Vegetation Response To Climate Change And Its Spatial-temporal Differences In Qaidam From1982to2012

At present, global warming has become an indisputable fact, as an important constituent in the ecosystem, vegetation is sensitive to climate change. Qaidam basin is a ideal place to research the pattern of vegetation response to climate change due to its special geographic location, obviously climate change and many types of vegetation. This paper using the GIMMS-MODIS NDVI data and meteorological data analyzed the change of climate and vegetation in the Qaidam basin from1982to2012, discussed the Spatial-temporal differences of vegetation response to climate change.Using the MODIS data, TM data and DEM data discussed the spatial characteristics of NDVI change in study area since2000. The research content and conclusions are as follows:Using meteorological data anlysed changes of climate from1982-2012, the results show that: Precipitation in growing season presented growth rates of2.38mm/a in Qaidam, the eastern basin growth trend of precipitation is greater than the western, Precipitation in growing season in Mountain regions of every basin in Qaidam basin presented rising trends except gasikule lake basin and dulan lake basin, Precipitation in growing season in oasis regions of every basin in Qaidam basin presented rising trends except gasikule lake basin, dachaidan lake basin, taijinaier lake basin,sugan lake basin and dulan lake basin.Average temperature in growing season in Qaidam presented growth rates of0.067℃/a, the western basin growth trend of temperature is greater than the eastern, mountain and oasis regions of every basin in Qaidam basin all presented rising trends.Applying NDVI data anlysed changes of the NDVI average in growing season in Qaidam and Mountain and oasis regions of each basin in Qaidam basin, the results showed that:NDVI average in growing season in Qaidam presented growth rates of0.72%/10a. Mountain and oasis regions of each basin in Qaidam basin presented the different levels of significant growth trend from1982to2012.Combining NDVI data, meteorological data with correlational analysising method anlysed the relationship between NDVI average and climate in growing season, the results showed that: The relationship between NDVI average in growing season in Qaidam both Showed significant positive correlation, Correlation coefficient is0.54and0.36. The relationship between NDVI average in growing season and temperature&precipitation presented a three-part response law which1989and2002were used to be as turning point in the eastern Qaidam basin of dulan lake basin, dabuxun lake basin and tuosu lake basin.The relationship between NDVI average in growing season and temperature&precipitation presented a two-part response law which extreme events of dry year in1994and1995were used to be as turning point in the western Qaidam basin of gasikule lake basin, dachaidan lake basin, xiaochaidan lake basin, sugan lake basin and taijinaier lake basin.Using MODIS-NDVI data with higher-resolution anlysed spatial characteristics of vegetation change in Qaidam basin from2000to2012, the results showed that:Although the area of each variation trend accounted for different proportions of the total area in each basin,all basins presented that the area of greening area was the biggest, followed by stable area and degraded area. This state the growth status of Vegetation tends to improve in Qaidam basin.Then using MODIS-NDVI data and DEM data anlysed mountain NDVI average in growing season and NDVI annual growth rate in each altitude of each basin from2000to2012, the results showed that:With the increase of altitude,Mountain NDVI average in growing season and its growth rate showed a obvious synchronicity. The bigger the NDVI value is, the bigger linear growth rate.Employing MODIS-NDVI data and DEM data anlysed the area percent of every trend of mountain Growing-season NDVI averages in each altitude、slope、aspect of each basin from2000to2012, the results showed that:With the increase of altitude, the area percent of mountain greening area in different altitude of every basin all showed a trend of decrease after the first increase, the area percent of Mountain stable area in different altitude of every basin all showed a trend of increase after the first decrease as a whole, except tuosu lake basin showed a increase trend. Mountain greening area mainly distributed in gentle slope, With the increase of slope,the area percent of mountain stable area in different slope of every basin all showed a increase trend, except gasikule lake basin and taijinaier lake basin showed a trend of decrease after the first increase as a whole. Greening area in Mountain region of gasikule lake basin,dachaidan lake basin,xiaochaidan lake basin and sugan lake basin took up the Largest area in north aspect, greening area in Mountain region of taijinaier lake basin,dulan lake basin and tuosu lake basin took up the Largest area in south aspect, greening area in Mountain region of dabuxun lake basin took up the Largest area in west aspect. Stable area in Mountain region of dachaidan lake basin,xiaochaidan lake basin,sugan lake basin,dabuxun lake basin, dulan lake basin and tuosu lake basin took up the Largest area in east aspect, stable area in Mountain region of gasikule lake basin took up the Largest area in west aspect, stable area in Mountain region of taijinaier lake basin took up the Largest area in south aspect.Using TM data and Google earth image anlysed the spatial distribution characteristics of NDVI changes in oasis of each basin since2000, the results showed that:Degraded area in oasis of Qaidam basin mainly distributed in human-dominated area and the edge of the oasis, greening area in oasis region mainly distributed in farm area and the area Near river.Based on the above research, we got the following conclusion:1. Precipitation and temperature in growing season both presented growth trend in Qaidam, eastern basin growth trend of precipitation is greater than the western, while western basin growth trend of temperature is greater than the eastern from1982to2012.NDVI average in growing season in Qaidam also presented a growth trend at the same time.2. Under the background of different climate, The relationship between NDVI average in growing season and temperature&precipitation presented a three-part response law which1989and2002were used to be as turning point in the eastern Qaidam basin.The relationship between NDVI average in growing season and temperature&precipitation presented a two-part response law which extreme events of Dry year in1994and1995were used to be as turning point in the western Qaidam basin.3. The growth status of Vegetation tends to improve in Qaidam basin since2000. Terrain and human activities are the important local factors for Spatial-temporal differences of Vegetation response to climate change in mountain and oasis of research area.