Does It Matter Whether The Emerald City's Actually Emerald?

Yesterday the Cascadia Scorecard blog commented on a P-I article from two days ago on the subject of Seattle's troubled urban forests. The article from the Post Intelligencer is quality stuff and you should copy the link for yourself for reading at another time. We know that stuff piles up and you eventually just end up deleting it all because who has time to read that many links, but at least you'll have made an effort. It's about invasive species outcompeting our native floura, a subject also well covered in the David Williams book.

Eric de Place at Cascadia Scorecard wonders if our urban settings are really worthy of our environmental dollar in situations like this:

Folks at the Seattle Urban Nature Project, along with scores of other groups, are in the frontlines of the battle against the aliens. Without their dedication, the city's forests and parks would likely succumb to the greedy monoculture of ivy and blackberry that is already in evidence nearly everywhere. So as a nature-loving city-dweller I'm happy about the much-needed efforts to restore the ecology closest to us.

But the more I read, the more the series also raised some interesting questions--for me, anyway--about how we treat conservation priorities. How do we sort out competing environmental goods, such as increasing urban density and preserving an urban forest canopy? Is urban ecology really the best use of our resources?

And his conclusion is that, actually, it is a good buy. We're not sure we're convinced. He does admit that a lot of the gain from urban environment projects are anthropocentric ("urbanite feel good gardens" we've said previously) and does mention that healthy trees have positive effects on worker morale and retail, but the part of his argument that we're most concerned with:

Even if urban ecological restoration is not the best non-human biodiversity investment available, it still winds up being a plus in nature's scales. Native bird, fish, and plant diversity all flourish when we remove invasive species.

That could use a little fleshing out to our mind. We don't think that walling all of humanity into giant concrete megalopolii where nature is ignored on the inside and encouraged on the outside is really the answer (maybe because City Earth will eventually take over the planet), but we're still a little sketchy on how spending thousands of dollars and hundreds of volunteer hours to clear away blackberries really has an impact.

A commentor to the Cascadia Scorecard post has an answer: We've placed our cities in areas that are particularly environmentally sensitive and there is no wall that we can build to adequately protect nature from ourselves.

Every Salmon that wants to go to the Cedar River has to pass through the Ballard locks, Lake Union and Lake Washington. Every Salmon that wants to go to the Green River has to pass through the Duwamish River...feeding on PCB-contaminated critters. It's all connected. We need to put equal attention on the upper, wild reaches of the watersheds, as well as the urbanized industrial areas.