Diurnal pattern of leaf extension in Salix viminalis relates to the difference in leaf turgor before and after stress relaxation

Relations between leaf dry weight to leaf area (LWA), leaf nitrogen concentration and irradiance inside a natural canopy were studied in Betula pendula Roth., Corylus avellana L. and Lonicera xylosteum L. In all species, LWA increased with increasing irradiance. Relative variability in LWA was smaller in Betula pendula than in the other two species. In Corylus avellana, LWA also depended on total plant height. Foliar nitrogen concentration (on a dry weight basis) increased with increasing irradiance and LWA in Betula pendula, but decreased in the other two species. The interspecific variation in response to light availability and in nitrogen partitioning may be caused by different light demands or different life forms (trees versus shrubs), or both, of the species examined, and must be considered in contemporary canopy models.