As swings in temperature become more common due to climate change, the lifecycle of nature starts to shift.
A University of Wisconsin-Milwaukee researcher is studying how trees and shrubs are affected by changing weather.
Alison Donnelly is researching one particular natural area on Milwaukee’s east side — Downer Woods. And, her research is now playing a role in a national project.
Donnelly visits Downer Wood twice a week.
Right now, it’s looking bedraggled. "The tree cutters are here so they’re going to take out the dead and the dangerous wood,” Donnelly says.
The 11-acre parcel was home to a great many ash trees. Over the last few years, most succumbed to deadly invasive Emerald ash borer beetles.
“We’ve had a lot of incidents where the trees have fallen over the path,” Donnelly adds.
She moves throughout the woodland— clipboard and binoculars in hand — taking a close look a trees tagged with metal discs and shrubs adorned orange ribbons. She has marked them to study over time.
When she joined the UWM geography faculty in 2015, trees were getting all the attention, until Donnelly says, “I had a student that skidded into my office in early spring saying that she wanted to do a project on phenology.”
That’s the study of the timing of key life cycle events for animals and in this case plants. For example, when leaves begin to bud.
“We came out here to Down Woods and we looked at the trees and the trees are still completely dormant. So I just had the idea and said, ‘Look, let’s not panic, we will start monitoring shrubs,” Donnelly recalls.
That was 2017.
“Her name was Kaleigh and she just took to it with gusto. She would come out three or four times a week and she would observe how the buds started to open and the leaves started to develop from those buds,” Donnelly explains.
When Kaleigh graduated, Donnelly picked up where she left off — monitoring and writing papers about the findings.
“We’re trying to identify any differences in the timing of when leaf out occurs in spring. We’ve added the autumn season so that gives us an indication for the whole year and it gives us the lengths of time, the time that the shrubs are active, and trees,” Donnelly says.
Trees are prized for their capacity to store carbon dioxide, but Donnelly says shrubs also play a role.
“Standing here today, you can see that those trees are still dormant, but the shrubs are sequestering carbon dioxide out of the atmosphere. The leaves are fully out, they’re photosynthesizing like crazy. So, it’s at the extremes of the growing season when the trees are still leafless that the shrubs are important,” Donnelly says.
The environmental scientist says she needs to amass a lot more data to project how woodlands will hold up as a climate change mitigators.
But Donnelly says this past El Nino-dominated winter could give a sense of what might unfold. Here in Downer Woods, “we observed bud burst on some of our shrubs in February. In a normal year, we would not expect that until very late March or April,” she says.
Recently Donnelly joined forces with up with a cadre of scientists from around the region.
“The National Ecological Observatory Network Great Lakes User Group. So that’s a bit of a mouthful, but we call it GLUG for short,” Donnelly says.
Each member brings a diverse range of expertise to the table. “So we’re doing stuff with the plants. There are other people doing work with the lakes, the ice and off. Someone else is working on soil respiration,” Donnelly says.
The researchers are exploring the impacts of this extreme winter on the natural world. It’s one step in shedding light on intricate and increasingly challenged ecosystems.
“We’re trying to understand how a forest ecosystem will respond to future environmental change. Now, obviously climate change is the main driver. We want to know what’s going to happen in future and how vulnerable these ecosystems are — and believe me, they are vulnerable,” Donnelly says.
That means what happens right here in Milwaukee at Downer Woods could help us answer some important environmental questions.
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