GardenDrumExactly where are the world’s 3 trillion trees?

Shade treeDid you know that the world has 3.04 TRILLION trees? That’s 422 trees for every person living on earth today. But it’s not just the total number that’s fascinating, but where they all are…and what happened to that other 3 trillion that used to be around before we were.

Published in Nature in September, the research team led by Thomas Crowther of the Yale School of Forestry and Environmental Studies combined two sampling methods of satellite data and ecological work on the ground, and defined a ‘tree’ as a plant with a stem at least 10cm (4 inches) diameter at chest height.

The sobering corollary to the estimate is that every year we are LOSING 15.3 BILLION trees through chopping them down, wildfire, pests and diseases. Although about 5 billion are planted or regrow, that’s still a year-in-year-out net loss of 10 billion trees every year, estimated at about half the trees that existed on earth at the beginning of the anthropocene (man-dominated era).

Regrowth forest in north-east USA

Regrowth forest in north-east USA

But exactly where are these trees we do still have? On a straight numbers by country basis, the Top 8 league table looks like this:

Totals in billions
Russia 642
Canada 318
Brazil 302
USA 228
China 140
Democratic Republic of the Congo 101
Indonesia 81
Australia 77

But what about tree density ie trees per square kilometre? Then Finland jumps to the front with 73,000 tree/square kilometre, with Sweden and Slovenia close behind. Not surprisingly, desert areas rank the lowest at less than 10K such as UAE, but Australia has also slipped into that same category (9.9K), along with Namibia, Uruguay, Kazakhstan and all of northern Africa.

Surprisingly, although there is more total forest area in the tropics, temperate regions at higher latitudes have more dense forests.

Researchers comment that:

“in northern latitudes, limited temperature and moisture lead to the establishment of stress-tolerant coniferous tree species that can reach the highest densities on Earth”

Previous research had also suggested that wealthier countries have more trees while poorer countries must sacrifice forest area for food production but this new research did not find a correlation with national GDP.

So where to next with this research? The key to increasing the earth’s tree populations – and with it carbon sequestration, cooling, filtering of water and also air pollution plus well-documented psychological and sociological benefits – is to use this data to calculate how many trees each country can sustain, based on environmental and climate factors, compared to what it now has. This could provide a ‘forest potential’ for each country and a realistic target for which it can aim.

Read more at Nature.com

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One thought on “Exactly where are the world’s 3 trillion trees?

  1. Shame on us Australia. There’s no time to waste. Time we started rectifying the damage we’ve managed to accomplish in the short 200+ years since European settlement.

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