The relationship between central Indian terrestrial vegetation and monsoon rainfall distributions in different hydroclimatic extreme years using time-series satellite data

Abstract

The study explored the dependence of the Spatio-temporal pattern of rainfall and its variability on the spatial distribution of forests in Central Indian Landscape, which covers ~1Million Km 2 , includes five states, and supports a population of 329 million people. The monsoon rainfall is, thus, a crucial source of freshwater for these population. We analyzed the relationship between rainfall and satellite-derived vegetation vigour, vegetation fraction, and elevation across 22 experimental zones across central India (i.e., forested, non-forested, and agricultural regions; buffer zones within and outside forests). Around 87% of annual rainfall is received during monsoon, with maximum rainfall (~1600 mm) in Odisha and minimum (~900 mm) in Maharashtra. The average rainfall was greater (~1500 mm) inside forests than in non-forested regions (~1000 mm). Moreover, 245 mm km -2 yr -1 of rainfall observed over forests during monsoon, but only 215 mm km -2 yr -1 in non-forested areas. Overall, rainfall increases from forest edge towards forest core logarithmically at a rate of ~10 mm km -1 yr -1 , and it decreases exponentially when moving away from forest edge at an average rate of -20 mm km -1 yr -1 over 0-to-50 km range, and at a rate of -7.5 mm km -1 yr -1 over 50-to-100 km range. This rate of decrease was maximum in Madhya Pradesh and Jharkhand and minimum in Chhattisgarh. The results confirmed a crucial role of forests in the distribution of monsoon rainfall, but in the elevated and Western-Ghats regions orographic effect is dominant.These findings are of great concern to forest policymakers to conserve and protect the central Indian forests.