Comparing survival and size of resprouts and planted trees for post-fire forest restoration in central Portugal

Abstract

The post-fire restoration of burned forests in the Mediterranean basin usually involves planting or direct seeding, often neglecting the use of natural regeneration through basal resprouting. This study compared the survival and size of planted and resprouted Fraxinus angustifolia (narrowleaf ash) and Quercus faginea (Portuguese oak) in a burned area in central Portugal, after a 20–22-month growing period. Adult ash and oak trees were burned in a wildfire in September 2003. The survival and height of resprouting suckers were assessed 21 months after fire. Seedlings coming from nurseries were planted in the same area during January to March, both in 2004 and 2005, and their survival and height were assessed 20–22 months after planting. Survival was higher in resprouts than in planted trees in the case of oak (98% against 77% and 67%, respectively, for trees planted in 2004 and 2005) but not for ash (100% against 87% and 97%). Plant height was much higher in resprouts than in planted trees (4–5 times higher in oak; 2–3.8 times higher in ash), and a similar pattern was found for basal diameter (3.5–4.5 times higher in oak; 3–5 times higher in ash). The results suggest that using natural regeneration through resprouting may be a cheaper and more effective technique than planting to restore burned forests with a large proportion of resprouter species, as is the case of many Mediterranean broadleaved forests.