Microbiologist Tom DeLuca studies 'the tiny' to find big answers on climate change

DeLuca talks to a group during the field project. Courtesy Tom DeLuca.

Listen to ecologist Dr. Tom DeLuca talk about his research trips to the remote area of northern Sweden and you’ll be treated to an ecological mystery story.

Birch forests once filled an open valley in the mountains between Sweden and Norway just north of the Arctic Circle, but sometime around 1000 years ago the trees disappeared.

All that remains today is an open vista and the collapse of an ecosystem, says Dr. Tom DeLuca Senior Forest Ecologist with The Wilderness Society.

Wild Science

Welcome to Wild Science, our newest feature highlighting Wilderness Society scientists and their research. We start with Forest Ecologist Dr. Tom DeLuca as he unravels mysteries of the forest.

As a soil microbiologist, DeLuca investigates relationships among tiny members of the forest community to understand how interfering with those relationships can impact the larger forest and landscape.

As part of a team of international scientists determined to understand what the landscape once looked like and why it failed, DeLuca has helped determine a critical piece of the riddle.

The story starts with a suspected period of intense climate change. Then the plot thickens with the ancient Sámi people, who likely over-exploited the birch. After they depleted the birch, the Sámi moved on to using up the juniper. That’s when things really went awry.

Juniper, DeLuca explains, may have been a keystone species in the ecosystem. Young birch saplings that grow up within juniper clumps are protected from the hungry mouths of reindeer, but just as important, the juniper also provide cover and nutrients for the feather moss. That’s where DeLuca’s work comes in.

What DeLuca’s research demonstrated is that the feather mosses are a critical source of nitrogen in these northern ecosystems that lack legumes. Once these mosses were compromised, the ecosystem could no longer thrive.

The point of this lesson, says DeLuca, is that human stressors on the landscape will most certainly add to the unpredictability of climate change.

“We can’t predict what’s going to happen with climate change, but we can predict that when human stressors, like over-harvesting of forests and off-roading, are combined with a changing climate, it is going to result in systems being turned on their heads,” he said.

Forests and climate change

Back home in Bozeman, Mont., where DeLuca spends most of his time, the ecologist is helping shed light on the micro-relationships in our own forests, and more specifically their role in mitigating global warming.

One debate that DeLuca has weighed in on is whether old growth forests are better for climate change mitigation than second growth forests.

While some say younger trees are better for carbon sequestration because they absorb carbon faster than older trees, DeLuca along with University of Montana graduate student Sarah Bisbing, recently completed a study of forest carbon levels that demonstrates that sometimes older is better.

In this 2007/2008 study of inland Northwest old growth forests in western Montana, DeLuca and Bisbing compared trees, downed wood, shrubs, forest floor, and soil in old growth forests with those of second growth forests harvested in the 1960s. Through the investigation, the researchers demonstrated that the old growth stands stored approximately three times more carbon than the second growth stands in a neighboring area.

The upshot is that pristine forests should be protected, DeLuca said.

“We’re not saying that everything must be old-growth, but anything that is already intact should be left alone,” he said.

DeLuca has also led other Wilderness Society scientists in studying charcoal as a carbon storage byproduct of forest fires. What they’re learning also has deep implications for forest management and climate change.

In their 2008 paper , DeLuca and co-author Greg Aplet reported that the carbon stored as charcoal after a wildfire has a far greater longevity than that stored in woody material, a finding that could have great implications for forest management.

“In fact, we’re talking about tens of thousands of years — or millions if the charcoal makes its way to a marine environment,” he said.

DeLuca’s study determined that intact forests, even when they burn, store more carbon and in a form that lasts vastly longer than that stored in forests that are logged.

The research is nicely complemented by another Wilderness Society study that shows much of the carbon in forests subject to timber harvest are released in the logging, transportation and milling process and further, that the durable woody products actually have a surprisingly short residence time.

These studies demonstrate that from a climate change perspective logging and thinning of intact forests to prevent fire-related release of carbon can actually contribute to a greater net release of carbon dioxide into the atmosphere in the long term.

Click here to learn more about Tom DeLuca’s work.

photos:
DeLuca leading group to field project. Courtesy Tom DeLuca.
DeLuca conducting field research. Courtesy Tom DeLuca.

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