IMMEDIATE EFFECTS OF PRESCRIBED BURNING, CHOPPING AND CLEARING ON RUNOFF, INFILTRATION AND EROSION IN A SHRUBLAND AREA IN GALICIA (NW SPAIN)

The immediate effects of three different fuel management treatments on runoff, infiltration and erosion were evaluated in a mixed heathland in Galicia (NW Spain). The treatments compared were: prescribed burning, shrub chopping and shrub clearing. Rainfall simulations were conducted immediately before and after fuel reduction treatments. A rainfall rate of 67 mm h(-1) was applied for 30 min to each runoff plot. Application of treatments significantly affected runoff and infiltration, but the parameter most affected by treatment was soil erosion, especially after prescribed burning. However, sediment yields measured immediately after treatments were low in all the cases, varying front 32 kg ha(-1) after shrub clearing to 248 kg ha(-1) after prescribed burning. In the rainfall simulation plots subjected to prescribed burning, the maximum temperatures reached at mineral soil surface during bums significantly affected soil losses. The organic layer remaining after treatments and soil moisture contents appeared to be critical variables in controlling runoff and erosion during the first rainfall event following fuel reduction treatments. When the remaining organic layer was removed just after treatments and a new rainfall Simulation was carried Out, mean infiltration rate trended to decrease and cumulative runoff and sediment yield tended to increase. The above information could be useful for determining whether fuel management prescriptions are compatible with fire hazard reduction and soil conservation. Copyright (c) 2008 John Wiley & Soils, Ltd.