Summary
In this paper, ecophysiological parameters of some Tropical Rain Forest species on terra firme were measured. The data obtained was correlated to the soil descriptions of Falesi et al. (1969), and the inventory of the study area done by Prance et al. (1975). The parameters considered were light, light compensation point, stomatal behavior of species of the lower stratum of the forest, stomatal behavior in relation to water deficit, and the shrinking and swelling of the trunks of some forest species. Light interception by the canopy was determined to be 98.63% with penetrance to the lower stratum (measured at 1.3 m from the ground) of only 1.37% of the light available above the canopy. The leaf area Index was determined as 6,60 m2/m2, within the expected range for this type of forest. It was shown that plants in the lower (shade) stratum were able to photosinthetise with low light intensities (85-575 lux). The data on light compensation points for other canopy layers and emergents showed that for these, photosinthesis ocurred at intensities of between 1.900 and 3.000 lux. It was also shown that stomata of plants on the lower stratum are open during the whole day or most of it, and do not require high light intensities to open. Water loss and uptake in the bark of tree species was also studied, and it was shown that exposure to light, the size of the crown, and the diameter of the trunk have a marked influence on the results. Finally, stomatal behavior was studied, showing that emergents have high stomatal resistence to water loss, while plants in the shade have little stomatal resistence. It was also observed that some shade plants have high stomatal resistence when the stomata are almost closed.