Application of NDVI on establishing the relationship between precipitation change and vegetation variation in central Taiwan

In recent years there was a decreasing trend in the number of rainy days but an increasing trend in rainfall intensity in Taiwan. The rainfall patterns in the so-called Mei-yu Season (often during May and June, it also called plum rain) have also changed, which is one of the significant evidences of short-term climate change. In this study, the NDVI (normalized differences vegetation index) derived from SPOT images was used to estimate the recent vegetation changes in central Taiwan, and examine the relationship between vegetation condition and precipitation. The results show that precipitation fluctuated considerably in the past 30 years and increased dramatically between 2003 and 2008. The mean NDVI change during Mei-yu season was negative between 1999 and 2008 but there was no significant inter-annual trend of NDVI in this period. NDIV did not significantly correlate to precipitation. Spatial variation of NDVI as indicated by the standard deviation differs in elevations and between windward and leeward slopes.