The Balance of Nature

Chris Clarke in Pharyngula:

ScreenHunter_21 Oct. 09 09.42One of the things that bugs me most about some of my fellow environmentalists, aside from the patchouli, is the near-religious adherence — even among those enviros who eschew religion — to the notion that natural ecological systems have an innate and emergent self-repairing property. It’s a dangerous idea that breeds complacency, and it’s really widespread.

I’m painting with abroad brush here, I know. I’ll continue to do so for convenience’s sake, but it’s true that a number of enviro types have dropped the notion of a “balance of nature.” In my experience, wildlife biologists and people who study aridland ecosystems are especially likely to have deprecated the Gaia idea of Earth being an overarching, self-regulating system. And paleontologists.

It’s easy to understand how the notion might have come about. Ecosystems get more diverse over time, with the species in them evolving as many ways of making a living as can fit in the space available, and so disruption of an ecosystem might merely open up opportunities for organisms to grow and reproduce. Those disruptions might be truly cyclical, as with tides flooding and draining a tidepool twice a day or freezing temperatures descending on half a continent for four months every year, or they might be cyclical in the stochastic sense — forest fires, 500-year floods and droughts, the occasional exotic pathogen making its way to a new continent. If you stand back and squint, those cycles can look like stability as organisms are killed off and new ones grow to replace them. Especially if you don’t pay attention to the fact that, say, the regrown forest no longer includes American chestnuts.

More here.