The Warming Bog

Using plant time machines to see the future

The dozen open-top domes scattered around the landscape just south of the Calvert Island field station look like moon colonies sheltering the plants inside. That isn’t far from the truth: the clear polycarbonate chambers keep the temperature a balmy 0.7-1°C warmer than the surrounding air during the growing season.

But if we’re talking sci-fi, it’s less a space station than a low-tech one-way time machine for plants.

“It simulates conditions a decade into the future,” explains Andrew Trant, the Hakai Postdoctoral Research fellow conducting the experiment.

The experiment, conducted in two different sites on Calvert Island, allows Trant to look at how plant communities will respond to predicted changes in the climate over the coming years. At the start of the growing season, Trant and five research assistants spent days in the field measuring each plant species and the height of those plants in order to compare their growth inside the warm plots to that in the ambient air.

“With higher temperatures, you get more decomposition,” says Trant. “So there could be a surge in nutrients in the soil.”

Extra nutrients can lead to more growth for some – but not all – plant species.

Take sweet gale, for example. As a nitrogen fixer, sweet gale (Myrica gale) does well in nutrient-poor soils, so a big pulse of nutrients from decomposing matter might actually lead other plants with different growth strategies to outcompete it. That’s just one way that the slightly higher temperatures that are expected to become the norm can quickly alter plant community structure and biodiversity.

That’s why understanding these dynamics now is important. The bog ecosystem is a complicated community already, even though it may not look that way at first glance.

“Walking through [the bog] it doesn’t look like much,” says Trant. “When you actually stop and put your face in the dirt, though, we’ve recorded about 70 species of plants here.”

The technique is adapted from similar Arctic research that showed an increase in shrubs and a decrease in lichens and mosses when researchers warmed plots like Trant’s. More low shrubs trap more warm air; so, essentially, the experiments predict that a warmer Arctic will produce the type of vegetation that will further warm that environment.

“I think you would expect something similar,” says Trant, pointing out however that the bog forest landscape may look similar to the tundra but is in fact quite different.

“The Arctic is going from a treeless tundra to one with more vegetation, whereas we’re in a fairly forested landscape. It’s not going to be as strong a driver as in Arctic systems but it’s the same effect.”