Rebecca Vineyard
September 03, 2015 7:32 am

When it comes to the world’s tree population, there’s good news, and there’s bad news.

The good news is, scientists say there are waaaay more trees on the planet than previously believed: there are around 3.04 trillion; the previous estimate was 400 billion. According to The Washington Post, the study also defines the term ‘tree,’ since science is all about precision: it’s called “a woody plant that, at breast height, has a stem that is at least 10 centimeters in diameter.” We think this might allow some pretty lofty (get it?) bushes to eke through, but otherwise, that sounds like a pretty legit definition of a tree.

In a study released in Nature last week, a team of 38 scientists has determined that there are about 422 trees for every person on the planet. They were able to do so by combining two separate methods of sampling trees: satellite observation, and ground based ecological work.

Essentially, satellites tell us where forests do and don’t exist, but they can’t show us the number of trees in a specific area. That’s where the ground-based ecological work comes in: it goes underneath the canopy and can identify how many trees there are in a given area.

Sadly, though, they don’t consider this entirely good news: the researchers estimate that about 15.3 billion trees are lost annually, due to both human and natural causes. While the researchers say that perhaps five billion of those may grow back, that’s still a loss of 10 billion trees per year.

The study also found that there are 46 percent fewer trees on Earth since humans began leveling forests; that’s nearly half. Thomas Crowther, the lead author on the paper and a postdoctoral researcher at the Yale School of Forestry and Environmental Studies calls human involvement in deforestation—which can also be caused by wildfires, pests outbreaks, etc.— an “astronomical thing.”

The research also asserts, “The negative relationships between tree density and anthropogenic land use exemplify how humans contend directly with natural forest ecosystems for space.”

Of course, now that we know there are so many trees, doesn’t all this fuss about deforestation sound a little out of hand? Well, actually, says conservation biologist at the United Nations Foundation Thomas Lovejoy, who wasn’t involved in the research, it isn’t. He says, “It does not say there’s more forest. It just says there’s more trees in the forest.”

Crowther was partially inspired to conduct his research by the Billion Tree Campaign, which was started by the UN Environment Programme in 2006, and has since been taken over by the Plant-for-the-Planet Foundation. Their goal, Crowther explains, is to generate forests globally—yet they lack the baseline information that would show them how many trees they need to plant.

Though his research does show that there are more trees on the planet than previously believed, the rates of deforestation that 46 percent that humanity is responsible for, means many more trees will have to be planted to combat this issue. Luckily, Crowther believes—and so do we—that activists and plant lovers will rise to the challenge.

(Image via iStock)

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