Do you know the old joke about the fellow who was looking for his keys under a streetlight? A neighbourly passerby came up and offered to help. “Did you lose your keys here?” he asked. “No,” the fellow replied, “over there in that alleyway – but the light’s better here”.
This is quite funny until you realize that as ecologists, we do it all the time.
Last month I was in the Gaspesie region of Quebec, where I have a field research project on carbon storage in soils of spruce budworm-impacted forests. We have a set of 13 watersheds –some with spruce budworm control programs, and some without. At sites in each watershed we collect falling budworm frass (that’s what the hula-hoop in the right-hand photo is for), sample soil nutrients and carbon, and a bunch of other things. Actually, the particular things we’re sampling don’t matter to my point today; instead, what’s relevant is that we have a set of sampling points about 50 m apart at each site, and we need to visit each sampling point repeatedly over the season.
At some of our sites, like that in the left-hand photo above, these visits are a stroll in the park. The trees are widely spaced, the forest floor is a soft, springy carpet of mosses, and sight lines are good – you can find one trap easily from the last. Other sites are like the one on the right: a dense tangle of small dead trees that tear at your clothing, trip you when you aren’t looking (or even when you are), and screen your view so that a colleague ten metres away is invisible.* The difference: the left-hand site has been “precommercially thinned”, with small trees removed so the remaining ones could grow more quickly to harvestable size. The right-hand one hasn’t been. Both kinds of stands are common in the region’s forests.
I was walking with a collaborator through the stand in the right-hand photo, and after snagging myself painfully on the third branch in a few minutes, I said with a dramatic sigh, “remind me again why we picked this darned site?”** To which my collaborator replied “You picked this one, Steve, and I told you it would be like this”. OK, I was busted… like many of the struggles I find myself in, this was entirely my own fault.
But here’s the thing: it would have made our lives easier not to pick the right-hand site. But if we hadn’t picked it, we wouldn’t have been able to learn anything about that kind of forest. We’d know a lot about the walk-in-the-park thinned stands, but nothing about the dense-tangle unthinned ones. We’d be looking for our keys under the streetlight – but what if they’re really in the alleyway? Surely we should be studying the forest as it is, not the forest as we wish it were.
This would be a trivial realization, I admit, if it were only about my thinned vs. tangly forest plots. I think our research is pretty interesting, but I’m not going to claim it’s either the foundation or the pinnacle of all ecological science. But it isn’t only about my tangly plots. We look for our keys under the streetlight all the time. What do you think accounts for the enormous volume of ecological science done in the rocky intertidal zone, and the relative paucity of work in salt marshes, mudflats, and kelp forests? Convenience. Why do you think we know an enormous amount about the benthic invertebrates of shallow, cobble-bottomed stream riffles, but little about deep rivers or mud-bottomed streams?*** Convenience again. I bet you have your own favourite example; please leave it in the Replies.
Sometimes the keys really are under the streetlight, of course (cue discussion of model systems, and that’s an argument I’ve used many times). But unless we look elsewhere, we’re going to leave a lot of keys unfound.
© Stephen Heard August 16, 2022
Oh, look, there’s a relevant xkcd! There’s always a relevant xkcd.
Image: two forest plots. Own work, CC BY 4.0.
*^I finally understand why kids play “Marco Polo” in swimming pools! They’re in training to become forest ecologists. It’s remarkable how well shouts of “Marco!” and replies of “Polo!” get team members together in the field.
**^It’s possible that I didn’t say “darned”.
***^Lest you think I’m a bit quick to criticize fields other than my own: I’ve done stream ecology. (For example, this and this.) And just like everyone else doing stream ecology, I worked under the streetlight in easily waded, easily sampled shallow, cobble-bottom riffles.