Why does the lowest carbon dioxide concentration occur closest to the forest ?

The forest is highly populated with plants.

Explanation:

The reason the carbon dioxide is lowest near a forest is due to the vegetation. Plants absorb carbon dioxide and produce oxygen, making the carbon emissions low. Unlike a busy city, for example, which would have very high carbon emissions due to the lack of plants and increased carbon dioxide output.

Hope this helps,

Panna

its temperature is increasing. this causes molecular vibrations to increase.