Forests in southern Tasmania were found to store more carbon than any other forest studied. Photo: Don Shearman via flickr.
If you're a regular TreeHugger reader you probably know that tropical rainforests suck huge amounts of carbon out of that air, but what you probably don't know is that, according to new research published in the Proceedings of the National Academy of Sciences (brought to my attention by Mongabay), temperate forests probably store even more carbon. Far more in fact than IPCC average figures used in determining the impact of deforestation:Researchers at the Australian National University looked at 100 forest sites around the world and found that temperate moist forests stored an average of 377 tons of carbon per hectare in above ground biomass; subtropical moist forests, 294 tC/ha; cool dry temperate forests, 176 tC/ha; and, tropical rainforests, 171 tC/ha.
Of the sampled sites, the forests with the highest amount of stored carbon per hectare were found to be in Australia: Southern Tasmania, with about 750 tC/ha stored in above ground biomass; and, central Victoria, with slightly under 600 tC/ha.
For comparison, the tropical lowland forests in Borneo and the forest along Oregon's coast stored similar amounts of carbon: Approximately 430 tons per hectare.
Big Differences Between These Stats and IPCC Default Values
The really big deal in all this really has to do with climate change policy -- even though the discovery is pretty interesting unto itself. When calculating the effects of deforestation and forest degradation on the climate, the IPCC uses default values based on forest type.
These stats get the relative positions of carbon stored in forests correct -- cool temperate moist forest being slightly higher than tropical wet forests, followed by warm temperate moist forest. But this new research shows that the average amounts stored vary much more widely than do the IPCC figures, especially when it comes to the temperate forests.
Temperate Forest Store Double the Carbon as Tropical
The IPCC default value for cool temperate forest is about 225 tC/ha for above and below ground storage, but this new research places that figure at over 600 tC/ha. Warm temperate forests showed similar discrepancy: 500 tC/ha versus the IPCC stat of about 275 tC/ha. Cool temperate dry forests and tropical moist forest also showed significant differences.
So why the difference in stats? The researchers say, "Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks."
Long story short, if we're not paying enough attention to preservation of tropical rainforests, we're really not paying enough attention to preservation of temperate forests.
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