Climate change is creating extreme weather, but it may also be having an effect on what you put on your pancakes. Researchers from Memorial University of Newfoundland have found that sugar maples may have more trouble responding to warming temperatures than originally thought.
“We would expect the whole species distribution to shift northward,” says Carissa Brown, an assistant professor of biogeography. But Brown and her team have found that factors other than climate are affecting sugar maple’s ability to “migrate” in response to climate change.
In a series of what Brown described as “character building” experiments, her team lugged about 800 litres of earth up and down the kilometre high Mont-Megantic in southern Quebec. Doing so allowed the team to simulate northward migration by simply changing elevation. Instead of moving the soil to higher latitude, they took it up the mountain where the temperatures were comparably cool.
To ensure their results were being determined by factors other than climate, they brought soil from high on the mountain, outside the sugar maple’s range, down to the heart of the tree’s range and planted the winged seeds kids often call “helicopters.”
They found that even in the best climatic conditions, planting seed in soil from outside the tree’s range resulted in less seedlings taking root, meaning trees would naturally have problems expanding their range. But the real surprise was waiting for the scientists at the top of the mountain, where they’d transported the good soil.
“We came to our pots and instead of finding seedlings we found the seed wing, but instead of a seed attached to it, we found little bite marks,” Brown says.
Whatever was eating the seeds was stifling the sugar maples’ range expansion more than other factors such as soil quality. To prove it they ran another series of experiments using cages to protect some seeds, and found that when protected and planted in good soil, the seeds would germinate at high elevation.
Brown says the research shows that the idea that trees and plants will simply move north as the climate warms is too simple. And that there will probably be a time when sugar maple range is squished between a warmer climate to the south and obstacles such as seed predation or soil quality to the north. Nicely described