The largest tree in the Amazon has a crown of about 60 meters wide. Say: five city buses in a row, or two oversized blue whales – themselves record holders as the largest animals on earth. This makes the diameter of the tree at least 5 meters larger than that of its forest companions, according to Fabien Wagner, the tropical forest biologist who discovered the tree.
Appointing a champion in the largest rainforest on earth, with an estimated 400 billion trees, seems unlikely. But Wagner, who after an earlier career at NASA’s Jet Propulsion Laboratory, started the start-up CTrees to become CO2 developed a model to better map the Amazon canopy. The tallest and most leafy trees can produce a lot of CO2 store, so if you know where they grow you can protect them better.
Extensive tree crowns
Wagner was to give a presentation at an important scientific conference in early December, and in preparation he decided to use his model to search satellite images for extensive tree crowns. Initially he only looked for trees with a crown of 50 to 55 meters wide – to his knowledge the largest achievable size.
But statistically speaking, there might be an outlier, he reasoned. And so he broadened the search until he found the 60-meter tree. To see whether his model was really reliable, he looked up the tree in question in higher resolution on Google Earth Pro, and using a digital ruler arrived at a diameter of almost 62 meters.
Growth strategies
Based on his model, he estimates the height of the tree at about 50 meters. So a small one, knowing that trees in the Amazon can sometimes grow more than 80 meters high. But large trunks do not necessarily lead to large crowns, Wagner emphasizes on the CTrees website. There appear to be two growth strategies, both of which lead to a top biomass (roots, trunk, branches and leaves added together): either shooting up or fanning out with the tree crown. Which of the two groups – the tall trunks or the broad crowns – has the highest biomass still needs to be investigated further, says Wagner.
He does have a suspicion to which tree species the 60-meter-wide champion crown belongs: Bertholletia excelsathe species on which the edible Brazil nut also grows. Another contender is the Parkia pendula or the kwatakama, a fast-growing tropical species whose wood is used, among other things, for floors and railway sleepers.
The exact coordinates of the tree have not yet been released. After all, it is not only useful for nature conservationists to know where the largest and bulkiest trees are, but also for illegal loggers.