Forests cover approximately one third of the world’s terrestrial land surface. A recent study led by Yale University has determined the number of trees left on Planet Earth with an accuracy of 95% and reveals the figure is eight times as many as previously thought.
The study, led by Yale University, was conducted by an international team of researchers and has provided the most accurate count yet for the number of trees on Earth. The study was published in the journal Nature, and reveals that there are 3.04 trillion trees remaining on the planet. An eligible “tree” is defined as “a plant with woody stems larger than ten centimetres diameter at breast height.” Previous studies only counted trees more than 50 centimetres. This may go some way to explaining why the current estimate is eight times as many as previously thought.
The tree count was made using satellite imagery and more than 400,000 ground measurements and is claimed to be 95% accurate. The report suggests that the number of trees has plummeted 46% since the dawn of human civilization 11,000 years ago. It is estimated that the figure once stood at more than six trillion. The findings are hoped to help map endangered species, show how water is recycled and reveal how much carbon dioxide is being absorbed from the atmosphere.
Lead author Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies said: “Perhaps most significantly, the study highlights the dramatic effect humanity is having on the natural world. 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. This study highlights how much more effort is needed if we are to restore healthy forests worldwide”.
1.39 trillion trees grow in tropical and subtropical forests; 0.74 trillion grow in boreal regions and 0.61 trillion in temperate regions. Thanks to the information collected by the ground station researchers, it was possible to measure the density of trees in forests around the world to come up with accurate figures. The study found that there was a gross loss of more than 15 billion trees a year and a net loss of 10 billion when regrowth was taken into account. There are currently 422 trees per person in the world but, if current trends continue, that will fall to 214 in 150 years.
Data from the study could be useful in working out how much carbon is stored in terrestrial vegetation. “In the study, we show that there is a positive relationship between the amount of trees in an area and the amount of carbon storage,” Crowther told IFL Science. However, he noted: “This relationship was not strong because the highest densities of trees are often dominated by a large number of small trees that don’t store much carbon.”