Effect of light and soil moisture on physiological variables in six Mediterranean forest species planted under a pine forest canopy

Introduction: Resprouter species, by regenerating rapidly, can maintain an optimal carbon balance and improve the resilience of ecosystems that have been disturbed or are at high risk of fire. Objective: To assess the effect of light availability and soil moisture on the ecophysiological variables of six resprouter species planted under cover of Pinus halepensis Mill. Materials and methods: Arbutus unedo L., Rhamnus alaternus L., Quercus ilex L., Quercus faginea Lam., Fraxinus ornus L. and Acer granatense Boiss. were planted in plots with three pine densities per hectare: HD = 800 to 1 100, MD = 300 to 600 and LD = 100 to 250. The species were also grown in the nursery, trying to maintain the same solar radiation conditions. Photosynthesis (A), stomatal conductance (Gs), photosystem II maximum efficiency (Fv/Fm) and water use efficiency (IWUE) were measured. Results and discussion: Evergreen sclerophyll species (A. unedo, R. alaternus and Q. ilex) showed higher photosynthetic capacity, lower photoinhibition and lower IWUE than deciduous species. In HD, plants showed lower photosynthetic capacity (P < 0.01) and higher photoprotection (P < 0.001). The IWUE was similar under the three pine forest densities. In the nursery, A was high under 100 % and 50 % light conditions; Gs was higher under 20 % conditions; and IWUE was high under 100 % light. Conclusion: The physiological variables of the species were conditioned by shading and changes in water demand produced by tree cover.