Regeneration after wildfire in communities dominated by Pinus pinaster, an obligate seeder, and in others dominated by Quercus pyrenaica, a typical resprouter

The effects of wildfire on vegetation regeneration in communities dominated by Quercus pyrenaica and those dominated by Pinus pinaster in NW Spain were compared. In order to study changes in the composition and structure of both types of community, permanent plots were established in areas dominated by Q. pyrenaica and those dominated by P. pinaster. All were burned by wildfires at the end of summer. In each plot a permanent transect of 20 m x I m was established. Basal cover of the plant species present was analysed. In both types of community the global cover values generally increased throughout the study period. In the oak communities the species that appear in the first years are those that will dominate in the mature stage, like Q. pyrenaica and Erica australis. Both species are typical resprouters: from shoots on the rhizome or the stem of subterranean roots in the case of Q. pyrenaica and from lignotubers in the case of E. australis. Among the other species, herbaceous perennials dominated during the first year after the fire, Luzula lactea being the most representative. The percentage of bare soil decreased very rapidly after the first year of regeneration. However, in the P. pinaster communities the species that appeared with higher cover values during the first and second year after fire were seeders, like R pinaster and Halimium alyssoides. Other species that appeared in these communities were Chamaespartium tridentatum, and E. australis. Amongst the herbaceous perennials, the most representative species was the Liliacea Ornithogalum umbellatum, which appeared throughout the study period in all the burned plots. The percentages of bare soil were higher than in the oak communities. Structural parameters such as diversity and specific richness were much higher in the community dominated by oak than in the pine stand. In general, regeneration after wildfire in the Pinus community was slower than in oak communities. (C) 2003 Elsevier Science B.V. All rights reserved.