Postfire effects on soil properties and nutrient losses

The effects of an August, 1992, wildfire on nutrient losses by water erosion have been studied. The fire affected an area of 9498 ha of pine forest and shrub, located in Sierra Calderona (Valencia, Spain). In the burned area, six stations of erosion measurement were set up immediately after the end of the fire. The results obtained in these stations are reported. Topographical, edaphological and vegetation characteristics of each station are described. Fourteen episodes of erosive rain with production of runoff and sediments, between August,1992, and November, 1993, were studied, mainly in relation to changes in the soil chemical characteristics. Data show that the highest soil and nutrient losses were produced in the period immediately after the fire. However, fire intensity is the factor that determines the soil status with respect to its response to nutrient losses.