Earth’s Second Lung Has Emphysema
Many consider forests as the ‘lungs’ of the planet — the idea that trees and other plants take up carbon and produce oxygen (the carbon and oxygen cycles). If we are to be fair though, the oceans store about 93% of the Earth’s carbon pool (excluding the lithosphere and fossil fuels) and oceanic phytoplankton produces between 50 and 80% of the oxygen in the atmosphere. For comparison, the terrestrial biosphere — including forests — stores only about 5% of the Earth’s carbon and produces most of the remainder of atmospheric oxygen.
So, there’s no denying that the biggest player in these cycles is the ocean, but that’s not the topic of today’s post. Instead, I’m going to focus on the terrestrial biosphere and in particular, the carbon storage and flux of forests.
Now it’s pretty well established that tropical forests are major players in the terrestrial carbon cycle, with the most accepted estimates of about 55% the terrestrial carbon stock stored therein. The extensive boreal forest, covering most of the northern half of North America, most of Scandinavia and a huge chunk of Russia, comes in globally at about 33%, and temperate forests store most of the remainder.
That is, until now.
A niggly issue with estimating global carbon stocks in forests is that quite a bit of it is stored underground. In tropical forests at least (not including the few peatland forests), most (> 50%) of the carbon resides in the living biomass above the soil; however, in boreal forests where peatlands are extensive, 95% of the carbon is found below ground in the peat and soils. While most of this subsurface carbon is found in the top layers of the soil and peat, if you don’t dig down deep enough, you might miss an important component of the total carbon stock.
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