Mount Auburn Cemetery is known for its lush landscapes, bird-watching and, of course, its buried occupants. It’s also a place where scientists hope a tiny creature could help cut how much carbon is released into the air.
On a recent morning in Mount Auburn, ecologist Brooks Mathewson took out a Ziploc bag holding wet paper towels. He gently shook the bag and a small, unassuming amphibian squirmed its way out. It’s an Eastern red-backed salamander. Topping out between 2 to 4 inches long, its size obscures its authority — and voracious appetite.
“The wolves of the forest floor, I like to call them,” Mathewson said.
Red-backs are the most abundant salamander in any healthy forest and a top-level predator: One salamander eats about 20 bugs a day. While Mount Auburn Cemetery in Cambridge and Watertown is a final resting place for many, it’s also where Mathewson is hoping to breathe life into this amphibian’s population. Since the fall of 2017, he has released close to 80 of these salamanders into the cemetery as part of a larger, long-term project to restore native plants and creatures in areas throughout Mount Auburn.
Red-backs are easy to find in any healthy New England forest. It’s almost certain they called Mount Auburn home over 100 years ago until development drove the population out. The cemetery’s location in the midst of an urban industrial setting at the time made it impossible for the population to reenter. Mathewson is trying to change that.
“Red-backs are often looked at as an 'indicator' species — a species that tells us a lot about the health of an ecosystem,” he said.
Now that the cemetery is a suitable habitat again, Mathewson said, they can be reintroduced and signal how the forest is doing over time. And the salamanders' taste for bugs could be significant in reducing how much carbon is released into the air.
“About 15 percent of the carbon that we emit now as humans in the United States is absorbed by forests, and a big component of this is keeping carbon in the soil and not having it go back into the atmosphere,” Mathewson said.
Two to three times as much carbon is stored in the soil as in the trees above them. In autumn, when trees lose their leaves, a lot of carbon is still stored in those leaves. And when bugs and beetles chow down on them at high speed, carbon is rapidly released into the atmosphere. But when the Eastern red-backed salamanders enter the picture, they slow the decomposition rate by preying on those bugs. That's why these amphibians are crucial to keeping carbon in the soil.
Richard Primack, a biology professor at Boston University, said while bringing in new populations of red-backed salamanders is a good idea and makes ecosystems species-rich, it’s not going to really solve the world’s climate change problems.
"Scientists are very concerned about methods to increase the ability of plants to absorb carbon dioxide and to store carbon dioxide in the soil, but the world’s climate change problems are really caused by the massive destruction of tropical rain forests in countries like Brazil and Indonesia, and it’s caused by the ever-increasing use of fossil fuels like oil, coal and natural gas," Primack said.
Red-backed salamanders also have a unique characteristic: they don’t breed in water. Bryan Windmiller, director of conservation at Zoo New England, said this trait allows them to freely roam the forest floor, but it also gives them an advantage in more urban areas.
“Red-backed salamanders are the only ones in Massachusetts that don’t breed in water. They are hearty in terms of dealing with the effect in what we humans do to the landscapes,” Windmiller said. “They have simple habitat needs. All other amphibians have to make their way to water to breed.”
Consecration Dell is a short walk from the cemetery’s main entrance. It’s a wildlife oasis with lush plant life and a vernal pool. Mathewson veers off the pathway to where several numbered cover boards are placed on a small hillside.
“This is mimicking coarse woody debris, so it’s mimicking what their habitat would be under a log or rock. So we’re going to go and release this salamander right below one of the cover boards and we’re going to make note of where he was released,” Mathewson explained.
He lifts a cover board and places a 1-year-old salamander underneath. It immediately burrows under the leaves and disappears. Mathewson isn't sure if he’ll see this particular salamander again, but he’s confident the population has been established since the project began a year and a half ago.
“We’re finding them under the cover boards fairly often," Mathewson said. "But when the soil dries out, they move deeper into the forest floor. Or if it’s really wet, they’ll be in the leaf litter and not under the cover object. So you don’t sample the entire population when you look under these cover boards. But this is a good home base to have.”
While unleashing an army of red-backed salamanders may not save the planet, Mathewson said taking care of our forests is a step in the right direction.
“We’re going to have to figure out how to get the carbon that's in the atmosphere now already, out of the atmosphere," he said. "And one of the big tools that we can use to do this are having healthy forests.”