Regeneration of Mediterranean forests is severely limited. Multiple abiotic factors are known to constrain the establishment of woody seedlings at its first phases, such as summer drought or excessive incident radiation, but less attention has been paid to the role of intra-specific variation in seedling performance. In this study we investigate the relative influence of environment (light availability, soil moisture and summer irrigation) and intrinsic factors (seed mass and maternal origin) as determinants of within-population variability in the early establishment of four coexisting Mediterranean oaks (Quercus ilex, Quercus suber, Quercus faginea and Quercus pyrenaica), from emergence and early growth to second-year survival in a field experiment. Seed size was a poor predictor of seed and seedling success. Instead, mother identity showed a stronger effect on seedling performance. Time and percentage of emergence, establishment success and morphological traits varied among seedlings from different maternal trees but main drivers for each variable were different for each species. In addition to a direct effect, in many cases mother-related intrinsic traits and seed mass influenced the effects of environmental conditions on seedling performance. The role of intrinsic factors was masked under ameliorated conditions (i.e. summer irrigation), indicating the relevant role of within-population variability to cope with highly heterogeneous and unpredictable Mediterranean environments.
Bibliographical noteFunding Information:
This study was supported by a predoctoral fellowship FPI-MEC to V.G-R ( BES-2006-13059 ) and by the coordinated Spanish MEC project DINAMED ( CGL2005-05830-C03-02/BOS ), INTERBOS ( CGL2008-04503-CO3-02 ), DIVERBOS ( CGL2011-30285-C02-02 ) and FEDER funding. We thank R. Casado who gave us field assistance and to José Manuel Quero, Pedro Lara, Fernando Puig and Bartolomé Arévalo for their facilities and help during the selection of mother trees and seed collection in Natural Park “Sierra de Cardeña y Montoro” (Córdoba, Spain). We thank the comments of Jacqui Shykoff and two anonymous reviewers on a previous version. Our research group is a member of the GLOBIMED network.
- Aboveground biomass
- Mother plant