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Faculty spotlight: Don Waller, steward of Wisconsin forests

July 26, 2011

If a tree falls in a forest, Don Waller is likely to hear it. Or at least hear about it.

From an office on Bascom Hill appropriately canopied by a massive white oak tree that he helped to save from removal, the UW-Madison professor of botany and environmental studies has his finger on the pulse of forest ecosystems in Wisconsin and around the world.

Don Waller lab
Don Waller (back, far right) with current lab members.

Waller and a team of six students and four postdoctoral fellows study the nature, extent and causes of long-term ecological change within forest communities. They examine the impact of habitat loss, deer overabundance and other factors. The Waller lab's research carries important implications for how best to manage these ecosystems in the face of a changing landscape and climate.

"We have a conversion going on in nature," Waller says. "We know that many of our environments are becoming simpler - they're losing native species, they're gaining exotic species, they're losing rare species... The goal of our studies is to understand what are the ecological drivers and particular mechanisms causing that change."

His findings have been applied locally, nationally and globally, helping state and federal agencies link forest and game management to conservation biology.

Waller currently collaborates with the U.S. Forest Service on climate change mitigation and adaptation in northern Wisconsin's Chequamegon-Nicolet National Forest, with the National Park Service on methods for monitoring vegetation changes and deer impacts in the Great Lakes network of national parks, and with the Wisconsin Department of Natural Resources on deer management. His decades of research on how overbrowsing by deer affects tree regeneration and plant diversity in Wisconsin forests helps guide the DNR in making ecologically informed management decisions.

"That has gotten me and my team more involved in the Wisconsin idea," he says, "trying to apply our understanding to the management of wildlife and forests here in the state."

Led by Leopold

Waller, who has been at UW-Madison since 1978, credits several graduate students in the 1980s, who were concerned about the impacts of overzealous logging in northern Wisconsin, with steering his research focus toward forest management.

"I began to look more intently not just at the individual species that I had studied through the first half of my career, but more at the systems - the communities, the ecosystems - that provide the context for the ability of these species to exist," Waller says.

Don Waller

If this holistic approach to conservation sounds familiar - it was the vision of legendary ecologist Aldo Leopold - it's no coincidence. Leopold's land ethic has not only guided much of Waller's career, it drew him to the university.

"I was predisposed to accept a job in Madison, Wisconsin, in part because my ecology professor when I was an undergraduate had given me A Sand County Almanac," Waller says, referring to Leopold's landmark collection of essays.

"It's so lyrical, it's so simply informative and it's so deeply knowledgeable of all natural history that it gave me hope," he adds. "Since that time, I've learned much more about Leopold and his legacy."

Waller continues to find inspiration in Leopold's writing and in his ability to arouse interest in natural history on the part of others.

"I could give you another ten examples on ways in which Leopold has inspired me, both in terms of his science and in terms of his deep desire to get people to do the right thing.

"He didn't just work in remote ecosystems, he worked on local farms," he continues, describing Leopold's field experiments in the 1930s and his hands-on work encouraging farmers to manage their land in a way that fostered habitat while maintaining productivity.

"That's what I'm trying to do with forestry and foresters," Waller says.

Past, present and future

While Leopold stoked Waller's passion for a career in conservation, another eminent ecologist laid the foundation.

John Curtis records
Curtis's original dataset is archived
in Birge Hall.

In the 1940s and 50s, UW-Madison botanist John Curtis undertook a broad and detailed survey of Wisconsin landscapes and vegetation, resulting in a carefully archived goldmine of data, as Waller describes it, and Curtis's seminal book The Vegetation of Wisconsin.

Waller and his students are now resurveying many of the same forest communities that Curtis and his students visited throughout the state, collecting data to track more than 50-year changes.

That assignment presents a number of challenges - for example ensuring that researchers have located the exact site that was previously sampled, resampling it with the same techniques, and matching species names from 50 years ago to species names from today.

Colleagues and the lab have now resurveyed more than 340 sites in Wisconsin. They often find declines in plant diversity and increases in weedy invasive exotics - potential red flags for an ecosystem's sustainability. They are now working to identify the specific factors driving these changes and why some species are declining while others are increasing.

"We compare sites to see which have gained or lost the most or homogenized the most, and now we're comparing species," Waller says.

Waller's lab is now pursuing detailed studies of how particular plant traits like dispersal ability affect the ability of different species to persist. On a broader scale and with other UW-Madison researchers, Waller's team is investigating how these dispersal traits affect patterns of gene flow and the ability of populations to retain genetic variation. They are also developing a phylogenetic (family) tree for all 2,500 native and introduced plant species growing in Wisconsin.

This research, supported by a five-year, nearly $3 million grant from the National Science Foundation Dimensions of Biodiversity program, will provide important new insights into how genetic connections and physical traits affect a plant species' distribution and its response (or vulnerability) to environmental change.

Of common concern

Like the mentors before him, Waller is also working to inspire understanding and concern about environmental conservation among the broader public.

The Vanishing Present

Waller coedited and contributed several chapters to the book The Vanishing Present: Shifts in Wisconsin's Lands, Waters, and Wildlife, which examines changes in Wisconsin's ecology and offers insights into the state's future. While the book includes commentary and analysis from a distinguished and diverse set of scientists, naturalists and policy experts, it was intended as an accessible case study for the public. In the book's conclusion, Waller writes, "If you are now more aware of and interested in Wisconsin species and habitats and how they have changed, this book has been a success."

For nearly 30 years, Waller has also led a popular introductory ecology course aimed at UW-Madison students from outside biology and environmental studies.

"I take teaching of that course very seriously," Waller says. "My pet name for it was 'ecology for voters' and I could have called it 'ecology for citizens.' Ecology provides a lens for looking at the world, and that's the lens I wanted to give to the students."

Course content ranges from activities aimed at becoming a keen observer of nature to lessons in the environmental crises facing the state and the world and how individuals can have an impact.

"I feel as though our current generation faces an exceptional challenge in coping with what's going to obviously have to be a very radical and very abrupt transition," he says, referring to the magnitude of changes occurring in our environment today. He is troubled, he says, by how dimly aware many people are of these changes.

"Because some of the changes are subtle, because some of the changes are slow, because some of the changes are complicated, they're not easy for the public to grasp," he says. "But the implications are quite serious."

While Waller is concerned for the future, he shares an equally long list of points of encouragement.

Don Waller

The success stories of resilient species, such as the recovery of the sandhill crane and the rebounding of the gray wolf population in Wisconsin; the increasing popularity of citizen science programs; the inception of the undergraduate environmental studies and environmental sciences majors at UW-Madison, combined with students' intense interest in the field; and the strong graduates coming out of the Nelson Institute's certificate and degree programs all give him hope.

"I think the Nelson Institute and this university are very uniquely poised to give students a broad understanding of these challenges and the science and social science and even humanities behind what's going on," he says. "We're putting the pieces together."

And Waller continues to draw energy from his initial source of inspiration, Aldo Leopold. Where Leopold and his family originally sought a weekend refuge - a re-built shack along the Wisconsin River that became a living laboratory for Leopold's relationship to the land - Waller now finds an occasional respite.

"It's a place I like to return to," he says. "You realize that the simple things around you warrant deep study and consideration, fostering a deeper train of thought."