EFFECT OF MEDITERRANEAN SHRUB ON WATER EROSION CONTROL

In the Spanish Mediterranean environment, scrub vegetation occupies a greater area than does forest. The impact of wildfire on the scrub veg etation and recovery afterward affects a number of other processes, in cluding water erosion. While recovered vegetation considerably influen ces soil protection and erosion control, this function has scarcely be en studied. This study discusses the behavior and architecture of reco vering (or regenerating) typical Mediterranean shrub vegetation and th e subsequent impact on soil protection. The study compared two protect ive forage species (Medicago arborea L. and Psoralea bituminosa L.). T he research was performed in field conditions on a set of four experim ental plots. A control plot was maintained with no vegetation cover. R unoff and soil loss by water erosion between 1989 and 1992 were studie d on each of these plots. The natural vegetation was found to have a m ore significant protective effect (69.2% decrease in soil loss) than t he other species tested. Soil loss on the Medicago plot decreased by 4 1.7%, and soil loss on the Psoralea plot decreased by 29.3%. That the Psoralea was only recently planted must be considered in evaluating it s protective effects.