Influence of vegetation recovery on water erosion at short and medium-term after experimental fires in a Mediterranean shrubland

摘要

This paper reports the influence that vegetation recovery has exerted on the soil behaviour to erosion by water during both the first and eight years after experimental fires. The work was carried out at La Concordia Experimental Station (Valencia, Spain), which includes nine plots (4 m wide x 20 m long) installed on a calcareous hillside representative of Mediterranean shrubland areas. In June 1995 a set of experimental fires were carry out at two intensity levels (high and moderate) with three plots replication for each treatment. The remaining three plots were used as the control. Rain events between June 1995 to June 1996 and from June 2002 to June 2003 were monitored and their effect on soil erosion processes determined. The vegetation changes(biomass amount and plant cover) for each studied period were also assessed. Total runoff and sediment yield measured during the first post-fire year was 19.43 L m~(-2) and 561 g m~(-2) in the intense fire, and 14.72 L m~(-2) and 326 g m~(-2) in the moderate one, which contrasts with the very low runoff (3.82 L m~(-2)) and soil loss (8.56 g m~(-2)) in control plots. Eight years after the fire, the amount of vegetation on the burned plots represents between 63 and 69% compared to the biomass present before the fire in 1995. The regeneration of plant cover, up to 30-40% eight years after the fire, facilitated a decrease in the difference of soil losses between fire treatments and between burned and unburned plots. However, runoff generation still remainsgreater in burned plots than in the control ones eight years after the fire.