Researchers Discover the Tallest Known Tree in the Amazon

Science
جمعه 5 مهر 1398 ساعت 14:12
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Smith sonian mag
Sheer curiosity led Eric Bastos Gorgens and his team to the tallest tree in the Amazon. At 88.5 meters, or over 290 feet, the tree species Dinizia excelsa , or angelim vermelho in Portuguese, beat out the previous record holders by almost 30 meters.
The forest engineering professor and researcher at Brazil’s Federal University of Jequitinhonha and Mucuri Valleys (UFVJM), along with several other researchers from Brazil and the United Kingdom, was examining data from Brazil’s National Institute for Space Research (Inpe) when he noticed something out of the ordinary.
At first it was just a set of numbers on a screen that let the researchers know giants were growing in the Parú State Forest conservation area in the state of Pará. It took time and dedication to figure what the height measurements represented.
“It could have been a bird flying by, a tower, a sensor error,” says Gorgens, the lead author of a recent study about the trees published in the journal Frontiers in Ecology and the Environment . “So we started to look into what could have given us these numbers that were so far from standard. And as we started looking at the data more carefully, we realized they weren’t errors. They were, in fact, giant trees.”
Inpe used satellites to scan 850 random swaths of the Amazon between 2016 and 2018—each measuring 12 kilometers by 300 meters, almost 900 acres—in a project to map remote areas of the rainforest. As Gorgens and his team pored over the data, they soon realized that several of the areas registered during the scans had trees much taller than they had expected to find, and all of them ended up being from the Dinizia excelsa species. And there was, of course, one that stood above the rest.
Most of the giant trees surrounded the Jari River, a northern tributary of the Amazon River that runs along the border between Pará and the neighboring state Amapá in the eastern Amazon, a part of the Guiana Shield.
The team members knew they had to get there to see the angelim vermelho trees for themselves.
After a lot of careful planning, with Inpe’s data pinpointing the exact location of the trees, the researchers headed out on an expedition that would take them over 240 kilometers into the rainforest, up wide rivers and over rocky rapids as they travelled by boat, then cutting their own trail as they finished the journey on foot.
It took five days to arrive at base camp, which allowed the team to easily visit several of the giants, most of which were located on the edge of the river and towered above 70 meters. With just two days to collect samples and take measurements of the trees, they knew they wouldn’t be able to reach the tallest of them all, still another three to four kilometers away according to the satellite data. It would have to wait until next year, when they plan to go back for a longer trek into the rainforest.
“Everything we saw there was new,” Gorgens says. “There was absolutely no record of anything there.”
The tallest tree they were able measure came in at 82 meters, confirmed when Fabiano Moraes, a specialist in tree climbing, used ropes to scale as high as possible before letting a measuring rope drop to the ground.
The researchers aren’t sure what pushed the trees, often used for timber, to such heights. The exact age of the trees has yet to be measured, but the researchers believe they are roughly 400 to 600 years old. The megaflora likely survived so long in part due to their distance from urban and industrial areas, as well as protection from high winds and storms passing through the area which could easily topple the behemoths.
Continued research of the specific area where the angelim vermelho trees are located will lead to a better understanding of the conditions that have allowed them to thrive. But with a normal mortality rate of just one percent per year in their region of the eastern Amazon, trees are already more likely to grow larger than in the western Amazon, which has a two percent tree mortality rate, according to Timothy Baker, an associate professor of tropical forest ecology and conservation at the University of Leeds who was not involved in the new research.
“Such giants are unlikely to be found in western Amazonian forests—in Peru or Colombia, for example—because the natural mortality rates of the forest are much higher," Baker says. “This difference seems to be related to the more frequent storms and less stable soils in western Amazonian forests.”
Even more important than why the mammoth trees are still standing is what they do to facilitate the health of the environment.
“Just one of these trees is capable of storing the same amount of carbon that 500 smaller trees would store in a normal forest,” Gorgens says of the giant angelim vermelho trees. “Each individual is worth almost a hectare of carbon.”
For Baker, the newfound ability to map these giants and study their role in the global carbon cycle is what makes this discovery so significant.
“Results from our existing plot data show that the forests of the Guiana Shield have the highest amounts of carbon stored above the ground of any Amazonian forests,” he says. “There are typically over 200 tons of carbon per hectare in the trees of these forests.”
The Amazon rainforest has long been at risk, with threats of deforestation and contamination caused by illegal mining, logging and farming pushing it to the brink. A recent increase in fires raging through and destroying large chunks of the region has called more attention to the Amazon’s woes, as well as the need to preserve what’s left of it.
“If not significantly disturbed by humans, the forests of this region can be particularly carbon-rich,” Baker says. “And that is an important argument for their conservation.”
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