Heat and smoke as germination cues in the Mediterranean flora
Until now, the role of fire as a germination cue for Mediterranean Basin plants was unclear. The idea was that heat stimulates germination mainly in Cistaceae and Fabaceae and that smoke had a limited role as a post-fire germination cue, in comparison to other Mediterranean Type Ecosystems (MTE), suggesting that fire-stimulated germination is less relevant in the Mediterranean Basin than in other Mediterranean regions. However, in a recent paper, Moreira et al. (2010) demonstrate that both heat and smoke stimulates the germination (both amount and rate) of a range of woody species from the Mediterranean Basin flora. In addition, some species also showed enhanced seedling growth after the smoke treatment (Figure below). All these results suggest that fire-cued germination in woody plants of Mediterranean Basin may be as important as in other Mediterranean regions, and that fire had a strong role in shaping the Mediterranean species.
Differences in size between seedlings from untreated (control, left) and treated seeds (smoke, right), for Lavandula latifolia (8 days after seedling emergence). The white squares are of 2.5cm width. (Photo: B. Moreira).