Climate change is affecting seasonal indicators. How phenology helps track those impacts
On Saturday, I took advantage of the sunny weather to make the trip to Letchworth State Park to learn more about a pertinent topic amid this abnormally warm and snowless winter: phenology.
Part of the park’s free Winter Lecture Series, the Phenology of Climate Change was hosted by Lara Hargrave, an environmental educator with New York State Parks, Recreation and Historic Preservation.
But what is phenology? It is the study of plant and animal life cycles in relation to the seasons, according to the U.S. Geological Survey. It’s also described as nature’s calendar, identifying when seasonal transitions occur, like birds nesting or leaves changing, by the USA National Phenology Network.
While phenology has a long history, with observations of migration and first appearances documented by everyone including author Henry David Thoreau, it has a more pressing use today.
“By making phenological observations, we can better understand how organisms are responding to climate change,” Hargrave said.
Spring timing and climate change
An example of changing behavior among a common native species is the spring peeper, little frogs with a distinctive sound that are a typical indicator for their eponymous season. Phenological records from the early 1900s indicate spring peepers, and three other native frog species, are calling 10 to 15 days earlier today.
Other changes have been noted by these observations of nature, including the earlier budding of some tree species in the spring. A study compared the budding times for tree and shrub species in Thoreau’s observations at Walden Pond in the 1850s to the same location in 2009 and found those same woody plants leaf out an average of 18 days earlier, detailed in “Walden Warming: Climate Change Comes to Thoreau’s Woods” by Richard Primack.
These earlier leaf out dates in the northeast United States have impacts on other native species, including wildflowers, which have been less strongly affected by the changing climate, Hargrave said. This means a narrower window of sunlight for some flowers once they’re shaded by trees.
“That is a troubling thing for a wildflower,” Hargrave said. “It means they have less energy to allocate to the future to grow for reproduction and defense … Their survival is threatened by this happening.”
Are birds migrating earlier in the year?
It’s not just flora that have been affected by anthropogenic climate change, as the return dates for migratory birds have been affected as well. A 2022 NASA study found bird migration in the east and west United States are impacted by climatological conditions. Warm land and sea temperatures spur earlier arrivals in the west and Rossby waves — high latitude westerly winds — affect migration timing in the east.
With some birds staying later into the fall before their return trip south and plants producing fruit sooner due to the earlier start to their growing season, this can lead to missed timing on one of the high calorie foods many species of bird rely on.
“So when they do go on their migration, all that’s really left for many of them are the fruits of the invasive species, which are persisting for longer, partly because they're not as nutritious, they’re not as attractive,” Hargrave said. “And one of the problems with this is that it helps disperse these invasives even further and really helps propagate them.”
All of these variables have to be considered by land managers, who are faced with the reality of a changing climate while balancing conservation and stewardship.
“Do you try to predict what’s going to thrive there in the future?” Hargrave said. “Do you try to preserve what you have now?”
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How you can help: Citizen observations
Data about phenological changes comes from a variety of places, including everyday citizens with knowledge of their region.
“If there’s a favorite place you go to, somewhere you visit all the time, you probably know better than anyone, you’re the best person to make phenological observations there,” Hargrave said.
The USA National Phenology Network has created a community science project, Nature’s Notebook, which empowers local observers to document backyard observations of seasonal events through their website, usanpn.org/nn, or using the app of the same name. The data is used to create a nationwide view of current phenological conditions and aid researchers. There are even specific campaigns for areas of interest like pollen, nectar sources and leaf outs.
Hargrave said she’s planning for volunteer trainings about recording phenological observations, including how to fill out the data sheets. There’s no need for existing knowledge, just an interest in the natural world or the effects of climate change.
Instead of focusing on the aspects of anthropogenic climate change out of individual’s control, recording phenological observations is an opportunity to focus on what the community can accomplish together, Hargrave said.
— Steve Howe covers weather, climate and lake issues for the Democrat and Chronicle and he had a binder full of Franklin Mountain Hawkwatch data as a kid. Share with him at showe@gannett.com.
This article originally appeared on Rochester Democrat and Chronicle: Tracking NY climate change through phenology and citizen science
