Studies seeking the understanding of the role played by the root systems in the recharge and drainage of forest soils, were developed in a sub-basin (Snake Catchment), in the Tijuca Forest National Park, Rio de Janeiro. Tensiometers were installed in areas with and without the presence of roots of arbore affixation. Along one year, daily readings were accomplished and, during the rains, in smaller intervals of time. It also took place the characterization of the vegetation structure, of the roots distribution biomass and analysis of the physical and hydraulic properties of the soil matrix.

The results demonstrate that the depths of 10 and 20 cm present the largest monthly medium suctions along of the year and the layer of 40 cm presents smaller suctions than the layer above it. The depths of 80 and 120 cm present the smallest suctions, with low variations along the monitorated time. During the rain events, the tensiometers around the trees present smaller suctions than the area without the presence of roots, which demonstrates a faster recharge in these areas. Shortly after the rainfall, the depth of 40 cm drains more rapidly. The most superficial layer wets and drains quickly, being this behavior related to the physical properties of the soil and the biomass of fine roots. In the subsurface layers, the recharge and drainage processes in the areas with presence of roots happen in a faster way, attesting the role played by the root systems as preferential infiltration pathways.