[ryanmercer]

>What about nitrogen?

There are several trees are nitrogen fixing species, they're a pretty important part of permaculture. Some of the mycorrhizal networks that exist in many forests also fix nitrogen. Also, some species like pine trees get a lot of their nitrogen from endophytes living in their tissue.

[contravariant]

Unfortunately the nitrogen fixing species mostly absorb N2. Which I'm fairly sure isn't the compound that OP wanted removed from the atmosphere. They were probably thinking about nitrogen oxides.