“Fire seeders” during early post-fire succession and their quantitative importance in south-eastern Spain

According to a quantitative plot-based vegetation analysis we then compared the coverage of “fire seeders” on (a) fire sites at the coast (2-3 years old) with sites of similar age in the mountains and (b) fire sites in the mountains of mid-successional stages (7-9 years) with undisturbed reference sites and areas of different types of disturbance (i.e. logging and fire break areas) but of comparable age and location. Results of comparison (a) showed that “fire seeder” coverage is below 4% and even lower in the coastal area. Comparison (b) showed similar coverage (about 15%) of “fire seeders” on the fire sites and on the fire breaks (strongly disturbed sites) whereas their abundance on logging and undisturbed reference sites was significantly lower. Thus, the term “fire seeder” might be misleading as fire impact is not essential for inducing germination of heat-triggered seeds. In south-eastern Spain, the low abundance of “fire seeders” and their successful regeneration on other disturbed sites are in line with historically early and strong human disturbance and low fire frequencies as the fuel load is limited due to the dry conditions. The tested species are not dependent on a certain regular fire impact though strong disturbance is very favourable for the creation of dense populations.