Pedoenvironments driving the monodominance of Peltogyne gracilipes (Leguminosae) in the Northern Amazon, Brazil

Abstract

Monodominance is unusual in the tropics when compared to the high diversity of tropical forests. Peltogyne gracilipes (Leguminosae) is a deciduous tree species that forms monodominant forests in the Brazilian Northern Amazon region. Initial research confirmed that P. gracilipes monodominance was associated with higher soil magnesium content, while recent studies have indicated a larger number of variables, suggesting a more complex hydro-edaphic habitat. As such, the present study aimed to describe the hydro-edaphic habitat (pedoenvironment) where P. gracilipes is monodominant. Edaphic and topographic variables (drainage proxy) were used in a forest inventory conducted in 129 sampling plots. Trees with a stem diameter greater than 10 cm were analyzed. Aboveground biomass was used as a descriptive variable of the different habitats in the study area. A total of 3041 individuals were sampled (298 P. gracilipes). Multivariate analysis demonstrated that the highest P. gracilipes abundance occurred in poorly drained (seasonal flooding) low-altitude habitats (

Amazon forest biomass: intra- and interspecific variability in wood density drive divergences in Brazil’s far north

“…The eastern portion of Maracá is an ecotone zone characterized by a savanna-forest contact zone where the forest types are determined by different hydro-edaphic conditions (Nascimento et al 2017, Villacorta et al 2022). The forest mosaic as a whole is an accurate representation of the large ecotone forest area in the Northern Brazil-…”

“…were considered to be poorly drained (seasonally flooded), while those at > 65 m a.s.l. were considered to be free of flooding, following the criteria adopted by Villacorta et al (2022) for the eastern portion of Maracá. These categories correspond, respectively, to forests on shallow (≤ 65 m a.s.l.)…”

“…However, higher availability of micronutrients associated with waterlogged tropical soils can reach toxic levels for some plants, conferring more restricted aspects to the habitat (Davies 1997). In addition, areas in the eastern portion of Maracá with higher environmental restrictions are generally populated by Peltogyne gracilipes (Nascimento et al 2017, Villacorta et al 2022), a mon- odominant species characterized by high wood density (0.901 g cm -3 ). The relationship between WD and more/ less restricted environmental characteristics has already been commented on for other regions of the Amazon (Parolin & Worbes 2000, Baker et al 2004, Wittmann et al 2006.…”

“…Recent studies have identified a hydroedaphic gradient acting as an environmental filter that selects tree species, and shapes the ecotone forest's structure in northern Amazonia (Nascimento et al 2017, Silva et al 2021). These ecotone forests occur where there is high environmental heterogeneity that results in a large mosaic of different forest types (ombrophilous, semideciduous and deciduous) (Villacorta et al 2022). This results in forests with structure and floristic composition that are distinct from other Amazonian forests.…”