We examined the influence of the seasonal climate on LAI and Canopy
Openness in a mature forest stand and in a forest remnant of the Brazilian Atlantic Forest in Rio de Janeiro. We recognised a significant variability of LAI / Canopy Openness between the central parts and the border region of the forest fragment. There was no comparable variability in the mature forest. In the forest fragment we recorded a highly significant increase of LAI with a mean of 0.45 which is about 12% at the end of the wet season. The higher influence of seasonality on LAI/Canopy Openness resulting in perspicuously higher within-canopy dynamics in the forest remnant have been put down to a structural response to temperature and absolute humidity, due to the low species diversity and a higher abundance of deciduous tree species. The high species richness in the mature forest site with a lower abundance of deciduous pioneer species may prevent such impact on the canopy structure and its spatiotemporal dynamics. We observed an obvious “edge effect” according to the structural changes by the seasonality in Canopy Openness: decreasing difference of Canopy Openness with increasing distance from the edge. A possible reason could be the distribution of deciduous tree species in the fragment with concentration on the forest edge. There was no such effect in LAI, which demonstrates that there is no conclusive dependency between LAI and Canopy Openness.