Co-ordinating Editor: Alicia Acosta
Oak trees and soil interactions in Mediterranean forests: a positive feedback model
Article first published online: 11 MAY 2011
© 2011 International Association for Vegetation Science
Journal of Vegetation Science
Volume 22, Issue 5, pages 856–867, October 2011
How to Cite
Aponte, C., García, L. V., Pérez-Ramos, I. M., Gutiérrez, E. and Marañón, T. (2011), Oak trees and soil interactions in Mediterranean forests: a positive feedback model. Journal of Vegetation Science, 22: 856–867. doi: 10.1111/j.1654-1103.2011.01298.x
Aponte, C. (corresponding author, email@example.com); García, L.V. (firstname.lastname@example.org); Pérez-Ramos, I.M. (email@example.com); Gutiérrez, E. (firstname.lastname@example.org) & Marañón, T. (email@example.com): Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, PO Box 1052, E-41080 Sevilla, Spain.
- Issue published online: 1 SEP 2011
- Article first published online: 11 MAY 2011
- Received 2 November 2010, Accepted 28 March 2011
- Biogeochemical niche;
- Ecological stoichiometry;
- Ecosystem functioning;
- Foliar analysis;
- Nutrient cycling;
- Quercus canariensis;
- Quercus suber;
- Soil fertility
Questions: What is the spectrum of variability of chemical elements in a Mediterranean forest ecosystem across the different compartments? Do co-existing tree species with different leaf chemical composition and nutrient cycling distinctly modify soil conditions? Could these species-specific, tree-generated soil changes create a potential positive feedback by affecting long-term species distribution?
Location: Mixed oak forests of southern Spain, Los Alcornocales Natural Park.
Methods: We sampled and chemically analysed five different ecosystem components: leaves, leaf fall, litter and superficial (0–25 cm) and sub-superficial (25–50 cm) soil beneath the canopies of evergreen Quercus suber and deciduous Q. canariensis trees. We used multiple co-inertia analysis (MCoA) to conjointly analyse the patterns of variability and covariation of eight macro- and micronutrients determined in each of the sampled ecological materials. We implemented a path analysis to investigate alternative causal models of relationships among the chemical properties of the different ecosystem components.
Results: Variability in the concentration of chemical elements was related to the nature of their biogeochemical cycles. However, the rank of element concentration was consistent across ecosystem components. Analysis of co-inertia (MCoA) revealed that there was a common underlying multivariate pattern of nutrient enrichment in the ecosystem, which supported the hypothesis of a separation in biogeochemical niches between the two co-existing oak species, with Q. canariensis having richer plant tissues and more fertile soil directly under each tree than Q. suber. The feasibility of a potential tree–soil positive feedback model was the only statistically validated among several alternative (non-feedback) models tested.
Conclusions: In the studied Mediterranean forests, oak species distinctly modify soil fertility conditions through different nutrient return pathways. Further investigation is needed to address whether these tree-generated soil changes could affect seedling establishment and ultimately influence species distribution.