New research suggests there are seven and a half times more trees on Earth than was previously believed.
In the past, researchers believed there were only about 400 billion trees on Earth, which works out to about 61 per person; this new estimate of 3.04 trillion trees is about 422 trees per person, Yale University reported. Despite these findings, the scientists believe the planet has lost about 46 percent of its trees since the dawn of human civilization.
To make their findings, the researchers used a combination of "satellite imagery, forest inventories, and supercomputer technologies." The results offer what has been dubbed the most comprehensive assessment of tree populations in history.
"Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution," said Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the study. "They store huge amounts of carbon, are essential for the cycling of nutrients, for water and air quality, and for countless human services. Yet you ask people to estimate, within an order of magnitude, how many trees there are and they don't know where to begin. I don't know what I would have guessed, but I was certainly surprised to find that we were talking about trillions."
The highest densities of trees were found in the boreal forests in the sub-arctic regions of Russia, Scandinavia and North America, but the tropics is the largest forest area and is home to 43 percent of the world's trees. The findings demonstrated how tree density can change within forest type in response to specific factors. Human activity is the primary driver of tree loss across the globe, and the recent study pointed out how historical land use decisions have had a major impact on natural ecosystems.
"We've nearly halved the number of trees on the planet, and we've seen the impacts on climate and human health as a result," Crowther said. "This study highlights how much more effort is needed if we are to restore healthy forests worldwide."
The findings were published in a recent edition of the journal Nature.
