Arranjos funcionais de Macrolobium Schreb. (Fabaceae) em distintas tipologias de áreas úmidas da Amazônia Central

Abstract

This study investigated the functional diversity of congeneric species of Macrolobium Schreb. (M. duckeanum and M. bifolium) in different wetland habitats (campinarana, igapó and baixio) in Central Amazonia. Functional characteristics related to the anatomy, structure and growth of the wood were used. Monitoring of the diametric increment rate and monthly phenology was carried out to discover the rhythm and period of growth in each habitat. Hydrological, climatic and edaphic data were used to characterize the environmental gradients. It was possible to indicate the arrangements of functional characteristics that congeneric trees use to adapt to the different environmental conditions specific to each forest. The trees of white-sand ecosystem are more vulnerable to water deficit, generating implications in anatomical structures through the construction of larger vessels (Hydraulic vessel diameter – DhV: 14.32 ± 1.66 μm), high wood density (0.72 ± 0.04 g / cm3) and low height:diameter ratio (0.60 ± 0.07 m/cm). While trees growing in the seasonal black-water floodplain and riparian forest are more vulnerable to anoxic conditions, reflected by the formation of smaller vessel structures (DhV: 11.67 ± 1.48 μm e DhV: 9.96 ± 2.09 μm), lower wood density (0.52 ± 0.01 g/cm3 and 0.65 ± 0.06 g/cm3) and higher ratios of height:diameter (0.90 ± 0.09 m/cm and 1.13 ± 0.13 m/cm). The obtained results suggest that the congeneric tree species developed in each habitat specific arrangements of functional characteristics, turning the trees well adapted to the distinct environmental conditions to each location. This interaction between the different functional arrangements in contrasting environments does not significantly influence the mean diameter growth rates of the congeneric pairs (Diametric average increment – IMDcampinarana = 2.88 ± 0.43 mm/year, IMDigapó = 2.81 ± 0.89 mm/year, and IMDbaixio = 2.23 ± 0.61 mm/year).