Palm community structure association with topography, hydrography and forest density in a remote site in the Iriri river valley, Eastern Amazon

Background and aims – Palms (Arecaceae) are crucial to Amazonian ecosystems, contributing to biodiversity, ecosystem services, and forest resilience, and providing non-timber forest products (NTFPs) for local populations. This study investigated how topography, hydrography, and forest density influence palm community structure in a remote Eastern Amazon site, addressing knowledge gaps in this region.

Material and methods – A field survey was conducted in 100 plots along a 5 km transect within the Riozinho do Anfrísio Extractive Reserve, Pará, Brazil. Palm species were identified, and topographic and hydrographic data, including NDVI, altitude, proximity to permanent and intermittent streams, and terrain characteristics were collected. Species richness and composition were analysed using Redundancy Analysis (RDA), general linear models (GLM), analysis of variance (ANOVA) and Bayesian regression models.

Key results – Eighteen palm species were recorded, dominated by Attalea speciosa , Geonoma baculifera , and Euterpe longibracteata , providers of NTFPs. NDVI and altitude significantly influenced species composition, with denser forests favouring species such as G. baculifera , while others, such as A. speciosa , were found in less dense areas. The presence of igarapés (shallow, slow Amazonian streams) was the strongest predictor of species richness and composition, favouring E. oleracea and G. baculifera .

Conclusion – Palm community structure in the study area was shaped by environmental gradients, particularly NDVI, terrain shape and proximity to igarapés . These findings highlight the ecological importance of topographic and hydrographic features in structuring palm diversity and offer insights for conservation and management strategies in the Eastern Amazon.