Oak trees and soil interactions in Mediterranean forests: a positive feedback model

Abstract

What is the spectrum of variability of chemical elements in a Mediterranean forest ecosystem across the different compartments? Do coexisting tree species with different leaf chemical composition and nutrient cycling distinctly modify soil conditions? Could these species-specific, treegenerated soil changes create a potential positive feedback by affecting longterm species distribution? 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.