Characters Of Climate Change And Responses To Vegetation Index Of Qinling Mountains

Qinling Mountains are not only the important demarcation line of China’s North andSouth, but also the water south of the middle route of South-to North Water Divertion. Withthe global climate change status, we carried out field investigation based on GIMMS SPOTVEGETATION NDVI data during1983to2012. We research the climate characteristic ofNorth and South of Qinling Mountains and the relationship between vegetation and climatevariations. Subsequently, the studies of vegetation cover variation and its responses toregional climate change had been carried out. The main conclusions included:(1) The characters of humidity index variations of Qinling MountainsThe annual precipitation in south of Qinling Mountains are strongly larger than north.Coincidently, the annual precipitation between north and south are declined as same asdrought, but the south is more obviously. So, the differentiation among Qinling Mountains ismore and more small. Recently30years, the variation of seasonal precipitation show theprecipitation at summer and autumn is gradually more and the spring and winter is fewer andthe distribution of rainfall is zonal. The spatial distribution of the annual precipitation is southhither than north.(2)The characters of temperature variations of Qinling MountainsThe results show the temperature upward2.28℃in south and upward3.37℃,respectively. The temperature variations trend a seasonal characters, that is to say, the summeris higher and the winter is lower. Our data show changes in south hither than north. Southtemperature differs by less than3℃compared with0.77℃in summer. Temperature variationsat autumn is obvious than summer.(3)The spatial-temporal changes of vegetation and responses to environment changes ofQinling MountainsThe annual NDVI of the north and south region trends to fell only a little, but thespeed of fell in north is larger than south. The south Qinling Mountains belong to subtropicalclimate zone and covered by subtropical evergreen grass brush and broad-leaved forest, whichtemperature at autumn is higher. The NDVI index at autumn is larger than spring.Comparatively, NDVI index show alternate floating in north. The areas of NDVI are all positive values by calculating data at autumn and spring, which show increase. However,NDVI at winter and summer Show a downward trend.During1983to2000, there is a significant correlation (P<0.01) between NDVI indexand seasonal temperature in north regions at summer and spring. The correlation coefficient ofaverage NDVI index and annual average temperature is0.59(P<0.05).Consequently,temperature is one of the most factors. But, there do not show a significant correlation atspring, summer and autumn after2000. The reasons may be follows: global warming, thelower sensitivity between plants and temperature, human activities. But, there is closelyrelated between average NDVI index and temperature at winter, which correlation coefficientbetween the two is0.75(P<0.05), what illustrate the mainly change of NDVI index caused bytemperature. In north area of Qinling area generally is given priority to with temperatedeciduous broad-leaved forest. The more global temperatures rise, the more vegetationsensitive. That Can be used as a signal of regional ecological response. But this NDVI indexresponse to temperature is general back a month.