Batista-Andrade, J.A., M.D. Daniels, and J.S. Hall. 2027. Earth-Science Reviews, early online access.
Abstract
Understanding the hydrologic cycle in the tropics is crucial for assessing the trade-offs associated with reforestation, water yield, and flood protection. While the forest ‘sponge’ effect suggests enhanced water infiltration and subsurface storage that may support groundwater storage and dry-season flow, the forest ‘pump’ hypothesis argues that reforestation reduces water supply via losses to vegetation demand and transpiration loss to the atmosphere.
Here, we synthesize studies from globally distributed tropical biomes that analyze reforestation and hydrologic processes. We found that available studies provide evidence for hydrological responses associated with the forest “sponge effect,” particularly increased soil infiltrability, reduced surface runoff and peak flows in reforestation studies in the tropics. However, evidence remains limited for several key hydrological components, including groundwater storage, dry-season flows, and catchment-scale water balances, restricting our ability to evaluate broader hydrological trade-offs associated with tropical reforestation.
Based on these findings, we synthesize conceptual models that summarize known hydrologic responses in reforested tropical regions. Overall, this review underscores key insights into the current understanding of the hydrological cycle with tropical forest cover recovery and identifies knowledge gaps critical to developing a unified model of hydrological response to tropical reforestation.
