Assessing the potential hydrological impacts of hydraulic redistribution in Amazonia using a numerical modeling approach

Most evidence for hydraulic redistribution is from ecosystems in relatively dry regions. Recent data indicate that hydraulic redistribution (HR) may also exist in the central Amazon forest. Assuming that HR can take place in all plant types in the Amazon region, this numerical modeling study examines how the hydrological impact of HR varies spatially and temporally. HR influences transpiration and total evapotranspiration the most in places and during seasons of intermediate soil wetness. Although HR increases the long-term mean of dry season transpiration, it can reduce transpiration toward the end of the dry season in extremely dry years when the HR-induced acceleration of moisture depletion leaves less water available later in the dry season. Deep roots may, however, mitigate some of this negative impact. This HR-induced reduction of water availability is contrary to the general notion of HR increasing plant water availability; the spatial and temporal variation of the HR impact documented in this study may help interpret field observational data and locate future field experiment sites to evaluate the HR hypothesis in the Amazon region.