PARENT SESSION
Oral Session #49: Restoration Ecology. Presiding: J. Callaway.
Wednesday, August 8, 2001. 1:00 PM to 4:30 PM. Madison Ballroom D.
Ontogenetic development of sun and shade leaves in tropical tree species.
MARTINEZ-GARZA, CRISTINA1, HOWE, HENRY1, 1
ABSTRACT- An important task for conservation is the maintenance and enlargement of remnant forest areas. The planting of long-lived trees is useful since they offer resource and structural diversity to animals and other plant species. However, the success of long-lived trees in open areas will depend on their capability to overcome adverse environmental conditions, particularly light availability. Although mature long-lived trees produce sun and shade leaves in the upper and at the bottom of their canopy respectively, it is not known whether this change in leaf characteristics is ontogenetically fixed for adult stage. In this study we compare morphological leaf traits in 8 tree species at the seedling, juvenile and adult stage within the northernmost tropical rain forest (Los Tuxtlas region, Southeast Mexico). Higher Leaf area, SLW, and SLWC were detected among leaves from adult plants (70.3 ± 5, 86.4 ± 2.5, 123.6 ±4 respectively) compared with leaves from seedlings (42.3 ±5, 63.2 ±2.2, 75.1 ±5 respectively). The same pattern was observed between sun and shade leaves. Although most of the leaf traits evaluated showed higher values at the adult stage, the magnitude of leaf differentiation between sun and shade environments was irrespective of ontogenetic stage. Even when other factors may constrain seedlings to produce leaves like adults, seedlings of long-lived trees may be able to adjust leaf morphology to growth in open areas.
KEY WORDS: leaf mass per area, ontogeny, tropical trees, Los Tuxtlas