Shrub recovery after fuel reduction treatments and a subsequent fire in a Spanish heathland

Abstract

Fuel reduction treatments are commonly used nowadays to reduce wildfire hazard in northwestern Spain. Although prescribed fire has been widely used as a fuel reduction treatment, comparison with mechanical methods is scarce. In this study, we compared the effects of prescribed burning, clearing and mechanical shredding on shrub cover recovery, relative to untreated mature vegetation, in a heathland dominated by Erica umbellata Loefl. (L.) in Galicia (NW Spain). The fuel reduction treatments were applied in the spring of 2006, and the area was burned by an experimental fire in the spring of 2009. We evaluated shrub recovery, in comparison with an untreated control, after application of the above-mentioned fuel reduction treatments and also after an experimental fire 3 years later. Shrub cover and height remained lower than in the untreated control during the 3 years after application of the treatments, and the effects of the different treatments were not significantly different. The treatments did not affect species richness or seedling density during the 3-year interval. After the experimental fire, the only significant effect observed was an increase in grass cover in the areas treated by mechanical shredding and by prescribed fire relative to the control (untreated area); this effect lasted until the end of the study. Some consequences for management of this type of heathland are also discussed.