In my problem there is an average net ecosystem production rate of:

0.25 kg°C/m2/yr

Am asked:

a. What percentage of 140,000 tons/yr would be offset from reforesting 45,000 acres?

b. With that what area of reforestation/afforestation would need to be offset by 10% by the same emissions?

How I solved (not sure if correct):

Since 45,000 is in acres I converted to square meters:

45,000 Acres = 182,108,539.008 m2

Then I could say for every 0.25 there would be one m2 from the above number. Therefore I multiplied.

0.25*182,108,539.008 = 45,527,134.752 kg °C

So now I need to convert kg to ton:

45,527,134.752 kg = 50,185.08 tons

So now I just need to divide into 140,000 to find how much it knocks off of the total carbon emitted:

140,000 / 50,185.08 = 2.8%

Is this right? I'd imagine for 10% I'd just have to adjust the acreage to get it just right. With land area being 25,414,258,332.672 m2


1 Answer 1


What kind of forest, 45,000 acres of What? If it's boreal forest it's a slow carbon sink If its tropical, it'll be faster

Forests are largely carbon neutral in terms of carbon emissions. In temperate forests they emit carbon when they go inert for the season.Trees are roughly 50% carbon (dry weight) by mass. Increases in standing timber are directly correlated with increases in bound carbon. But once those trees die they decompose to anerobic co2 again. To grow a pound of wood, a tree uses 1.47 pounds of carbon dioxide and gives off 1.07 pounds of oxygen. An acre of trees might grow 4,000 pounds of wood in a year, using 5,880 pounds of carbon dioxide and giving off 4,280 pounds of oxygen in the process. However deciduous temperate forests put out co2. Tree's with Long life spans and ideal growing conditions are however better carbon sinks, as they accumulate cellulose they sequester carbon. Once they're mature they slow down and become carbon neutral. Trees that largely never stop growing are good carbon sinks

douglas fir
Lawson cypress

Tall Tropical specimens

Bertholletia (Brazil Nut)
  • $\begingroup$ I definitely remember drawing the ire of my teachers by challenging the oversimplified assumptions in problems we were presented! Anyway, If this is a homework problem, I guess the simplifying assumption is that whatever forest it is, it absorbs exactly the amount of carbon the other land produces. So, it just becomes a math problem. $\endgroup$
    – Spencer
    Oct 30, 2020 at 13:06
  • $\begingroup$ Your first answer was deleted because it didn't answer the question. How does this answer the question, which is eventually an arithmetic check? $\endgroup$
    – Fred
    Oct 23, 2021 at 17:07

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