On a brisk Saturday morning at Bradbury Mountain State Park in Pownal, Maine, Park Ranger Jeff Pengel leads a nature walk he鈥檚 titled 鈥楨nLichenment鈥�. And, puns aside, there鈥檚 a lot to see here, once you take the time.
"If you've looked at lichens, you may have seen British soldiers with the red tips. That's a fruticose lichen. That's one that's upright. Fruticose are three dimensional," Pengel said.
Enking: British soldiers is the name of a lichen?
Pengel: Yep, because it has red little pegs with red heads on it.
There are some 15,000 varieties of lichens that cover around 10% of the Earth鈥檚 surface. Not to be confused with moss, lichens are their own thing 鈥� and they actually aren鈥檛 plants at all. They鈥檙e made up of two or more parts: an algae and a fungus working in close symbiotic relationship. Pengel calls this the 鈥榣ichen sandwich鈥�: you have the fungus, the algae, and then, more fungus.
鈥淲hen the fungus gets wet, it tends to become transparent. Well, why would it do that? Well, there's algae underneath. So what do the algae do when they have water and light? They photosynthesize."
The fungus protects the algae, and provides the lichen's structure.
Lichen can also act as a sort of air conditioner for the forest: it stores and releases moisture, making the air wet, dry, warm, or cool. A forest that has lots of different lichens is a good indicator of air quality, biodiversity and a healthy ecosystem, Pengel says.
鈥淭here's a lot of stuff that not just eats lichen, but lives in it, and most of those are microscopic, so they're the very base of the food chain," Pengel said. "And if you remove that base of the food chain, it's kind of ecology 101, if you destroy the base of the food chain, the whole pyramid starts to collapse. And if we don't know what we have, we don't even know what we're collapsing or what we're losing.鈥�
Scientists are currently studying how lichens are being affected by climate change. Daniel Stanton at University of Minnesota is one of the foremost ecologists on this beat. He says lichens present a strange paradox: one the one hand, they're very vulnerable to their surrounding climate.
鈥淎ll of their water, all of their nutrients are coming off of the dust and what's in the air, they don't have roots that they can tap into the ground. They can't tap into supplies of water. They have to really kind of experience the environment that's right there in front of them.鈥�
But, at the same time, they can also be extremely resilient: they've even survived being sent up to outer space.
鈥淲hile they're dry, they're almost not quite bomb proof, but they're, they're really unbelievably tolerant of almost everything.鈥�
Scientists are still learning how the warming climate is affecting lichens, and findings are mixed: some research predicts that many lichen won't survive a certain threshold of warming 鈥� Stanton said somewhere around 2.5 degrees Celsius is a sort of tipping point. But other more hopeful theories suggest that lichen might be able to adapt to temperature changes, by swapping out the algae in the "lichen sandwich."
"There's some evidence that this plays out with some corals. They're in some ways one of our closest analog organisms," Stanton said. "And what people have been showing with corals, increasingly, is that in some cases, you can swap out the photosynthetic partner and bring in ones that are better adapted to warmer temperatures."
So, there's a change for lichens to switch from maybe algae that are more cold-adapted to ones that are more warm-adapted. But this is still speculative, Stanton said.
Naturalist Jeff Pengel said he could see the lichens migrating north in search of their preferred climate. And because lichens are a food pyramid base, that could change how our ecosystem here in New England looks.
"Over time we would expect that those warmer weather species will continue to go north, which is going to change the basic ecosystem," Pengel said.
"Does that mean everything's going to die? Probably not, but it does mean that the organisms that we see today could be dramatically different in 100 years, if climate change continues at the pace it is at least in the past couple decades," he said.
Pengel said, while lichens are often hidden underfoot, they deserve a closer look 鈥� and he said he finds something new on every hike.
