Calculated for the first time: half of all of 400 billion trees in the Amazon are made up of just 227 species
Important implications for nature conservation
Of the nearly four hundred billion trees of the Amazon, half are made up of just 227 hyperdominant species. This is just 1,4% of the total number of 16.000 species estimated. Researchers, taxonomists, and students from 120 institutions around the world have provided new answers to two simple but long-standing questions about Amazonian diversity: How many trees are there in the Amazon, and how many tree species occur there? The study will be published October 17, 2013 in Science.
“The most common species now have a name”
Surprisingly little is known of the Amazon Basin, the area with the richest plant biodiversity on earth. The vast extent and difficult terrain of the Amazon Basin (including parts of Brazil, Peru, Columbia) and the Guiana Shield (Guiana, Suriname, and French Guiana) has historically restricted the study of its extraordinarily diverse tree communities to local and regional scales.
Now, however, over 120 experts on the Amazon, led by Hans ter Steege of Naturalis Biodiversity Center and Utrecht University, the Netherlands, have contributed data from 1,170 forestry surveys in all major forest types in the Amazon. They generated the first basin-wide estimates of the abundance, frequency and spatial distribution of thousands of Amazonian trees. “Because over 120 researchers have pooled their data, we were now able to make a collective analysis and provide a first picture of the whole”, says first author Ter Steege. “Not only do the most common species now have a number, they also have a name. This is very valuable information for improving preservation of Amazonian ecosystems and species”.
A small number of species produce half of the ecosystem services
The lack of basic information about the Amazonian flora on a basin-wide scale has hindered Amazonian science and conservation efforts. “In essence, this means that the largest pool of tropical carbon on Earth has been a black box for ecologists, and conservationists don't know which Amazonian tree species face the most severe threats of extinction”, says Nigel Pitman, Robert O. Bass Visiting Scientist at The Field Museum in Chicago, and co-author on the study.
The study suggests that hyper-dominants – just 1.4 percent of all Amazonian tree species – account for roughly half of all carbon and ecosystem services in the Amazon, such as water, carbon and nutrients. This is important information for governments and conservation organizations.
The World Wide Fund (WWF) call the research “cutting edge”. WWF Netherlands director Johan van de Gronden: "It is the first time that so many data from the entire Amazon are available in one study. A conservation organization such as WWF, can now determine much more accurately which areas hold the richest, most diverse nature, and in which regions potentially endangered species are found. For the future of the Amazon this is of great importance.”
Why is it that just 227 species are so successful? It is a fact that these “hyper-dominant” species, as the authors termed them, are found across large surfaces and in large numbers. They must be able to deal with parasites and fungi very well, because these affect mostly common species. At the same time, almost none of the 227 hyper-dominant species are consistently common across the Amazon. Instead, most dominate a region or forest type, such as swamps or upland forests. Eschweilera coreacea (a species from the Brazil nut family) is the only species dominant in all regions. Why these species are so dominant is still open to debate, the authors say.
Among other possible explanations, the authors suggest that hyper-dominant trees may be common because pre-1492 indigenous groups cultivated them, though this is a topic of debate. “Fact is that several hyper-dominants are of enormous value to local people”, says Tinde van Andel, ethnobotanic at Naturalis Biodiversity Center and one of the co-authors. ”Açai palm (Euterpe oleracea) grows in enormous numbers in Amazonian swamps. Thousands of families in Brazil, Surinam and Guyana make a livelihood harvesting and selling fruits and palm hearts of this species.”
36% of the species are rare and unknown
The study also offers insights into the rarest tree species in the Amazon. According to the mathematical model used in the study, roughly 6,000 tree species in the Amazon have populations of fewer than 1,000 individuals, which automatically qualifies them for inclusion in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The problem, say the authors, is that these species are so rare that scientists may never find them. Ecologist Miles Silman of Wake Forest University, another co-author of the paper, calls the phenomenon “dark biodiversity”, akin to “dark matter” in cosmology. "We know it is important, but it is devilishly hard to detect”, says Silman.
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- Photo 01 Canopy of forest in French Guiana. (c) Daniel Sabatier, permission granted.
- Photo 02 Canopy of forest in French Guiana with Amazonian hyper-dominant tree species, including Symphonia globulifera, Euterpe edulis (small starlike crowns) and Mauritia flexuosa (large fan-shape leaves). (c) Daniel Sabatier, permission granted.
- Photo 04 Forests along the Los Amigos River in southeastern Peru. (c) Antonio Vizcaíno, permission granted.
- Photo 05 The interior of a floodplain forest in southeastern Peru (c) Claire Salisbury, permission granted.
- Photo 06 Mauritia flexuosa, an Amazonian hyper-dominant, along the Rio Negro, the largest black water river in the Amazon basin. Mauritia is an important food source for macaws and locally used for food, roof thatch, and handicrafts (c) Hans ter Steege, permission granted.
- Photo 07 Seasonally flooded forest (igapo) along the Jau River, in Jau National Park (central Amazon), the second largest forest reserve in South America, covering an area greater than 2.2 million hectares. Jau National Park has been declared a UNESCO World Heritage Site (c) Hans ter Steege, permission granted.
- Photo 08 Panorama of Caxiuana River, Pará, Brazil (c) Hans ter Steege, permission granted.
- Photo 09 Morro de Seis Lagos, upper Rio Negro, Brazil. An area with large stretches of white sand and potentially high plant endemism (c) Hans ter Steege, permission granted.
- Photo 10 High water in the low varzea forest along the Solimoes (Amazon) River, here dominated by Cecropia latiloba. The difference between high and low water is over 12m. The high water level can be seen on each of the trees. (c) Hans ter Steege, permission granted.
- Photo 11 Trunk and part of the canopy of a Brazil nut tree (Bertholletia excelsa) in central Amazonia. Brazil nut is one of several hyper-dominant species with a long history of human use. (c) Hans ter Steege, permission granted.
- Photo 12 Canopy of central Amazonian mixed forest, one of the richest tropical forests in the Amazon (c) Hans ter Steege, permission granted.
- Photo 13 Panorama of Rio Negro, the largest black water river in the world, ca. 2200 km long, draining an area of ca. 700,000 km2 (c) Hans ter Steege, permission granted.
- Photo 14 Flowers of the hyper-dominant tree species Gustavia hexapetala in Brownsberg Nature Park, Suriname (c) Hans ter Steege, permission granted.
- Photo 15 Establishing tree plots in remote areas of the Amazon requires lodging in large or smaller camps. This photo shows the base camp used in 2004 to inventory trees in the Lely Mountains of Suriname (c) Hans ter Steege, permission granted.
- Photo 16 Establishing tree plots in remote areas of the Amazon requires lodging in large or smaller camps. This photo shows a forward camp used in 2004 to inventory trees in the Lely Mountains of Suriname. The camp was dubbed Komo-kondre, after the covers of the hammocks, made out of Komo garbage bags (c) Hans ter Steege, permission granted.
- Photo 17 Some hyper-dominant tree species are of great importance to the Amazon people. The fruits of Euterpe oleracea are part of the staple food of the Aucan Maroons of the Marowijne district, Suriname. (c) T. van Andel, permission granted.
- Photo 18 Delta of Amana Lake near Tefe (Amazonas, Brazil) - Varzea meets Igapo. (c) F. Wittmann, permission granted.
- Photo 19 Rio Negro from Inselberg near Sta Isabel. (c) F. Wittmann, permission granted.
- Photo 20 Varzea herbs and forest Mamiraua. Varzeas cover roughly 10% of the Amazon and are flooded for prolonged periods each year. (c) F. Wittmann, permission granted.
- Photo 21 Virola surinamensis fruit - Mamiraua Reserve. This species, member of the Nutmeg family, is one of the hyper-dominant tree species in the Amazon (c) F. Wittmann, permission granted.
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- Hans ter Steege
- Photo 21 Virola surinamensis fruit
- Photo 20 Varzea herbs
- Photo 19 Rio Negro
- Photo 18 Delta of Amana lake
- Photo 17 Harvesting fruits Suriname
- Photo 16 Komo Kondre camp
- Photo 15 Base camp Lely mountains
- Photo 14 Gustavia
- Photo 13 Rio Negro
- Photo 12 Canopy Amazonian forest
- Photo 11 Brazil nut
- Photo 09 Morro de seis lagos
- Panaorama of Caxiuana river
- Photo 07 Jau river
- Photo 06 Mauritia
- Photo 05 Floodplain forest Peru
- Photo 04 Los Amigos
- Photo 02 Canopy of forest French Guiana
- Photo 01 Canopy of forest