Study On The Ecological Sensitivity Of Kashgar City Based On Land Use

In this paper,taking the Kashgar City as the research object,based on the basic frame of interrelation between ecological environment and land use, establishes the ecological sensitivity evaluation index system and grading standards under land use change with the methods of land use dynamic index, GIS spatial analysis function and analytic hierarchy process(AHP)in order to analyze the area ratio and change process of various land-use types such as farmland, garden plot, forestland, grassland, other agricultural land, residential and factory land, land for transportation, land for water facilities, unused land, etc. At the same time, this paper quantitatively studies the land use dynamic change, land type conversion, and the distribution, sensibility and change of ecological factors in Kashgar City for the past 40 years by analyzing the five most representative ecological sensitivity factors of slope, elevation, normalized differential vegetation index(NDVI),land-use type and water area in the research area. Finally, we have proposed some countermeasures about the protection and cons.In the respect of land use, the total area of Kashgar City remains stable, and the area sizes in 1990, 2000 and 2014 are all 55480hm2. The area decreased respectively by an annual average of-10.52hm2,-32.83hm2,-83.00hm2,-61.64hm2 and-6.26hm2. The area of garden plot, other agricultural land, residential and factory land, land for transportation has increased significantly respectively by an annual average of 72.72hm2, 8.76hm2, 111.84hm2 and 78.55hm2. The changes of various types of land use are different in different study phases. The dynamic degree of farmland, forestland, grassland, land for water facilities and unused land from 1990 to 2000 is larger than that from 2000 to 2014, and in the late study phase, the dynamic degree of other types of land use is all smaller than that in the early study phase.In the respect of land use conversion, during the period from 1990 to 2014, the farmland made up the largest percentage of the land converted to other types, and is one of the important sources of other types of land use. However, the area converted from other types of land use to garden plot is the smallest. The forest land was mainly converted from unused land; the grassland was mainly converted to farmland; other agricultural land, residential and factory land, land for transportation were mainly converted from farmland and unused land; the land for water facilities and unused land were mainly converted to residential and factory land followed by farmland, forestland and land for transportation. The types of land use with the largest converting area are residential and factory land, grassland, land for water facilities and unused land, whose area is 98.14hm2, 2.74hm2, 6.71hm2 and 32.80hm2 respectively, and accounts for 74.30%, 68.16%, 65.15% and 49.95% of the total converting area. The types of land use with the largest converted area are unused land, farmland, residential and factory land, land for transportation, whose area is 1.68hm2, 13.18hm2, 1.68hm2, 98.14hm2 and 24.01hm2 respectively and accounts for91.30%, 86.48%, 77.42%,69.57% and 90.30% of the total converted area. The conversion trend among farmland, forestland, residential and factory land, land for transportation, and unused land is significant.In the respect of ecological sensitivity, the distribution of ecological sensitivity of each factor is different. From the perspective of the distribution of sensibility, the highly ecological-sensitive area and moderately ecological-sensitive area are distributed mainly in the region with high vegetation coverage, low elevation and slope, large area of grassland. The sensitive area of slope is the largest, which accounts for 50.28% of the total research area; however, the low ecological-sensitive area and none ecological-sensitive area are distributed mainly in the hills, wasteland, unused land, etc. The sensitive area of water is the largest and that of slope is the smallest, which account for 76.33% and 2.97% of the total research area. the region with high slope has low sensitivity, and the region with small slope has high sensitivity. The region with high elevation has low sensitivity, and the region with low elevation has high sensitivity. The larger the area of water and vegetation is, the higher the ecological sensitivity is in this area. The sensitivity of land for water facilities, forestland, garden land, grassland, farmland and other agricultural land is high, however, the sensitivity of the residential and factory land, land for transportation, and unused land is relatively small. the high sensitive area is seriously influenced by humanity and has low restoring capacity. Due to its high sensitivity, it is essential to protect its ecological integrality and take it as an important ecological preservation area; the moderately sensitive area can also be influenced by humanity. This area has weak ecological functions, unstable ecological system, and a certain degree of restoring capacity, which shall be taken as a controlled development area; the ecological system in low and non-sensitive area is stable.