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

Abstract

The present study investigates long-term changes 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 g m⁻² h⁻¹, 6 months after the fire under wet-winter conditions, declining to 30 g m⁻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.