hm2, accounting for11.06%of the total area of the study area.(7) By simulating and warning we can find that construction land willincreased significantly until2020, especially in the central and western regions, theincrease is especially striking. New construction land mainly concentrates around thecurrent situation of construction land. This shows that land use type has a greatimpact on cellular transformation and other spatial variables by attaching to thepresent situation of land use types affect the expansion of construction land. |
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