Influence of vegetation recovery on soil hydrology and erodibility following fire:: an 11-year investigation

The present study investigates long-termchanges in soil hydrological properties and erodibility during the regrowth of different types and densities of vegetation following a severe wildfire in the Serra Grossa Range, eastern Spain. Twelve plots of similar slope and soil characteristics, naturally recolonized by four different plant species ( trees, herbs, shrubs and dwarf shrubs) were examined using rainfall simulations during an 11-year period. The mean erosion rate was 80 gm(-2) h(-1), 6 months after the fire under wet-winter conditions, declining to 30 gm(-2) h(-1) in the following summer and reaching < 10 g m(-2) h(-1) after 2 years. Considerable variation under the different vegetation types was observed. Herbs and shrubs reduced erosion and overland flow coefficients to negligible values 2 years after fire, whereas under trees and dwarf shrubs, appreciable overland flow and soil loss still occurred after 5 years. On tree-covered plots ( Pinus halepensis), overland flow actually increased over time in association with the development of topsoil hydrophobicity, reaching a coefficient of 27% 10 years after burning. Rates of post-fire overland flow and erosion reduction were strongly influenced not only by vegetation coverage but also by the type of cover and its effects on soil hydrophobicity.