Effects of Quercus suber decline on woody plant regeneration: potential implications for successional dynamics in Mediterranean forests.
Ibáñez, B., Gómez-Aparicio, L., Ávila, J. M., Pérez-Ramos, I. M., & Marañón, T.
In the last two decades, widespread tree decline and mortality have been documented in forests worldwide. These mortality events usually show certain level of host-specificity, translating into ra- pid changes in the relative abundance of the adult community. Despite these short-term changes, it is poorly understood whether the decline and mor- tality of certain tree species are likely to result in long-term vegetation shifts. Trajectories of forest recovery and the probability of occurrence of per- manent vegetation shifts are to a large extent determined by post-mortality regeneration dynamics. Using a spatially explicit neighborhood approach, we evaluated the spatial patterns of natural regeneration of the woody plant commu- nity in mixed Mediterranean forests affected by the decline of their dominant tree species, Quercus suber. We predicted the abundance, survival, and richness of the seedling and sapling bank as a function of the distribution and health status of the tree and shrub community. Results indicated that Q. suber decline had detectable effects on seedlings and saplings of coexistent woody species from very different functional groups (trees, shrubs, and lia- nas). The sign and magnitude of these effects varied substantially among coexistent species, which could imply shifts in the species ranking of seedling and sapling abundance, affecting successional tra- jectories and potentially leading to vegetation shifts. Because most of these changes pointed to- wards a loss of dominance of Q. suber, management strategies are urgently needed in order to attenuate adult mortality or promote its regeneration, coun- teracting the negative effects of global change dri- vers (exotic pathogens, climate change) on these valuable forests.