Comparison of post-fire seedling establishment between scrub communities in mediterranean and non-mediterranean climate ecosystems

1 Both fire regimes and the conditions under which fires occur vary widely. Abiotic conditions (such as climate) in combination with fire season, freq uency and intensity could influence vegetation responses to fire. A variety of adaptations facilitate post-fire recruitment in mediterranean climate e cosystems, but responses of other communities are less well known. We evalu ated the importance of climate by comparing sites with mediterranean and su btropical climates. 2 We used paired burned and mature sites in chamise chaparral, mixed chapar ral and coastal sage scrub (California), and rosemary scrub, sand pine scru b and sandhill (Florida), to test whether (i) patterns of pre-fire and post -fire seedling recruitment are more similar between communities within a re gion than between regions, and (ii) post-fire stimulation of seedling estab lishment is greater in regions with marked fire-induced contrasts in abioti c site characteristics. 3 Post-fire seedling densities were more similar among sites within climati c regions than between regions. Both seedling densities and proportions of species represented by seedlings after fires were generally higher in Calif ornia. 4 The only site characteristic showing a pre-fire-post-fire contrast was pe rcentage open canopy, and the effect was greater in California than in Flor ida. Soil properties were unaffected by fire. 5 Mediterranean climate ecosystems in other regions have nutrient-poor soil s similar to our subtropical Florida sites, but show post-fire seedling rec ruitment patterns more similar to the nutrient-rich sites in California. Cl imate therefore appears to play a more major role than soil characteristics .