Is Lodgepole Pine Really a Nitrogen Fixing Plant?

Alder is a nitrogen fixing plant. If you take the alder out of this ecosystem, what I found is that eventually the lodgepole pine also declines. And so there's this cooperation going on between these two plant species that is actually making the ecosystem emerge into a more productive place. So then the forest, it's not just adding alder and pine in a pie and saying, if I take away more alder, I'll have more pine,. It's actually that the pie grows when you have the two of them together.