College of Agricultural and Life Sciences

College of Agricultural and Life Sciences

Above ↑ The vast expanse of wilderness near Thompson, Manitoba, is a living laboratory for forest ecologist Tom Gower. From towering evergreens to delicate lichen (above), the world’s boreal forests play a key role in counteracting the effects of global warming. Trees and other plants absorb carbon dioxide from the atmosphere, while lichen add nitrogen to the soil that nourishes other plants. Gower is warming small sections of forest to better understand how global climate change will affect this important biome.

We Really Need These Trees

Home >>We really need these trees

Nine hours north of Winnipeg, where the paved road ends,
sits the quiet mining town of Thompson, Manitoba, Canada. It’s a long way from Madison, but Tom Gower knows the road well. Since the early 1990s, the Kentucky-born forest ecologist has been traveling to Thompson and other Canadian research sites, where he works to unlock the secrets of climate change held by the northern forests.

The wilderness around Thompson is part of the boreal forest, a band of
predominantly evergreen trees that stretches around the globe, covering large parts of Canada, Alaska, Siberia, China and Scandinavia. With its huge tracts of undisturbed land and freshwater lakes and streams, the boreal forest comprises the world’s second largest biome, home to vast numbers of plants and animals.

It’s also the source of natural resource products that we use every day. Canada exports millions of dollars worth of timber products to the United States every year. Rivers in the boreal forest generate hydroelectricity that helps power homes and businesses across the United States.

The Earth’s carbon stash

But Gower’s interest in the boreal forest lies not in what it produces but in what it stores.

“The boreal forest plays a pivotal role in the global carbon cycle,” Gower explains. “It’s a massive carbon sink — meaning it traps carbon instead of releasing it into the atmosphere.”

Keeping carbon out of the atmosphere is essential, Gower points out.

“Human activities that burn fossil fuels release gases, some of which contain carbon, into the atmosphere — called ‘greenhouse gases’ because they contribute to the overall warming of the earth,” he explains.

Although the cause is sometimes disputed, there are plenty of signs that average temperatures across the world are rising, says Gower: “Ice is forming on lakes later in the winter and coming off earlier in the spring. Birds are migrating south later and returning north earlier. And trees are leafing out earlier.”

As the planet grows warmer, ecosystems must adapt. In North America, this may mean that some species will expand their ranges, while others will be forced farther north. When this happens, says Gower, it’s unlikely the ecosystems involved will remain unchanged — and that is cause for concern.

“These systems are based on intricate, symbiotic relationships between plants, fungi and animals. Consider the way certain insects are perfectly equipped to pollinate a certain species of agricultural crop. What would happen if those relationships changed?”

A hotter, drier climate could have devastating effects on water reserves — even in Wisconsin, which historically has had an abundant natural supply of water. “Water is possibly our most precious natural resource,” Gower says. “In a warmer climate, we will have trouble.”

The lungs of the biosphere

Also worrisome is the prospect of changes in the makeup of the atmosphere. Forests are the “lungs of
the biosphere” and have a pronounced influence on atmospheric chemistry, Gower explains.

“During years with severe forest fires, increases in carbon dioxide can be detected anywhere in the world,” he points out.

And environmental changes often have economic consequences.

“A warmer climate could affect prices of all of our natural resource products,” Gower says. As ecosystems change, prices for wood products could rise, he notes. If water supplies run short, the cost of irrigating crops would go up, which would drive up prices at the grocery store.

The boreal forest is on our side

However, Gower is quick to point out that the effects of global warming can be mitigated. For example, plants play a key role in counteracting global warming because they absorb carbon dioxide from the atmosphere.

“If there were no vegetation to take up carbon dioxide, presumably the climate would get warmer and warmer,” Gower explains. And among plant systems the boreal forest is a top performer when it comes to carbon storage.

“The boreal forest has a disproportionately larger amount of carbon in the soil than almost any other biome,” Gower says. “It takes in about four-tenths of a metric ton per hectare (about 2.5 acres) per year.”

That may not seem like much, until you multiply it by the many millions of hectares covered by the boreal forest. This makes this forest one of the most important regions — if not the most important — when it comes to carbon storage.

The reasons for this have to do with climate. Plants typically release stored carbon after they die, when the process of decomposition breaks down leaves, roots and branches. However, the growing season in the far north is short, so the litter of dead matter that falls to the soil has little time to decompose. In addition, tracts of soil in the boreal forest remain frozen year round, and high water tables elsewhere deprive the soil of oxygen. Both of these conditions slow the loss of carbon to the atmosphere.

As a result, the boreal forest stores more carbon than it releases.

But what if this changes? What if — as the environment warms, the growing season lengthens and frozen ground begins to thaw — the forest starts to release the carbon it holds?

Gower’s research team wants to understand the consequences. And they aren’t waiting for nature to take its course.

Creating not-quite-global warming

“We’re trying to be Mother Nature,” Gower explains. “We’re warming trees, air and soil and trying to understand how that affects the balance of carbon.”

Funded by the U.S. Department of Energy and Manitoba Hydroelectric, in 2001 Gower established a research site near Thompson, Manitoba, to investigate the exchange of energy, carbon dioxide and water between the boreal forest and the atmosphere.

Gower’s initial efforts looked at the importance of wildfire in the overall forest system (see sidebar on page 9). For his latest project, wanted to set up massive chambers to warm an entire forest system — air, soil and plants. The plan called for burying heating cables in the soil and erecting heating chambers around existing trees. This was an innovative proposal. No previous forest warming study had attempted to heat air as well as soil — at least not on the scale that Gower was suggesting.

How to heat the soil

A key objective of Gower’s experimental design was to minimize disturbance to soil and the roots that run through it. In previous soil-warming projects, researchers had simply dug trenches to place the heating cables. “When you dig through the soil to make a trench you cut tree roots and disturb the whole system,” Gower points out.

Gower’s team first tried a directional bore — a tunneling drill used to run cables under obstacles like roads, lakes and wetlands. However, after hauling the smallest drill available (supplied by the Case Corporation in Oconomowoc) all the way to Manitoba, they were foiled. The tool wasn’t designed to work at the shallow depth at which they needed to set their cables — the drill kept popping out of the soil.

So Gower and construction engineer Carter DeDolph brainstormed a new solution: They combined an 80-pound drill designed for diamond mines with a hydraulic carriage and extension bits for Milwaukee rotary hammer drills. The result? A device that could lay 10,000 feet of heating cable a few inches below the surface without popping out of the soil or destroying tree roots.

This time they tested their system at the College’s West Madison Agricultural Research Station. They were grateful for the test space.

“Without West Madison I would have had to run the tests in my own backyard,” Gower says with a laugh.

The Thompson research site features four 15-meter-by-15-meter heating plots — also designed at the West Madison Research Station with the help of construction engineers Carter DeDolph and Myron Tanner. Each plot includes a chamber that encloses about 10 trees. Air and soil in each chamber can be heated up to 5° C degrees above ambient temperature.

Probes monitor the temperature of the soil and air inside and outside the chambers. Every 10 to 30 seconds, a computer determines whether the chambers are too warm or too cool. The computer (using software designed by Tanner) controls vents, heaters and fans to adjust the temperature.

Of course, this setup didn’t come cheap. Gower is grateful for support from the Department of Energy and other partners.

“For example, the Manitoba Hydroelectric Company donates the energy costs for the project, including bringing in the power lines and providing the energy to warm the plots. They’re an environmentally conscious company, and are good stewards of the land. They’ve been wonderful
partners,” he says.

Some interesting early results

After a year of data collection, Gower has already seen what he calls a dramatic increase in phenology — a correlation between climate and biological phenomena — in the heated plots. Tree shoots, flowers and shrubs in the warmed plots start growing about three to four weeks earlier than in the control plots.

Some of the early data suggest that warmer temperatures could actually enhance the biome’s ability to store carbon.

“One area of concern was what would happen to the carbon in the soil if the climate warms — will decomposition, and therefore carbon loss to the atmosphere, increase?” Gower says. “Our preliminary data suggest that this may not be the case. In fact, increased plant growth means the boreal forest will take in more carbon dioxide, and may actually become a stronger carbon sink.”

Gower is now assessing how much carbon the trees actually took up and trying to secure funding to add another layer of complexity to his project. He wants to study a plot that is both warmed and treated with elevated levels of carbon dioxide.

“This will add a whole new set of logistical considerations,” he says. “We really need to understand how these multiple stresses interact to influence the carbon budget of the entire forest.”

A climate for learning

Tom Gower likes using undergraduates on research projects. His motivation, he admits, is selfish.
“I like to use undergrads because they often become my graduate students,” he says. “It’s a great training ground for things that can’t be taught in a classroom or even in a lab.” He employs about five a year — about 50 students since he began his work in the boreal forest. Many have gone on to do graduate work.

Dustin Bronson is one such student. He connected with Gower’s group as an undergraduate at Michigan State and later transferred to the College. He is now enrolled in the College, working on his master’s degree in forestry and spending his summers at the remote Thompson research site.

“You either love it or you hate it,” says Bronson. “I love it.”

Field research opportunities also helped Gower recruit Ingrid Van Herk. She started working with Gower as an undergraduate at a Canadian university, and then enrolled in the College as a graduate student to continue working on his project. She spent the entire summer of 2004 at Thompson, from opening the site in early May to packing up for winter in mid-November.

“I love being in the field because it’s so exciting to see a project like this first hand,” she says. “It’s
different from learning from a textbook. You can see the progress yourself.”

Gower says that he feels strongly about the value of including students in his work each summer.

“It’s an experience that lets them begin to see what science is all about and see if it’s what they want to do.”

However, it’s not always easy to work in a remote part of Canada. Some people can’t take
the isolation, he says, let alone the swarms of mosquitoes and flies.

But there are perks. Gower and his team enjoy beautiful displays of the northern lights. They can take the train to Churchill to watch polar bears and beluga whales. And they’ve seen bobcats and timber wolves near the site.

“Also, the people of Thompson have greeted us with open arms,” hey says. “We’ve tried to meet all requests to give guest lectures about our work and to involve local people whenever possible. They’re interested in what we’re learning in their own backyard.”

Science education plays a role

Gower says that educating the general public about the issues and science related to global warming is an important extension of his research.

The topic isn’t easy to understand, which is one reason he’s a strong advocate of science education — the earlier, the better. He felt the influence of good science teaching as a central Kentucky farm boy, when one of his science teachers inspired him to pursue a research career. Remembering that, he takes his role as educator very seriously.

“We scientists need to do a better job of trying to convey that [climate change] is real and the important implications it has for the health of our environment, our economy and the sustainability of the biosphere for future generations.”

He also keys into another, corollary message: The potential of individual influence is almost endless.
“We all have the potential to change our lives. Where we spend money, what transportation we use, how we dispose of waste — all of these affect levels of greenhouse gases. We’re just beginning to discover the effective strategies.”

And that, says Gower, is an example of why he feels fortunate to be part of the College.

“From the day I arrived here I have been allowed the freedom to pursue what’s of interest, what’s exciting and what’s needed. There’s also a vast number of faculty with other specialties to collaborate with and learn from — there’s hardly any university I can think of that can rival the breadth that Wisconsin offers.”