Regeneration ecology of Quercus Suber (cork oak) in Southern Spain

Resumen

The success of natural regeneration in forests depends on the sequential and complete achievement of several connected lift-history stages of tree species. The collapse of any stage results in the limitation of the overall recruitment process. In this study, we focus on several regeneration stages of the cork oak (Quercus suber) tree species: seed production, pre-dispersal and post-dispersal predation rates, and establishment of seedlings. The fieldwork was carried out at three forest plots located within Los Alcornocales Natural Park (Southern Spain) where Q. suber is dominant. We have monitored seed production of 50 adult trees during three consecutive years, estimating, the proportion of crop loss due to abortions and to damage by insect larvae. We have also studied the impact of predators (rodents and large herbivores) on seed survival in different types of microsites. Finally, we have studied the effect of microsite types and environmental factors (light, soil moisture and soil compaction) on the germination of sown seeds and the subsequent emergence and survival of seedlings. Results suggest that the high acorn predation rates (both pre-dispersal and post-dispersal) and the high mortality of seedlings (during the summer drought) are main causes of limitation in the natural regeneration of Q. suber in the study area. These factors act on a microsite-depending scale, altering acorns and seedlings probability of survivorship. The scientific knowledge of natural regeneration requirements of Q. suber will help to develop ecological restoration programs in disturbed areas caused by fire, tree disease, or changes of land use.