I
wish everyone could enjoy the beauty of trees as much as I do. Each one is a better
poem than anything written by a human. Even ugly trees (and there are a few)
are interesting. But if someone just thinks trees are useful, I’ll settle for
that.

I
had my botany students do an exercise in trigonometry, in which they measured a
tree (each group had its own tree) and estimate the number of twigs on the
tree. The results were astonishing. It is not unusual for a big oak tree to
have 50,000 twigs.

Then
I had them estimate their own carbon footprints, using websites that do the
calculations. A typical number would be 50,000 kg of carbon dioxide per year
from their activities.

Next
I had them do some simple arithmetic. Just some multiplying and dividing. I had
them assume (from actual measurements made in previous years) that each twig had
100 square cm of leaf area. This would mean a typical tree had 5,000,000 square
cm of leaf area, which is 500 square m (they had trouble with this). If you
assume (also based on measurements in previous years) that a typical tree
absorbed 10 grams per square meter per day of carbon dioxide, this would be 5,000
grams or 5 kg of carbon dioxide per day. This may seem low to you, but remember
these are post oaks in a dry forest. This means that it would take their tree
10,000 days to absorb 50,000 kg of carbon dioxide. Assume a growing season is
180 days. It would take the tree over 55 years to absorb that much carbon
dioxide.

Which
means there has to be 55 mature oak trees to compensate for one person’s carbon
emissions.

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