Response of vegetation in the Thar Desert to monsoon rainfall: an investigation using NOAA AVHRR and meteorological data

The study of dependence of vigor and senescence of desert vegetation on monsoon rainfall is important in understanding the desert ecosystem. In the study reported here the response of vegetation in the Thar Desert to the monsoon rainfall is investigated using multitemporal NOAA AVHRR data of post-monsoon period and meteorological data of 1990 monsoon period for the nine core districts of western Rajasthan. The temporal profiles show three distinct characteristics and these have been interpreted in terms of cumulative soil-moisture budget during monsoon. The results show that the vigour and the senescence of desert vegetation are strongly correlated with the root zone cumulative soil moisture and somewhat weakly correlated with the cumulative soil moisture at the deeper layers. The plot of normalized difference vegetation index (a surrogate measure of vigour of vegetation) at the end of the monsoon vs. average annual rainfall shows the existence of three ecological zones.