Abstract:
Warming-induced expansion in vegetation coverage and activity can accelerate the montane
hydrological regimes. However, the climate impacts on ecohydrology of forested valleys of the
Himalaya are uncertain. In this study, utilizing results of about three centuries of cellulose isotope
chronologies (δ
13C and δ
18O) of dominant tree species, geo-chronological proxies, bio-geophysical
dataset and simulations including satellite observations, we show an activation in the
ecophysiological processes including evapotranspiration (ET) since the 1950s. Observation
suggests rapid greening, while isotopic records indicate enhanced assimilation and transpiration in
deciduous species vis-`a-vis conifers post 1950s. Given strong vegetation-precipitation feedback and
superimposed on the increasing trends of conducive atmospheric factors affecting valley-scale
convective processes, intensification in forest ET is manifesting in a progressive enhancement in
extreme rainfall events (EREs) since the last few decades. Results suggest that representation of
ecophysiological processes and dynamics of seasonal moisture loading in observational and
modelling framework is critical for understanding EREs under climate change.
