VARIATION IN LEAF MORPHOLOGY AND BRANCHING PATTERN OF SOME TROPICAL RAIN-FOREST SPECIES FROM GUADELOUPE (FRENCH-WEST-INDIES) UNDER SEMICONTROLLED LIGHT CONDITIONS

Seedlings of 7 canopy species from the Guadeloupe tropical rain forest (Dacryodes excelsa, Amanoa caribaea, Richeria grandis, Simaruba amara, Symphonia globulifera, Byrsonima coriacea and Podocarpus coriaceus) were raised in full sunlight and under artifical neutral shade transmitting 6, 11, 19 and 54% light for 2 to 3 years. At the end of this period, the number of leaves and branches, leaf size, specific leaf area and stomatal density were observed for each plant. For all species, the maximum number of leaves was obtained in partial shade (11 or 19% sunlight). Branching occurrence depended more on species type than on light conditions. Both individual leaf size and specific leaf area increased regularly with shade; but in a proportion which varied according to the species. Stomatal density was highly variable from one species to another and increased with greater light. The morphological plasticity of species response to light conditions was then analysed and related to shade tolerance. In order of decreasing plasticity, the first species found were R grandis, S amara and B coriacea, which were the most plastic and the most shade intolerant, followed by A caribaea and P coriaceus, less plastic but shade-tolerant species. Finally, D excelsa and S globulifera were found to be the least plastic species and highly or moderately shade-tolerant.