MORPHO-ANATOMICAL ALTERATIONS IN LEAVES OF FAGUS-SYLVATICA L. AND QUERCUS-ILEX L. IN DIFFERENT ENVIRONMENTAL-STRESS CONDITION

By means of anatomical and foliar structure observations, this paper e xamines the ecological behaviour of two different species of broadleaf (a mesophile one, beech, and a xerophile one, helm-oak), under differ ent conditions of water supply. The purpose of this study was to evalu ate their response in relation to possible climate changes. The result s highlight certain similarities of behaviour (reduction of leaf surfa ce, increased leaf thickness, increase of mechanical structures in xer ic stands). The main difference between the two species lies in the ta nnins content, which increase in the epidermal cells (vacuoles and wal ls) only in beech trees in xeric conditions. (C) 1998 Elsevier Science Ltd.