Recent trends in changes of vegetation over East Asia coupled with temperature and rainfall variations

In this study, we investigated whether long-term normalized difference vegetation index (NDVI) data show climate change signals after the mid-1990s which are inferred from other studies on changing trends in precipitation and dust frequencies. In doing so, mean NDVI data for the growing seasons (April-October) from 1982 to 2006 were used for examining the spatiotemporal variations in the vegetation over East Asia, in conjunction with precipitation and temperature data. Results indicate that there was a prominent change in the trend of NDVI around the mid-1990s: a pronounced positive trend over most of the East Asian domain before the mid-1990s (1982-1996) and a reverse (or weakened) trend after the mid-1990s (1997-2006). The reverse trend is evident over the higher-latitude regions north of 50 degrees N and the eastern Mongolian border area. The EOF and SVD analysis suggest that the dominant warming trend until the mid-1990s led to the increased NDVI over the high-latitude regions. However, after the mid-1990s, the reverse NDVI trend found primarily in the east of Lake Baikal and the arid and semiarid regions south of 50 degrees N seems to be closely linked to local precipitation changes occurred abruptly in the mid-1990s. However, precipitation influences on the reverse NDVI changes are not clear over the high-latitude regions north of 50 degrees N.