Research On Land Use/land Cover Change On The Southern Slope Of The Qilian Mountains And Its Driving Force

As global environmental problems have become increasingly concerned,land use/land cover change is becoming a hotspot in the research of global change.And under the joint action of natural factors and human activities,land use/land cover change is undergoing profound changes.The Qilian Mountains is an important water conservation and protection area in China,and plays an important role in maintaining ecological security in western China.It is of great scientific significance to study land use/cover change in its driving force in the Qilian Mountains.Based on this background,this paper collected the remote sensing images of 1980,1990,2000,2010 and 2015 to analyze the temporal and spatial changes of land use/land cover and the dynamic changes of landscape patterns on the southern slope of the Qilian Mountains by using mathematical methods as well as models based on geographic information technology and remote sensing technology.The index system affecting the land use on the southern slope of the Qilian Mountains was constructed on the basis of natural and human factors aspects.Principal component analysis and regression analysis were used to study the driving forces of land use/land cover change.It is found that climate plays an important role in land use/cover change on the southern slope of Qilian Mountains,the meteorological data consisted of temperature,precipitation,sunshine hours and average wind speed in the Qilian Mountains from 1960 to 2015 were collected,and the temporal and spatial characteristics of climate were studied by using mathematical methods and ArcGIS spatial interpolation function.NDVI can reflect the coverage of vegetation on the surface.Glacier is one of the important land use/cover types in the study area.Therefore,two indicators,NDVI and glacier,are selected,Analyzed the changes of NDVI and glacier and its response to climate change.Results show that:?1?The land use type in the southern slope of the Qilian Mountains was mainly grassland,with the smallest area being construction land,accounting for 49.73%and0.36%in 2015,respectively.There were decreasing trends in grassland,forest land and water area,while cultivated land,construction land and unused land presented an increasing trend from 1960 to 2015.The transfer between land use types was dominated by the conversion between the water area and the unused land,where the water area was reduced by 165.37 km² and accordingly the unused land was increased by 154.22 km².The dynamic level of single land use for both the forest land and the cultivated land at Menyuan stallion farm was the highest,while that for the construction land at Muli Town was the largest.By analyzing of the driving forces of land use/land cover change,it is found that climate has a great influence on land use/cover change on the southern slope of Qilian Mountains.?2?Because the south slope of the Qilian Mountains sparse population,economic level is relatively backward and the low level of urbanization,the interference of human activities on the land use/cover changes as strongly in the central east area,the impact of climate change on land use/cover change greatly,selection,NDVI and glaciers index,this paper studies NDVI and glacier change and its response to climate change.?3?In the Qilian Mountains there was a fluctuating upward trend in temperature,with the rising rates of the average temperature from 1960 to 2015,the highest temperature and the lowest temperature,being 0.33?/10a,0.27?/10a,0.41?/10a,respectively.And the lowest temperature contributed most to the average temperature.The temperature raised with the increase of latitude and altitude.The annual average number of precipitation days and precipitation intensity both show a slow growth trend.The annual average sunshine hours and the average wind speed disclosed a downward trend overall,-2.68 h/a and-0.06 m·s^-1·?10a?^-1,respectively.An increasing trend in the rise rate of average temperature happened from southeast to northwest for years,whereas the precipitation gradually decreased from east to west.The pattern of annual average sunshine hours was low in the southeast and high in the northwest.The abrupt changes of temperature,precipitation and average wind speed were all concentrated in the 90's of the 20th century.The average temperature and precipitation in the eastern,middle and western part of the Mountain all had a period of about 6 years.?4?The changes of average temperature,precipitation on the southern slope of the Qilian Mountains synchronized with that of NDVI,showing a fluctuating upward trend.NDVI changes had clear responses to average temperature and precipitation.NDVI and The average temperature,precipitation in growing season all had a periodicity of 14 years.NDVI in growing season was slightly more sensitive to precipitation than to temperature.?5?From 1980 to 2000,the temperature rapidly increased in line with partially high temperature,less precipitation and rapidly melting glaciers.From 2000 to 2015,the temperature rose slowly,with low temperature,increased precipitation,and melting rate of glaciers slowing down.This referred to a significant response of glacier to temperature and precipitation.The change of glacier area was negatively correlated with the change of summer temperature.Taking year 2000 as division,increase in temperature before 2000?0.54?/10a?was much larger than those after2000?0.03?/10a?The area reduced by glaciers before 2000 was 6.17 times the decreasing area after 2000.This referred to a significant response of glacier to temperature.This study provides a reference for the government to develop and utilize the land resources reasonably on the southern slope of Qilian Mountains,and is of great significance to the ecological environment protection and sustainable development of Qilian Mountains.