Changes in the Distribution Range of Alpine Desert and Its Responses to Climate Change in the Lenglongling Area of Eastern Qilian Mountains in Recent 30 Years
ZHANG Fuguang;ZENG Biao;YANG Taibao;College of Earth and Environmental Sciences,Lanzhou University;
we study on changes in the distribution range of alpine desert and its responses to climate change in the Lenglongling Range of Eastern Qilian Mountains in recent 30 years by using the distributed range of alpine desert in different years,which were obtained as threshold of NDVI and artificial visual interpretation,and were extracted form TM remote sensing digital images in the Lenglongling Area of Eastern Qilian Mountains from 1990 sto 2010 s.We analyzed the variation characteristics of the change of the distribution range of alpine desert,and then discussed the process and mechanism that the change of the distribution range of alpine desert responses to climate change.Meanwhile,we obtained the topographical data(altitude,slope,aspect)from DEM in the study area in order to discover the relationship between the change of the distribution range of alpine desert and topographical factors.The results indicated that alpine desert was shrinking gradually in the Lenglongling Range of Eastern Qilian Mountains in recent 30 years,but it was expanding in the local section;the shrinking area of alpine desert mainly distributed in the altitude of 3 700~4 100 meters and the expansion region scattered in the different altitude zones.This phenomenon has caused that the average elevation of the lower bound of alpine desert in the Lenglongling Range of Eastern Qilian Mountains nearly had significantly moved to higher altitudes,the move rate was about 23 m/decade during the study period.Under hydrothermal conditions control,the shrinking area of alpine desert in slope mainlyconcentrated in the range of below the gradient of 12,also due to frost weathering strengthen,debris slope and physical processes that affect,the expansion changes occurred in the low slope region.As the slope gradient increases,the change of the distribution range of alpine desert has decreased gradually.Meanwhile the shrinking and expansion changes of alpine desert have reflected in different aspects.The changes of alpine desert in sunny slope are greater than that in shady slope.The temperature in the Lenglongling Area of Eastern Qilian Mountains from 1990 to 2015 had a increasing trend and the increase range of temperature was significant,which showed as rapidly first and then slow and had warmed at a rate of about 0.3~0.5℃/decade.The precipitation had no obvious change,but fluctuated in the range of about 350~600 mm in time series.In this period,the climate change resulted in the change of the distribution range of the alpine desert,and the results showed that it was mainly controlled by the change of temperature.
【Fund】： 国家自然科学基金(40901056);; 中央高校基本科研业务费专项资金项目(lzujbky-2013-130);; 国家基础科学人才培训资助项目(J1210065);; 兰州大学地理学基地科研训练及科研能力提高项目
【CateGory Index】： P407;P461
【CateGory Index】： P407;P461