Pioneer and climax species of tropical wet forest leaf anatomy comparated

Abstract

The survival of forest species in shadowed or sunny environments environments depends on the leaf morpho-anatomic adaptations between the others factors. With the objective of compare forest species from distincts successional processes of the tropical wet forest (Atlantic Rainforest), we search, in light and scanning electron microscopy, the leaves quantitative and qualitative features of four species: Cecropia glazioui Sneth. and Trema micrantha (L.) Blume, pioneer species; Bathysa australis (St. Hill.) Hook ex Sch. and Psychotria nuda (Cham. & Sch.) Wawra, climax species. Fresh material was used and fixed in glutaraldeido 2,5%, in sodium phosphate buffer 0,1M, pH 7,2. For scanning electron microscopy the samples were dehydrated and later immerged in HMDS. The pioneer species, with regard to climax species, present a higher stomatal density, guard cells more length, palisade parenchyma more development and cuticle more thickness. The structural and ultrastructural features, like the cuticular fringe, the hydrenchyma and bigger hairs density, in the pioneer species, are the adaptation proofs to intensive light of C. glazioui and T.micrantha. The results revealed that analysis of only one features can carry out to mistaken interpretation in relating to an adaptation. In this manner we need to take into consideration the set of the quantitative and qualitative features of the leaves outer and inner morphology.