[permaculture] Trees & Co2
toby at patternliteracy.com
Thu Oct 20 12:37:08 EDT 2005
> Apparently a
> hectare of trees only sequesters about 3 tons of carbon per year ?!?!
> Is that true ? Anyone have any other info on this ?
I just did some "back of the envelope" calculations, and that sounds right.
But also, remember that those figures don't include soil flora and fauna,
which can mass as much as the forest, so the numbers could be much higher.
Below is a quote from
"On Monitoring and Measuring Wood Carbon." A cubic meter is 35 cu ft, and a
hectare is about 2.5 acres.
"A reasonable rule-of-thumb is that, for every cubic foot of merchantable
wood in a forest, the forest will contain about 30 pounds of carbon per
acre. Thus, a forest growing at the rate of 70 cubic feet of merchantable
wood per acre per year is increasing its woody carbon stock by around 2100
pounds, or about 1 tonne of C per acre per year.
This estimate is obtained as follows: Different species of wood will vary in
their weight per cubic foot (Table 2). If we assume a dry weight bulk
density of 0.50, each cubic foot of wood would have a dry weight of 31.2
pounds. (Weight of a cubic foot of water times 0.5). Since the merchantable
wood is usually only about 1/2 of the total tree wood (including branches,
stump, large roots, etc.), each cubic foot of merchantable wood represents
around 62 pounds of total tree weight. Since wood is about 1/2 carbon by
weight, there are around 31 pounds of carbon per cubic foot of merchantable
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