Variability in leaf and crown morphology correlated with light availability in five natural populations of Quercus castaneifolia C.A. Mey

In this study, we investigate seedlings of Quercus castaneifolia C.A. Mey, from five different provenances for the research on leaf and crown morphological variations in relation to a light gradient under controlled conditions in a greenhouse. The results show that significant variations occurred in many parameters due to the effects of light availability. The seedling responses to low light include the proportional allocation of more biomass to leaves, leading to higher leaf mass, leaf area, crown area, specific leaf area and leaf area ratio, in contrast, the seedlings grown in high irradiance faced a high temperature resulting in higher transpiration. At this period, seedlings alter their leaf and crown size to prevent overheating. In this experiment, in spite of the same treatments in controlled conditions in a greenhouse, the seedlings from different provenances indicate different responses to light levels. It seems that the seedlings try to maximize their surface area for the intake of light as the most limiting resource in wet provenances. Such responses under the same treatment are adaptive strategies which allow oak seedlings to have the best function under stressed conditions. For Q. castaneifolia as a species with broad fundamental niches in Hyrcanian forests, these variations may be achieved by a combination of genotypic differentiation and phenotypic plasticity.