Awhile back, I was caught off guard when a roomful of lecture attendees scoffed at my rejection of the idea that forests breathe. I hadn’t thought very deeply about it. But it seemed (still seems) like a sloppy metaphor rather than something anyone would seriously defend, which they did. But I found this definition useful:
Any of the various analogous processes by which there is an exchange of gases.
So, as an analogy, I can live with it. Sure, gasses are exchanged by a forest differently than, say, by a grassland or by the ocean. But in order to take the analogy seriously, i.e. use it to think, I’d need something more similar to a single organism than a forest. For example, an aspen colony or even a slime mold or biofilm. But a forest is just too much of a collective of organisms for me to really think of it as a single organism.
I mean no disrespect to the Big Thinkers out there who rely on analogical subsumption in order to think bigger thoughts. I do it myself all the time. But we need to be honest about our (purposeful) sloppiness when doing so.