Bibliogr.

Piping erosion is a hidden subsurface process driven by concentrated underground flow and constitutes a significant, yet often underestimated, mechanism of land degradation. In tropical forested environments, dense vegetation masks surface indicators of subsurface erosion, limiting detection and hindering understanding of pipe development and its geomorphological consequences. This study investigates the spatial organization, controlling factors, and morphodynamic evolution of piping systems in a forested tropical landscape in southeastern Brazil by integrating surface mapping, electrical resistivity tomography (ERT), and soil analyses. Surface indicators of piping were mapped using high-resolution topographic data, while subsurface pipe networks were delineated through ERT surveys. Soil morphology, physical properties, and grain-size distribution were analyzed to identify lithological and pedological heterogeneities associated with preferential flow pathways. The results identified two distinct pipe systems: a shallow network (0.30-0.45 m) and a deeper system (>1.50 m), both consistently associated with high-resistivity zones interpreted as air-filled cavities. These features occur primarily at interfaces between contrasting soil horizons and sandstone lenses of the Itarar´ e Group, where textural discontinuities and clay-enriched horizons form hydraulic barriers and promote lateral subsurface flow. Grain-size statistics and uniformity indices confirmed pronounced vertical heterogeneity associated with parent-material variation, reinforcing the influence of subsurface architecture on pipe initiation and expansion. Surface expressions exhibited clear downslope developmental gradients, with early-stage sagging depressions upslope and interconnected piping-sinkholes and blind gullies downslope. High feature density and rapid morphometric evolution suggest that piping is an active, ongoing process even under dense forest cover. These findings demonstrate that subsurface heterogeneity is a primary control on piping erosion in tropical forest soils and underscore the need to explicitly incorporate subsurface processes into erosion assessment, gully prevention, and land-management strategies.