The ecohydrological interaction of snow and vegetation type along a climate gradient in the Alps

A mechanistic ecohydrological model, Tethys-Chloris, is used to elucidate patterns of carbon and water fluxes across gradients of microclimates and PFTs (grass, deciduous and evergreen trees) typical of an Alpine system. The ecohydrological model is validated to reproduce snowpack dynamics for forested and open sites worldwide using the Snowmip-2 dataset. The model has also been confirmed to reproduce vegetation productivity and energy fluxes for several locations in an Alpine climate or similar conditions (Fluxnet dataset). Two synthetic climate gradients are used. One is representative of a dry alpine internal valley and the other one of a wet exposed mountain side. Synthetic climate gradients are constructed to represent variability of conditions with elevation using ground observations of the Meteo-Swiss network and an hourly weather generator, AWE-GEN. Specifically, observed data permit the parameterization of the weather generator and the simulation of co-variation among the principal climate drivers, i.e., precipitation, air temperature, relative humidity, wind speed, solar radiation, and atmospheric pressure for elevation bands from 500 up to 3500 m a.s.l. Forced with different climate conditions, the three PFTs are allowed to evolve across the elevation gradient and for dry and wet conditions. The sensitivity of hydrological and carbon fluxes to the gradients of climate and vegetation types are addressed by simulating 30 years of ecohydrological dynamics. The representation of within canopy wind profile has been found of paramount importance in providing reliable results of vegetation-snow interaction. The approach allows one to infer complexities and characteristic signatures of PFTs on dynamics emerging from the interaction of climate, snow, and vegetation properties.