Sclerophylly in beech (Fagus sylvatica L.) trees: its relationship with crown transparency, nutritional status and summer drought

Abstract

Sclerophylly is common in evergreen Mediterranean flora, but can also manifest itself in mesophile vegetation: in those cases it is considered an adaptation to conditions of environmental stress. Sclerophylly is the result of tissue thickening and histochemical alterations (lignification of tissues and accumulation of phenolics), and is a xeromorphic adaptation. According to Guray Kutbay and Kilinc (1994) sclerophyllous adaptations occur as a consequence of nutritional deficiencies, especially shortages of nitrogen and potassium. Such alterations can also be induced by low ozone concentrations (Gunthard-Goerg et al, 1993). It has moreover been suggested that tissue lignification is a non-specific reaction in trees subjected to stress (Vance et al, 1980; Mayo et al, 1992). The accumulation of phenolic compounds also plays an important role in the tree's resistance to adversities (Nicholson and Hammerschmidt, 1992).