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Canopy with palm grove, French Guiana, southern border in Brazil.. © IRD, Daniel Sabatier

Amazon forest: the first large-scale inventory has revealed the hyper-dominance of 227 tree species

An international study, involving scientists from IRD, INRA, CNRS, CIRAD, with the support of the IRD herbarium in French Guiana, recently produced the first large-scale inventory of the trees in the Amazon Basin. The researchers showed that the world's largest tropical rainforest comprises almost 390 billion trees belonging to some 16,000 species. They demonstrated that just 227 species were hyper-dominant, accounting for more than half the trees in the rainforest. The results of the study, which also estimated the number of rare species at 11,000, were published on 18 October 2013 in the journal Science, in the form of a review paper.

Updated on 07/05/2017
Published on 10/18/2013

227 hyper-dominant species and 11,000 rare species

In an international study, coordinated by Hans ter Steege (Naturalis Biodiversity Center, Netherlands), involving scientists from IRD, INRA, CNRS and CIRAD, with the support of the IRD herbarium in French Guiana, researchers compiled and standardised data concerning the abundance of species for more than half a million lowland forest trees (1,170 one-hectare plots), from the international Amazon Tree Diversity Network (ATDN).

These data were initially used to estimate the total number of trees in the Amazon Basin and tree density on a square degree scale. They were then integrated into an abundance distribution model, to estimate the total number of species in the Amazon Basin and the main regions within it, and the characteristics of species dominance or rarity.

The scientists estimated that the Amazon rainforest comprises almost 390 billion trees of 16,000 different species. They showed that more than half the individuals in the basin belong to just 227 species. Those species, which can be classed as hyper-dominant, are geographically widespread (although they are only dominant in one or two Amazonian regions).

They include palms (particularly Euterpe oleracea, an emblematic species of the Amazon, used in food processing and consumed in the form of an energy drink in several countries in the region), Myristicaceae (nutmeg family) and Lecythidaceae (Brazil nut family). Finally, through this inventory, researchers have identified nearly 11,000 rare species (representing just 0.12% of individuals in all).

Continuing inventories to protect threatened species 

This study demonstrates the uniformity of the forest trees in Amazonia. The hyper-dominance of just 227 species means that bio-geochemical cycles in the Amazon Basin (chemical transport and cyclical transformation) are largely accomplished by a tiny fraction of the range of plants.

Further studies are required to determine the reasons for this hyper-dominance. According to the researchers, such spatial distribution models could be used to predict the structure and wealth of the forest in unexplored areas, and could be improved by taking account of environmental data.

They stress the necessity of stepping up the inventory of the 11,000 rare species. Due to their limited distribution, these species are under severe threat from deforestation and could well disappear before they have even been observed and described. Furthermore, the distribution of abundance demonstrated by the study shows that colossal efforts are required to survey these rare species.

Useful information

The Amazon rainforest is the largest such tropical forest in the world, covering almost 6 million km2 and nine countries (Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Surinam and French Guiana). It is a true biodiversity hotspot for both animal and plant species, and is under substantial pressure from deforestation and other human activity (according to estimates, almost 18% of the rainforest has disappeared since 1970).
Producing an accurate inventory of the tree communities in the Amazon rainforest is a major scientific challenge, with a view to identifying rare species and protecting them from extinction. Despite international efforts over the past thirty years, producing such an inventory for the whole of the Amazon Basin has proved complex and difficult, in view of the vastness of the area to be studied and the record diversity of tree communities (up to 210 species per hectare in Guyana and more than 300 in Peru).

Scientific contact(s):

Press Relations:
INRA News Office (+33 1 42 75 91 86)
Associated Division(s):
Forest, Grassland and Freshwater Ecology
Associated Centre(s):
French West Indies and Guiana


Ter Steege H. et al. Hyper-dominance in the Amazonian Tree Flora. Science, 18 October 2013