"Matalog" schreef
I understand that when sunlight is around trees and plants will give off
oxygen and soak up carbon dioxide (photosynthesis) - but at night is it true
that they will give off carbon dioxide? If so, how much of each will be
released during the night and day.

***
That is fairly simple. Take the tree or plant when it dies, add all the
material (leaves, fruits, seeds, etc) that it shed over its lifetime, burn
all this and measure the resultant CO2. Divide this by the lifetime of the
tree or plant. This will give the average net take up of CO2. Take it from
there.
PvR