MULCHING TREATMENT FOR POSTFIRE SOIL CONSERVATION IN A SEMIARID ECOSYSTEM

Fire may generate soil degradation and accelerate erosion processes, d epending among other factors, on the regeneration capacity of the ecos ystem. Conservation measures will be beneficial in those fragile syste ms where a high degradation hazard is estimated. Mulching treatment wa s evaluated in order to establish its efficiency in protecting soil an d preventing runoff generation in a semiarid area affected by a wildfi re. Straw mulch was applied at 200 g m(-2) in three replicated plots. Paired mulched and control plots were established in a three block exp erimental design. Runoff, sediment yield, plant cover, and dynamics of soil physical properties were measured in these plots over a 2-year p eriod. Most of the plant regeneration after the pre resulted from resp routing of the dry grassland species, dominated by Brachypodium retusu m. Total plant cover was only 50% two years after passage of the fire. Runoff and sediment yield were significantly greater from control plo ts. Soil loss from control plots was about 7.2 times higher than the l oss from mulched plots. Surface runoff showed similar differences. Mul ching also reduced surface crusting and slightly stimulated vegetation growth.