Demographic and growth rings data of Pentaclethra macrolona in the Amazon River estuary

Little is known about the natural history of the hyperdominant Amazonian tree Pentaclethra macroloba. It has multiple uses and is widely explored, due to the important phytotherapy properties of the oil of its seeds. We determined the demographic and growth patterns of P. macroloba and analyzed the influence of the daily tide in its growth trajectory. We studied populations of P. macroloba in the APA and CEM, northeast of the Brazilian Amazon. In 136.59 ha of the APA, all adult trees with diameter ≥ 5 cm were quantified and two plots of 1 ha each were installed for sampling of the regeneration (diameter < 5 cm). Samples of the radial wood of 38 trees were obtained to determine age and growth rates, through dendrochronological analyzes. In CEM, exchange activity of 30 trees, at different topographic levels, was monitored by dendrometer bands. The effect of precipitation, temperature and flood on the exchange activity of P. macroloba was evaluated using multiple regressions. We model the growth of the species based on the widths of its growth rings. We invented 2,072 adult trees (15 individuals ha^-1), distributed in 12 diametric classes (log-normal pattern), mean diameter of 23 cm, total basal area 98.13 m², height mean of 12.7 m and aggregate distribution pattern (R = 0.63, p <0.002). 240 regenerants (120 individuals ha-1) were quantified, distributed in nine diametric classes (negative exponential pattern), mean height of 0.63 m and aggregate pattern. Growth rings formed by marginal parenchyma show maximum age of 102 years and mean of 60 years for P. macroloba. The relationship between age and diameter was highly significant (r² = 0.98; p <0.001), as well as the relationship between height and diameter (r² = 0.79; p <0.001). The growth models show increment peaks in diameter and height at the age of 46 years (9.38 mm year^-1) and 20 years (48.2 cm year^-1) respectively. Greatest accumulation of biomass occurred at the age of 66 years (40.8 kg year^-1). P. macroloba presents exchange dormancy in the rainy season (t = -2.62; p <0.01) and of river flooding (t = -3.01; p < 0.01). The existence of rings in P. macroloba is an important discovery, as only Mora paraensis had growth rings record in the Amazon estuary. The structural and growth patterns of P. macroloba are reflections of its life history and interactions with the environmental dynamics of estuarine floodplain.