Tracking Shifting Seasons

Spring came to the Southeast three weeks early this year, and a burgeoning citizen science effort in the Great Smoky Mountains National Park aims to put a bead on whether seasonal patterns are shifting for good.

For four years, the park has been training volunteers to collect tree phenology data —information that indicates the passing of the seasons, such as when trees begin to flower, leaf out, or change color. 

Volunteers are assigned to one of 28 sites park-wide to keep watch at regular intervals, and the resulting data is sent on to the National Phenology Network, which compiles similar information from locations across the country to get a big-picture view of how the seasons shift. 

“The more data you get, the more likely it is the story that’s shaping up is valid,” explained Susan Sachs, education coordinator for the park’s Appalachian Highlands Science Learning Center. “Individual people may make mistakes, but if there’s enough data that noise gets canceled out.”

So far, data indicates that a new seasonal pattern marked by earlier springs could be forming in the park, Sachs said, but it will take another 5 to 7 years of data to know for sure. 

The volunteer-collected data is supplemented by information park scientists are gathering on the seasonality of everything from wildflowers to migratory birds—because it’s all connected. If spring comes early enough that a hard freeze in May kills all the fruit, for example, wildlife such as black bears could have a hard time finding food later in the year. That could result in increased bear nuisances come fall.

Seasonal shifts also have a tremendous impact on how and when the park’s 11 million annual visitors show up. The better the park can predict when fall colors will peak or wildflowers start to bloom, the better it can serve the public.