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Ringing In the Old

by Mary Shafer

Susy Ziegler

Susy Ziegler
Photo by Leo Kim

Susy Ziegler

Assistant professor, geography


M.S., Ph.D., University of Wisconsin– Madison; B.A., Dartmouth College

Professional history

Old growth forests, teaching

Role models

“My parents had a very strong influence on me. My dad helped me understand things like how glaciers were formed, but he didn't know I'd make a career of it. I think he would have preferred a more, well, practical career. But I didn't have that kind of engineer's practicality. My four-year-old son knows pulleys and levers. But I wasn't like that.”

On teaching

“The physical environment is far away from the real world for most students. My goal is to bring material to life with real-world examples and ultimately to make them better global citizens.”

On research

“I can go into a forest and understand the part of the world it's in. That's my excuse to do field work.”

A few hundred miles from the Boston area where Susy Ziegler grew up, the 2-billion-year-old Adirondack Mountains stretch out over some six million acres of northeastern New York. This is home for the moose, coyotes, and several dozen other kinds of mammals that roam among the area's towering white pines, aspens, and sugar maples. For Ziegler, it is a research lab.

“I go into the forest to understand that part of the world and how it has changed,” says Ziegler, an assistant professor now in her third year on the faculty of CLA's nationally renowned geography department.

Her specialty is biogeography, a research passion that sprouted in her childhood on long family car trips with her engineer father and science-teacher mother, and intensified both in her undergraduate days at Dartmouth and in graduate work at the University of Wisconsin–Madison.

Part cartographer, part historian, part detective, the biogeographer tries to unearth the story of a habitat. Which trees in this forest are the same ages? When were there spurts of regeneration and why? What are the patterns of life and decay over space and time? Why did certain vegetation grow here and not there? Ziegler and her colleagues sleuth out answers by looking for clues in the organisms themselves. Take tree rings, for example.

Any kid who has climbed atop a tree stump knows that a tree reveals its age by the number of its rings—one for each year of life. To the untrained eye, that's about all there is to see. To Ziegler and her very trained eye, however, tree rings are the starting point of a much more elaborate story, one she begins to piece together by extracting hundreds of pencil-shaped dowels of wood from living trees, sanding them in her lab, and examining them microscopically.

“The rings in these cores can help us figure out rates of disturbance, bursts of growth, and growing conditions,” Ziegler says. "From there, you can deduce other things. A burst of growth might tell you, for example, that there was a fire here, that trees were felled, and sudden bursts of sunlight stimulated growth.”

In her graduate work, Ziegler took to the Adirondacks, where she used tree-ring analysis to reconstruct 140 years of natural disturbances in the life of the forest. She also compared patterns in old-growth areas with newer second-growth patches that had regenerated following logging-related fires in the early 1900s.

Now cut to Minnesota, where Ziegler has brought her research interests to native terrains like the Boundary Waters Canoe Area and the lesser-known Kellogg-Weaver Dunes in the southeastern part of the state.

It's new turf for this young researcher, and although she's only just begun work with U Forest Resources colleagues in the Boundary Waters—with its terrain much like that of the Adirondacks—she has been captivated by the desert-like dunes in Wabasha County. Created by an ancient receding Mississippi River, the dunes are bordered by oak savanna, whose history Ziegler hopes to reconstruct with the aid of her tree-ring analysis.

The practical applications of Ziegler's work are significant for preserving ecosystems. "Some people say the ecosystem will take care of itself,” she says, "that once a forest starts to regenerate, it will be OK. But if we study real old-growth forests, we might be able to get information that we can apply to a younger, regenerating forest to give it old-forest characteristics. We could create the habitat for organisms that seem to be found only in old-growth forests—like the spotted owl, for example, or certain mosses and lichens on the East Coast.

“And we also want to study the regeneration process itself,” she says. "What trees are coming back at what density? Seeing what happens after a disturbance such as a fire can inform our decisions about the future,” she says.

If there is anything more stimulating to Ziegler than her research, it is teaching, a passion she has nurtured since the days when she played school with her younger brother and sister, using an old-fashioned wood and metal desk and always insisting on being the teacher.

“I remember going home for Thanksgiving my first year of college,” she says, "and getting blank stares when I said I was interested in geography. My relatives wanted to know, ‘What can you do with that besides teach?' I said, ‘What's wrong with teaching?' I wanted to teach.

“In truth, though, geography trains you for almost anything in the public or private sector. The question should really be, ‘What can't you do with geography?'”

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