Deer exclusion is necessary to promote post-fire herbaceous regeneration in the understorey of a Mediterranean forest

The frequency of severe wildfires is on the rise in the Mediterranean Basin as a result of climate change and land abandonment. Recurrent wildfires may retard or impede ecosystem recovery, frequently requiring the implementation of restoration practices. In that context, a post-fire deer exclusion experiment was conducted in a Mediterranean mixed forest ecosystem with high population densities of deer species (Fallow deer and Red deer). A deer exclusion area was established as a form of restoration intervention to promote post-fire vegetation recovery. We surveyed plant species during the second and third springs after fire in both deer-excluded and deer-allowed areas in order to detect changes in the community. We analyzed the plant species composition, species diversity, and structure of herbaceous and woody plant communities. We also compared the frequency of annual and perennial herb species, functional groups, and post-fire plant regeneration strategies. The main differences were due to differences between springs rather than of deer-excluded and deer-allowed plots. Deer consumed both woody and herbaceous species, favoring the assemblage of herbaceous over woody species. Deer favored the establishment of annual forbs, including unpalatable and/or exotic species, while limiting the abundance of graminoids. Observed deer impacts could have been magnified during the second spring by a drought. Our study demonstrates that deer exclusion can be an effective restoration practice for promoting post-fire herbaceous regeneration in forests with significant densities of wild ungulates, although seasonal effects may override restoration practice effects.