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 NRRI Climate Change Research

Local warming, not global warming, has our attention

NRRI scientists have been actively engaged in studying the impacts of climate change for 20 years. But today’s climate for these discussions is much more comfortable.

A computer model simulates biological processes like photosynthesis and carbon allocation.

That wasn’t the case in the mid-1980s when forest ecologist John Pastor came to NRRI to study how a predicted warmer climate would affect tree growth. At that time, no one else was doing research to predict what warmer, drier conditions would do to Minnesota’s wood resources—and the scenario from his computer model wasn’t exactly good news for industries that depend on those resources.

“Changes in temperature and precipitation mean changes to the forest,” Pastor explained. “The sandy soils up north just can’t hold enough water to compensate. And on clay soils that can hold enough water, there will still be forests, they’ll just be different forests.”

The climate model predictions for Minnesota are now widely publicized and generally accepted. Over the next century, scientists expect a five to 10 degree Fahrenheit temperature increase, and increased extreme storm events. More evaporation and transpiration will cause drier soils. Along with these changes will come a domino effect of stresses on everything animal and vegetable.

From the early forest sustainability research NRRI has built a strong research portfolio, lending its environmental expertise and industry focus to study climate impacts on water quality, amphibians, birds and mammals.

Joining forces with the University community

NRRI’s climate change research fits nicely with the University of Minnesota’s goals for its new Institute on the Environment (IonE). NRRI aquatic scientist and IonE founding fellow Lucinda Johnson began her research on climate change in 2001 when a colleague recommended her as an author on a report that has become the reference manual for impacts to the upper Midwest. “Confronting Climate Change in the Great Lakes Region” was published in April 2003 by the Ecological Society of America and the Union of Concerned Scientists. As one of 13 authors, Johnson’s role was to study the impacts on aquatic ecosystems.

The background knowledge from that project led to funding from the Legislative-Citizens Commission on Minnesota Resources to pull together data that shows readily apparent signs of climate change in Minnesota. NRRI scientists are leading a team that is looking at data already available on climate and responses to changes in water quality and levels, aquatic ecosystems, fish and plants.

Johnson is organizing the layers of information into a computer landscape that helps scientists understand how all those biological elements interact in response to a warmer, drier climate. Other NRRI aquatic ecologists are helping to assemble and analyze water quality and biological records of Minnesota lakes and their relationships to climate, ice-out and land use trends.

“Climate change will not take place in a vacuum,” said Johnson. “We already have many other stressors on our ecosystems. Ethanol production, for example, is up because we’re concerned about the scarcity of oil and we’re trying to reduce carbon dioxide emissions, but there are big concerns about growing more corn because corn production depletes soils and causes water pollution. Facilities that produce ethanol also use scarce ground water resources.”
Johnson thinks NRRI’s role as an advocate for both environmental sustainability and industry puts it in a unique position to help both sides meet in the middle with solid information.

“Will the forests be sustainable? Will the trees stay healthy? Will we have enough clean water for the future? Those questions affect us all,” said Johnson.
Seeing the forest for the trees

While Pastor modeled the larger forest landscape back in the 80s, NRRI forest ecologist George Host came on board and zeroed in on computer models of individual trees and their response to increased ozone, temperature and carbon dioxide. Ozone, like carbon dioxide, is a greenhouse gas that contributes to climate change, but in the lower atmosphere affects both human health and plant life.

“There’s a lot of biology behind this technology,” Host explained. “The computer model simulates biological processes like photosynthesis and carbon allocation. How does the tree produce food for itself and how does it grow?”

Host continues this research with a patch of “virtual” trees, applying “virtual” climates, varying the conditions and watching how the trees respond. He says this modeling approach complements scientific experiments in the field. Now he’s applying the model across the Midwest for the U.S. Forest Service to predict where the forest might lose the most productivity based on future scenarios.

“We’re trying to predict the tree’s productivity loss or gain resulting from climate change,” said Host. “Increased carbon dioxide tends to increase plant growth, but ozone is an impairment. Do those two balance each other out?”

Peatlands prove their worth

By the 1990s, Pastor’s work evolved to peatlands and their role in the global carbon cycle. Minnesota has some 7.5 million acres of this type of wetland and he knew they were valuable carbon storehouses. Funding from NASA allowed Pastor and his colleagues to study how much greenhouse gases are produced and released by peatlands. This research was the first systematic measurement of greenhouse gases from peatlands in Minnesota.

By 1993 the National Science Foundation provided funds to expand the research. What happens to peatlands when climate is warmer and drier?
NRRI’s Fens Research facility—a 435 acre site located in the heart of a very large peatland complex—was set up with 60, circular bog and fen mesocosms (small ecosystems) weighing about one ton each. Each mesocosm was subjected to varying temperatures and water levels.

The results are proving to be valuable. Pastor recently received a call from Governor Pawlenty’s office asking what can be done to prevent carbon from being released from peatlands.

“I told them, just keep the water table high, because when it drops the peat decomposes and collapses, releasing carbon,” said Pastor. “A lot of peatlands were drained for farming in the 1930s and I would say, let the water table rise where possible. Any ditches that aren’t already plugged up should be.”

Frogs facing hard times

Of course, all wetlands—and the critters that live in them—will be affected by warmer and drier conditions. NRRI research on leopard frogs living in the shallow wetlands in southern Minnesota suggests that climate change, added to other stressors like agricultural chemicals, could tip the scale.

Tadpoles need water for at least 90 days to develop and then survive best if the pond dries up periodically—it clears the wetland of disease-causing microbes and predators. In warmer conditions, seasonal wetlands may not hold water long enough for breeding and the deeper wetlands that hold water all year round tend to support more predators such as waterfowl and fish. Still, the deeper, semi-permanent wetlands will be important refuges if seasonal wetlands dry up more frequently. The proximity of appropriate wetlands is critical and will need to be considered when decisions are made about protecting and restoring wetlands in the future.

“Frogs can wander from wetland to wetland, but are fairly limited in how far they can travel,” said NRRI eco-toxicologist Pat Schoff. “Roads and urban areas also create barriers to movement. There will just be a much lower number of available breeding areas and more species competing for fewer wetlands.”
Unfortunately for the frogs—and all biota—climate change is just one of many stressors that threaten their existence. Invasive species, chemicals, development and habitat degradation have made what Schoff calls “a poorly tended garden.”

“We’ve altered this landscape so much that the existence of some of our most familiar species may be threatened,” said Schoff. “What would the extinction of leopard frogs mean? We know they’re an important part of the wetland food chain, but we don’t know what it would be like without them—how many insects do they eat? Who depends on them for food? How do you quantify the value of a species?”

Woodland animals on the move

Wildlife have adapted over millennia in northern Minnesota’s cold, snowy climate. Species such as moose, Canada lynx, rock vole and many boreal forest bird species will likely decrease or disappear from the area entirely, according to NRRI center director Jerry Niemi.

“We’re seeing southern species, like the opossum, raccoon, coyote and red-bellied woodpecker ranging further and further north,” Niemi said. “And increased temperatures and changes in precipitation patterns will also negatively impact our northern waterfowl populations.”

Each passing year adds more greenhouse gases to the atmosphere, escalating us up the graphs that project the future warming of the planet. But each year also adds more data gathered by scientists.

“When I first started working with climate change, I was surprised at how little data there was for actual experimental studies on the impact of potential climate change,” said Johnson. “Our role at NRRI is adding to, and interpreting, the data that can help decision-makers—industry or resource managers—plan for the future.”.

by June Kallestad


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