Soil Water Uptake by Amazonian Trees and Simulation of Impacts on Energy Fluxes and Soil Moisture Dynamics at the LBA Flux Towers

Abstract

Observational and modeling studies show that a deeper soil water uptake by tree roots is required for evapotranspiration in the Amazon Basin. Therefore, this study performed three numerical modeling experiments with different depths of soil water uptake by Amazonian tree roots using the Eta/CPTEC regional climate model. In the “Control” and “Deep Soil Shallow Root” experiments the depth of soil water uptake by tree roots is set up with 2 m, while in the “Deep Soil Deep Root” experiment this depth is set up with 7.2 m, according to the observational studies. The energy balance at the LBA flux towers is better simulated in the “Deep Soil Deep Root” experiment than in other experiments. Moreover, with the “Deep Soil Deep Root” experiment the seasonality of evapotranspiration is reduced in the regions where there is strong seasonality of precipitation, while the seasonality of moisture is reduced in shallow soil layers and increases in the deeper soil layers. In addition, in the regions with strong seasonality of precipitation the deeper soil layers have an inter-annual hydrological memory, and in all regions the soil moisture memory is inversely related to the amount of precipitation, with different behaviors in each soil layer. In conclusion, the deeper soil water uptake by the Amazonian trees is important for the energy balance and soil moisture dynamics in the Amazon Basin.