The Amazon rainforest, a vast expanse stretching across nine countries, holds the greatest concentration of biodiversity on Earth. Scientists estimate this colossal ecosystem contains approximately 390 billion individual trees. This immense population is divided among an astonishing variety of species, with current estimates suggesting around 16,000 tree types thrive across the basin. The challenge for researchers has been to move beyond cataloging the total number of species to identifying which single species is the most numerically abundant.
The Challenge of Counting Millions of Trees
Determining the most common tree in the Amazon required a basin-wide count, moving far beyond local surveys due to the forest’s massive size. The scientific effort involved a meta-analysis, combining data from numerous independent studies. Over 100 experts pooled information from 1,170 forest plots established across the region.
This large-scale data collection allowed researchers to focus on numerical abundance—the total count of individuals for each species—rather than just species richness. Using mathematical models, they extrapolated from the inventoried plots to estimate the total population of all tree species across the entire Amazonian landscape. The resulting figures revealed a significant contrast between the many rare species and the few dominant ones.
Identifying the Amazon’s Most Common Tree
The research identified a single palm species, Euterpe precatoria, as the most common tree in the Amazon basin. This palm is a relative of the more widely known Euterpe oleracea, or açaí palm. Scientists estimate its total population to be approximately 5 billion trees across the region.
Despite this enormous number, Euterpe precatoria still only accounts for just over 1% of the estimated 390 billion trees in the Amazon. This numerical dominance highlights a pattern of uneven distribution within the forest’s immense diversity. Euterpe precatoria is often colloquially referred to as forest açaí or single-stem açaí in some regions.
Ecological Success of the Dominant Species
The success of Euterpe precatoria is attributed to its adaptability and specific biological traits. This species is a slender, tall-growing palm that typically features a solitary stem, distinguishing it from related palms that grow in clusters. It can tolerate shade in its early stages, allowing young palms to establish themselves in the dimly lit understory of the mature forest.
The palm thrives in a variety of Amazonian microhabitats, including lowland rainforests, swamps, and river floodplains. Its fruit, a small, dark drupe, is a food source for numerous seed dispersers, such as birds, rodents, and mammals. This efficient dispersal mechanism allows the palm to colonize new areas effectively and maintain a wide geographic distribution.
The Concept of Hyperdominance in Amazonia
The abundance of Euterpe precatoria is an example of hyperdominance, an ecological concept describing the uneven distribution of individual trees among the Amazon’s many species. While the forest is home to approximately 16,000 tree species, a disproportionately small group accounts for half of all individual trees.
Researchers classified 227 species, representing only about 1.4% of the total species richness, as hyperdominant. This small group performs a large share of the forest’s ecological functions, such as biomass production and carbon cycling. Other dominant species include the palm Oenocarpus bataua and the large canopy tree Iriartea deltoidea. Hyperdominance shows that the Amazon is hyper-diverse in species count, yet numerically dominated by a few successful types.