The agreement of biophysic interaction between phosphorus accumulative species, such as Neea macrophylla and Cecropia palmata with radiation and water available in secondary forests in the Northeast of Pará, becomes essential for the composition of Agroforest Systems and enriched Forests. The objective of this research was to identify how much radiation (PAR, BAR and PhyAR) crossed over to the canopies of the species studied, taking into consideration the tree aggregation density and distance from the soil, as well as the water behavior by determining the Water Potential (predawn and midday) in different climatic periods. The results showed that Cecropia palmata had the highest irradiances, independent of tree aggregation, suggesting better conditions for photosynthetic and morphogenic processes of the species that comes under the influence of its canopies. In respect to water behavior, a clear stratification between three species was observed, where Cecropia palmata was the species that developed the highest water potential midday, signaling fantastic tolerance to dry periods and consequently maintaining a more stable turgidity condition, which is essential to the photosynthetic process, while Casearia arborea can be considered the more sensitive, for it reached a very negative Water Potencial (y). The effect of the climatic period on the Water Potential determined their reduction for all species in the months with less pluviometric precipitation
water potential; Photosynthetically Active Radiation (PAR); Blue Active Radiation (BAR); Agroforest Systems
