Previous land use affects the recovery of soil hydraulic properties after forest restoration

Knowledge of soil hydraulic properties after forest restoration is essential for understanding the recovery of hydrological processes, such as water infiltration. An increase of forest cover may improve water infiltration and soil hydraulic properties, but little is known about the response and extent to which forest restoration can affect these properties. The purpose of this study was to investigate the effect of forest restoration on surface-saturated soil hydraulic conductivity (Ks), and to verify the Ks recovery to the pre-disturbance soil conditions. We sampled field Ks at the surface in Campinas municipality, São Paulo State, Brazil, at 18 plots under three land-cover types: (i) a pasture; (ii) a restored forest using a high-diversity mix of plantings (85 regional native species) of 9 years of age; and (iii) a remnant forest patch. We used the Beerkan method for soil hydraulic characterization. Bulk density (ρb), soil organic carbon content (OC), soil porosity and particle size data were also sampled. We found considerable differences in soil hydraulic properties between land-cover classes. The highest Ks were observed in remnant forest sites and the lowest Ks were associated with pasture sites. The Ks recovery differs markedly between restored forests. Our results strongly suggest that soil attributes and Ks recovery are influenced by the duration and intensity of land use prior to forest restoration. Attention needs to be given to management activities before, during and after forest restoration, especially where the soil is still compacted and Ks is low.