Ecophysiology parameters of four Brazilian Atlantic Forest species under shade and drought stress

The Brazilian Atlantic Forest has experienced a reduction in its original area since the discovery of Brazil. Over the last 30 years, studies and techniques for forest recovery have advanced. Establishing a self-sustainable reforested area with adequate biodiversity is the main parameter for any reforestation program. Thus, knowledge of the ecophysiological behavior of the species to be used is crucial. Our hypothesis is that certain tools are efficient in determining the ecophysiological characterization of native species within different functional groups. Filling group plants show fast growth, intense gas exchange, present mechanisms of water deficit tolerance and show high efficiency in radiation capture, so they are first planted in a reforestation area. While plants pertaining to the diversity group do not exhibit these characteristics, thus are plants after the establishment of the first group of species. To test this hypothesis, two experiments were installed using young plants of four species native to the Atlantic Forest, grown in 9-L pots. Leaf water potential, gas exchange, chlorophyll fluorescence and certain biochemical parameters of leaf metabolism were evaluated. In the first experiment, plants were maintained under two forms of light availability for 15 days, full light (control) and shaded (shade). The species Inga sp. and Brosimum guianensis presented the most contrasting responses on day 15, principally in the variables leaf water potential, gas exchange, leaf soluble sugar content, F_\textv^￠ /F_\textm^￠ F_{\text{v}}^{\prime } /F_{\text{m}}^{\prime } and F _v/F _m. In the second experiment, plants were divided into two groups: a well-hydrated group (control) and one that underwent irrigation suspension for 7 days (drought); measurements were performed on day 8 of drought. Again, Inga sp. and Brosimum guianensis plants showed responses characterizing them as pertaining to distinct functional groups for the experimental parameters previously described. Thus, Inga sp. was classified as pertaining to the filling group and B. guianensis to the diversity group. The performance of the species Cinnamomum zeylancium and Tapirira guianensis under the conditions studied suggests that these are intermediate species with potential for use as filling group species.