Study counts 3 trillion trees on Earth; but falling on an alarming rate

More than 3 trillion trees now grow on Earth, seven times more than scientists previously thought. But it’s also trillions fewer than there used to be, a new study concludes.

A United Nations-affiliated youth group had a goal of planting one billion trees and Yale forestry researcher Thomas Crowther was asked if planting that many trees would do anything to help combat human-made climate change. Trees capture and store heat-trapping carbon dioxide.

Crowther said first he had to figure out how many trees are on Earth and that number was far more than anyone expected: 3.04 trillion trees, according to a study published Wednesday in the journal Nature.

The previous estimate was 400 billion trees and that rough count was based on satellite images peering down from space. Crowther and colleagues used 429,775 ground-based measurements along with satellite measurements and computer models to get a more accurate figure.

Nearly 1.4 trillion of Earth’s trees are in tropical and subtropical forests, but that’s also where the rate of forest loss is the highest, the study found.

Outside scientists such as Norm Christensen of Duke University said the way the study was conducted made sense and is well executed. But he wonders how useful it is to know the number of trees. Former U.S. Forest Service chief Mike Dombeck said the same thing, adding the issue is more than a number but the big picture of what trees do to help Earth and local ecosystems.

Crowther said he and his colleagues all wondered the same thing, but the detailed maps of forest density can help conservation efforts. For example, if a jaguar needs a certain number of trees to survive, this can help in rebuilding the right habitat for the large cat, Crowther said.

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Source:Timesofindia

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