Testing the effects of incorporating TOPMODEL into the SSiB4/TRIFFID model and simulation of the response of vegetation dynamics and surface water cycle to climate changes in a subalpine basin of southwestern China. Issue 8 (24th August 2021) - Deng, Huiping
Abstract: To investigate the response of vegetation dynamics and surface water budget to climate change on a basin scale, the biophysical/dynamic vegetation model SSiB4/TRIFFID was coupled with TOPMODEL (hereinafter referred to as SSiB4T/TRIFFID). The effects of the integration on hydrological simulations were examined and long‐term dynamic simulations of vegetation succession and the water–carbon balance were performed under different climate scenarios for a subalpine basin of southwestern China using SSiB4T/TRIFFID. The coupled model SSiB4T/TRIFFID produces higher soil wetness and evapotranspiration, lower total run‐off and more realistic partitioning of discharges between surface run‐off and base flow. All long‐term simulations for the subalpine basin show that the fraction of vegetation changes from a dominance of C3 grasses to tundra shrubs and then to forests. Annual evapotranspiration in the control run is 388.5 mm year −1 (dominance of C3 grasses), 445.3 mm year −1 (dominance of tundra shrubs) and 388.1 mm year −1 (dominance of forests). Under an increase in temperature by 5°C and in precipitation by 40%, the evapotranspiration of forests is the highest among the three vegetation types. In the humid region, Forest evapotranspiration increases the most with increases in temperature, which results in the role of forests in increasing run‐off changing to having no significant effect on run‐off, and then to reducing run‐off. In regions with water limitation, forest evapotranspiration increases the most as precipitation increases. The effect of forests in reducing run‐off increases with increased precipitation. The spatial variation in the climate exerts an important impact on spatial changes in forest–run‐off relationships.