There are some people running around up here claiming the alder isn't a native tree. One of them is even stripping out all the young alders from under a Douglas Fir in a beach area, claiming the alders are sucking all the nitrogen away from the fir, while letting the same ground be taking over by wild rose plants.
Say what? Alders fix nitrogen. They're native. I think the people doing this must be either playing a logging company propaganda game, or else they've misread Vancouver's journals, which state that alders here "resemble" English alders.
Somebody else poisoned all the alders out of a garden stand of man-planted Douglas Firs on the way out of town. Everybody up here says they want to live "in the woods," but then why do so many of them keep trying to make it look like the Seattle arboretum?