Canopy water delivery and soil physical–hydrological functioning across forest restoration and Eucalyptus stand-development stages in a Cerrado–Atlantic Forest transition

Abstract

Understanding how vegetation cover, stand development, and prior land-use history are associated with soil physical–hydrological functioning is essential for interpreting runoff regulation in human-modified tropical landscapes. We evaluated rainfall delivery to the soil surface, soil physical condition, infiltration, and surface runoff across five vegetation conditions in a Cerrado–Atlantic Forest transition in southeastern Brazil: a native forest remnant, two enriched restoration stands, and two Eucalyptus plantations representing contrasting stages of stand development and land-use trajectories. Open rainfall and throughfall were monitored over an annual cycle, while soil water content, bulk density, total porosity, soil penetration resistance, infiltration rate, and surface runoff were repeatedly measured in replicated plots. These indicators were further integrated into a standardized Soil Physical Infiltration Potential Index (SPI) to summarize infiltration-favorable versus restrictive soil states. Throughfall increased linearly with rainfall in all vegetation conditions, but cumulative throughfall-to-rainfall ratios differed among covers, indicating contrasting canopy water-delivery patterns. Soil physical indicators showed clearer separation among vegetation conditions than surface runoff alone. The native forest remnant exhibited the most favorable soil conditions, with higher soil water content and total porosity and lower bulk density and penetration resistance, and also showed the highest SPI. In contrast, the younger Eucalyptus stand exhibited the most restrictive conditions and the lowest SPI, while the restoration stands and the 39-month Eucalyptus stand occupied intermediate positions. Seasonal effects were most consistent for soil water content, which was higher during the wet season across all land covers, whereas seasonal changes in bulk density, porosity, and penetration resistance were less uniform. Surface runoff was generally low and highly variable. Rainfall supply was a significant positive predictor of runoff, whereas adding SPI provided little additional explanatory power beyond rainfall and land cover. The observed soil-state contrasts were associated with vegetation condition and stand development within a landscape characterized by contrasting prior land-use histories. These results indicate that multimetric soil diagnostics can improve the interpretation of near-surface hydrological functioning across forest restoration and plantation systems, while event-based approaches incorporating rainfall intensity, antecedent wetness, and hydrological connectivity are needed to better resolve runoff responses.