Spatial-temporal Changes Of NDVI And The Response To The Regional Climate In The Qinling-Daba Mountains For 25 Years

Aims to reveal the response of the regional vegetation changes to regional climate change, this paper studied the Spatial-temporal characteristics of vegetation cover variations in Qinling-Daba Mountains of shaanxi from 1982 to 2006 based on GIMMS / NDVI and SPOT / NDVI data sets by using the average vale method, differencing, correlation analysis and linear regression of one variable techniques. Main conclusions and progress are as follows:1. Vegetation cover of the Qinling-Daba Mountains trends to increase indistinctly as a whole during 1982 to 2003 with a linear regression trend of 0.0001. Increasing trends of NDVI were same in Northern and Southern Regions of the Qinling Mountains but lower than Daba Mountains. Especially the average spring NDVI indicates the most significant increase (P=0.038)with a linear regression trend of 0.0016.2. The pixel numbers of NDVI (?)0.3 vegetation had little variation, the middle and higher cover annual of 0.30.4 had more variation, the middle cover area had little decreasing trends and the high cover area had a steady increase trends,which showed that vegetation cover has improved in the Qinling-Daba Mountains for 22 years.3. Vegetation cover of the most areas trends to increase and accompanied by partial degradation or deterioration of vegetation in the Qinling-Daba Mountains for 22 years. Compared to the 20th century and the early 80s,the annual NDVI increased 1.63% than the 21st century in research area. The increased pixel(995) more the decreased pixel(727),which indicated the situation of vegetation cover in the 21st century improved than the 20th century and the early 80s.4. Annual NDVI variation have little positive correlation with annual temperature (P=0.13)and have little negative correlation with annual precipitation(P=0.367),but both did not reach significant levels .NDVI is correlated positively with temperature to greater degree with smaller correlation to precipitation, so the degree which vegetation sensitive to temperature is higher than that to precipitation. NDVI increased in the Qinling-Daba Mountains was an important signal of response to global warming.5.There exists lag between average season NDVI and temperature. Season temperature was the main driver for season NDVI variations. There were significant correlations between summer temperature and spring NDVI(P=0.02),autumn temperature and spring NDVI(P=0.035),spring temperature and summer NDVI (P=0.079) , autumn temperature and winter NDVI(P=0.035).6. The research showed that the annual NDVI had no significant positive correlation with the annual average temperature in southern part of Qinling Mountains(P=0.23), but the NDVI in spring and autumn had significant positive correlation with the corresponding temperature; the annual NDVI had a significant positive correlation with the annual average temperature in northern part of Qinling Mountains(P=0.0446), it is indicated that the northern of the Qinling Mountains are the sensitive areas of global warming , it was an important signal for the northern vegetation of Qinling response to global warming...