Some ecophysiological features in sun and shade leaves of tall beech trees

Some ecophysiological features in sun and shade leaves of tall European beech trees (Fagus sylvatica L.) growing in a natural forest stand were investigated. Quantitative leaf characteristics were followed in the field and under controlled conditions. In the sun leaves significantly higher rates of photosynthesis, photorespiration and dark respiration, and also photosynthetic CO₂ fixation capacity, photosynthetic productivity, and saturating, adaptation and compensating irradiances were found. Specific leaf mass, mean leaf area, stomata density and size as well as the chlorophyll content per unit dry mass were also significantly different in both types of the leaves. Higher photosynthetic efficiency in the shade leaves allows them a better utilization of the lower irradiance for carbon dioxide uptake. The importance of these findings for annual carbon gain of the shade tolerant European beech species is also discussed.