An international group of scientists, including researchers, taxonomists and students based at 88 institutions and The Field Museum in Chicago, offer insight into the diversity of tree species within the Amazon rainforest. Launching a large-scale investigation, the team established that an astonishing 16,000 species of trees existed within the Amazon, with over half of all trees belonging to just 277 different species.
The study was published in the Oct. 17 issue of the journal Science.
Amazon Rainforest an Ecological “Black Box”
Studying the Amazon rainforest has presented enormous difficulties in the past. The terrain of the Amazon Basin is often dangerous to navigate, sprawling with exotic vegetation and wildlife, with investigations fraught by uneven terrain throughout many parts of Brazil, Colombia and Peru. Likewise, the Guiana Shield, a Precambrian geological structure, which developed prior to the rapid evolutionary diversification of life on Earth, bears rocky topography.
Scientific knowledge of the Amazonian rainforest has been relatively sparse due, in part, to the afore-mentioned factors, with little known about the breathtaking diversity of the flora across the Amazon Basin.
Nigel Pitman, co-author of the study and employee of The Field Museum, argues this limited information to have been a hindrance to noble conservation endeavors. During a recent press release, Pitman claims “… the largest pool of tropical carbon on Earth has been a black box for ecologists,” before moving on to discuss how conservationists previously had absolutely no clue which species of Amazonian tree faced extinction.
With the latest study, however, the gaps in our knowledge are starting to be filled. In excess of 100 specialists served up extensive data from over 1,000 forestry surveys, representing knowledge from across all forestry types. Scientists catalogued trees with a stem thickness greater than 3.9 inches from these surveys, and approximated the number, frequency and distributions of thousands of trees, yielding an accurate interpretation of the tree population within the Amazon basin.
Hyperdominant Tree Species
After making a series of extrapolations from the accumulated data, which spanned a period of 10 years and covered much of the Amazon Basin and Guiana Shield, the team estimated there to be around 390 billion trees; these included açaí berry and Brazil nut trees.
Hans ter Steege, one of the study’s authors, and researcher from the Naturalis Biodiversity Center in South Holland, states there to be roughly 16,000 tree species throughout the
Amazon, with half of all trees belonging to as few as 227 of these species (1.4% of all species); he maintains this number to be much lower than expected. Steege goes on to discuss the implications of this startling find:
“Thus, the most common species of trees in the Amazon now not only have a number, they also have a name. This is very valuable information for further research and policymaking.”
The largest proportion of trees, falling within this 227 species majority, have been coined hyperdominants by the research group. Intriguingly, these hyperdominants are not “consistently common” throughout the Amazon, adapting to occupy unique habitats and forest types, including swamplands, as well as upland and white-sand forests.
The most common species of the Amazonia is Euterpe precatoria, a slender palm that produces cultivatable berry fruits. Researchers estimate Euterpe precatoria to have an approximate population size of 5.2 billion within the Amazon rainforest.
Threatened Amazonian Tree Species
The authors also used complex mathematical models to estimate the number of tree species that might be endangered. Based upon these predictions, they believe there to be around 6,000 species with populations of fewer than 1,000. These species would, therefore, immediately fall under the Red Data List, as defined by the International Union for the Conservation of Nature.
Alas, the next hurdle lies in actually locating these endangered species of trees. With almost 400 billion individual trees spanning an area that exceeds two million square miles, attempting to find species that have populations of less than 1,000 is an almost insurmountable task.
Miles Silman, an ecologist working at the Wake Forest University dubs this problem “dark biodiversity.” Comparing their predicament to physicists’ models on dark matter, which is theorized to account for much of the mass in the universe, he suggests ecologists face similar issues with their models. Silman maintains that these many endangered species, which have low population numbers, actually account for “… much of the planet’s diversity.”
The implications of the study were briefly discussed by Steege, talking to OurAmazingPlanet. He claims, off the back of their extensive results, researchers can better predict the influence of deforestation and enact new initiatives to spare at-risk species facing extinction.
Meanwhile, the debate rages on as to why some species of trees are hyperdominant, and others are not. Pitman states there to be two trains of thought on the issue; some researchers believe hyperdominant species are more ubiquitous because indigenous people consistently farmed them before 1500, whilst others conjecture hyperdominants to have existed prior to human intervention.
With greater knowledge of these 16,000 reported species of trees, scientists now believe they hold the key to better understanding the Amazon rainforest and more effectively enhancing conservation efforts.
By: James Fenner