Over the past six years, thousands of hikers have snapped photos of plants and animals on the Appalachian Trail.
They’ve uploaded those photos to an app called iNaturalist, which records their coordinates. The app’s technology, as well as other naturalists, have helped confirm the types of flora and fauna in the photos. That’s created mountains of data for researchers to wade through: more than 50,000 observations of 3,400 species.
Those photos, along with other observations taken by naturalists at sites in the White Mountains since 2004, paint a portrait of how climate change is transforming one of the most famous hiking trails in the U.S.
As temperatures warm, spring is arriving earlier and plants are responding to new signals. The timing of when they put out leaves and flowers — known as their spring phenology — is shifting earlier, according to research published in August by Appalachian Mountain Club scientists.
Plants started growing leaves and flowers three to six days earlier per degree Celsius of warming, the researchers found. In the northern part of the trail — including parts of New Hampshire, Vermont, Massachusetts and Maine — understory plants were affected by early springs more than trees were.
“You can think of the timing of these events, this phenology, as sort of like a bioindicator for change. It's like taking a pulse of climate change,” said Jordon Tourville, a terrestrial ecologist for the Appalachian Mountain Club.
For the northern part of the Appalachian Trail, understory plants are gaining more time to soak up the sun before tree canopies close over and shade them in. That could be a benefit for plants, which need that time to photosynthesize and grow.
But, Tourville said, there could be downsides. If plants flower earlier, they may miss their pollinator partners. And they could be more vulnerable to frost events, which are still a risk in spring.
“It would only take one really cold night after a plant has flowered and leafed out for those flowers to be knocked off,” he said. “All that reproductive effort is wasted.”
The northeastern part of the country the Appalachian Trail slices through is warming faster than other parts of the U.S.
Tourville said Forest Service officials could use the research on spring changes to better manage the land through warming seasons. They could support pollinators, help reduce the stress that plants experience, even collect seeds and grow plants in greenhouses that could be at risk of disappearing.
For now, Tourville says, he wants people to be aware that plants on these trails are experiencing big changes, and monitoring their life cycles can help.
“It’s important that we monitor phenology because that’s the indicator of change,” he said. “We identify those species and areas that are responding the most to climate change. Then we can try to address the stressors to those species that would cause them to maybe start to blink out in certain locations.”
Hikers, he said, can help, as long as they can take pictures of the plants they see.
“The more awareness we have, the more people have iNaturalist downloaded and are subscribed to our projects — the amount of data just balloons out and we're covering areas that we never were able to before,” he said.
