Effects of light availability on morphology, growth and biomass allocation of Fagus sylvatica and Quercus robur seedlings

• High survival was found for beech and oak seedlings under different light regimes.
• Growth and biomass decreased as shade increased.
• Both species had morphological acclimation to shade.

The survival, morphological, and growth responses of European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) seedlings to different light intensities, from full sunlight to heavy shade, were studied over two growing seasons in a shadehouse experiment. Although shade treatments significantly affected seedling growth, they did not influence seedling survival. Both growth and biomass increased as light intensity increased. Diameter growth of oak seedlings was higher than that of beech. Beech and oak seedlings showed typical acclimation to shade, including greater specific leaf area and height to diameter ratios, and lower leaf thickness and root:shoot ratios with increasing shade. Beech seedlings exhibited greater specific leaf area, and lower leaf thickness and root:shoot ratios than oak seedlings. In spite of the greater growth at full sunlight, the results from this study suggest that beech and oak seedlings would have high survival rates and would acclimate well if underplanted below overstories that reduce the available light to as low as 28% of full light.