Tropical humid forests: water consumers or producers? The case of a forest fragment in the Atlantic Forest

Given the critical role of tropical forests in providing ecosystem services, extensive global efforts have been made to conserve and restore these vital areas. Despite the recognized environmental value of preserved forests, substantial uncertainties persist regarding the impact of reforestation activities on water recharge. While some studies suggest that reforestation might lead to a reduction in surface and groundwater reserves, other research, backed by public opinion, indicates that forest recovery enhances water reserve.

Recognizing this as a crucial scientific and environmental management concern, our study aims to explore the role of de and reforestation on soil hydraulic properties. Combining in situ monitoring of water status and soil physical properties, our study aimed at addressing the following scientific question: how does soil structure evolve with different revegetation stages?

We selected several plots along a hillslope transect in the oceanic forest (Sao, Paulo, Brasil), with different reforestation stages (40 y.o. forest vs deforested pasture).  Deep percolation measurements were conducted using sealed bottom lysimeters. A comparative analysis of soil conditions in contrasted study areas involved soil physical properties such as texture, permeability, and bulk density, along with assessing the seasonal variability of matric potential and soil moisture content.

Our findings reveal that soil infiltration capacity of pasture was lower than under a 40 yr-old forest. We also observed that soil macroporosity  was higher under the forest area than  under the pasture area, potentially influencing infiltration rates and favoring deep drainage in the forest compared to the pasture.