Planet Earth is losing 15bn trees a year, and replacing only 5bn of them, according to a new study by a team at the Yale School of Forestry and Environmental Studies.
It is an undisputed fact that trees are the world’s single largest source of breathable oxygen. But, the world has lost 80% of our original forests in the last decade, as revealed by the United Nations Environment Programme (UNEP). This is very alarming.
As conveyed in very simple terms by, trees promote life. Not only do trees produce oxygen and sequester carbon dioxide, they also provide homes for animals, recharge groundwater, replace soil nitrates, prevent erosion and more. The addition of an indigenous tree to any environment will have countless environmental benefits.
The study, published in the acclaimed journal Nature, estimates there are somewhere around 3.04tn  trees on the planet, which is about 400 trees for every person.
Though this may seem a lot, but we have to understand that the Earth was home to nearly twice as many trees, before humans began clearing forests.
The number of trees cut down is almost 3tn since the start of the human civilisation, according to the study leader Thomas Crowther, a postdoctoral fellow.
The authors of the study has defined “tree” as a plant with a woody stem that is at least 10cm wide at chest height. Instead of relying only on satellite imagery to estimate the number of trees, as done in some earlier studies, the team also relied on 429,775 ground-based measurements of tree density, mostly from national forest inventories.
Crowther and his colleagues reported that more than 40% of the trees on the planet (1.39tn ) are located in tropical and subtropical forests.
The next largest chunk, 24.2%, can be found in the boreal and tundra zones of Canada, Russia and northern China.
The remaining tree population, 21.8%, can be found in more temperate parts of the world, including the US and Europe. In order to determine how many trees used to be on the planet, the researchers overlaid their new map of tree density on top of the UNEP prediction of where forests used to be based on the climate conditions of the pre-Pleistocene period. The Pleistocene Epoch is typically defined by as the time period that began about 1.8mn years ago and lasted until about 11,700 years ago.
The net loss in the number of trees, according to the  study, is about a third of a per cent of all trees globally. One of the most dominant themes of the research is how large an effect humans are having on the tree population on the planet.
To quote Crowther, human activity came out as the strongest control on tree density across all biomes. So, what is the solution? We, humans, have a responsibility to overwhelmingly compensate the planet by planting more trees and not cutting down them as before.

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