Brazil celebrates its giant trees on Earth Day 2023

Imperial Palms form an avenue in Rio's botanical garden and organisers are hoping, by establishing their own trail of giant trees, it will help to promote awareness of their environment.

These trees - and the animals which rely on them - are threatened and botanists are keen that everyone joins in the effort to preserve the country’s unique forests, inside and outside the Amazon.

Botanists calculating the carbon content of the garden studied 4633 trees, bushes and palm trees and discovered where the tallest were. To catalogue the volume of the trees, the botanists used lidar technology which stands for ‘light detecting and ranging’.

It is used by the National Oceanic and Atmospheric Administration in the US and is a combined laser, scanner and GPS receiver which generates accurate 3D information.

Marcus Nadruz is one of the botanists at Rio de Janeiro Botanical Garden explains how computer-aided mapping can help measure the trees.

"Depending on the colour, the more yellow, the higher is the tree. You can see the yellow colour much more intensely here, which is precisely the location of the highest tree in the botanical garden, measuring almost fifty metres."

The garden was originally created in 1808 to acclimatise plant species from other continents. At the time Brazil was searching for new crops to boost the economy after gold production had been depleted.

Another botanist, Rafaella Forzza, works regularly in the Amazon where she became familiar with Brazil's recently discovered largest tree, the red angelim or Dinizia excelsa.

The largest tree measuring 88 metres was first discovered 4 years ago using lidar and it was only reached by land last September 2022. 

"Once you reach the foot of the tree, it is hard to see, because the canopy of the forest obstructs the top of the tree, you cannot see," she explains.

"The branches of the angelim or the sumauma begin to branch out above the normal canopy of the forest." The grand imperial palms are the second highest trees in the garden. One original palm tree has reached 48.1 metres in height.

The garden is also home to a Tasmanian eucalyptus, known commonly as a blue gum which is 39.5 metres tall. It can reach up to 45 metres in its natural habitat.

Many of these trees are threatened, the samauma is used to make plywood and the angelim is Brazil's most exported tree.

With Earth Day 2023 falling on April 22nd the botanists are hoping these giants will not go unnoticed.