Radio Script
2000

 

Northern white spruce forests could change dramatically, according to evidence found in tree cores being studied by graduate student Valerie Barber at the University of Alaska Fairbanks. Photo by Doug Schneider, Alaska Sea Grant.

 
White Spruce Trouble
__________________

Listen on RealAudio

Don't have RealAudio player? Download free software.

INTRO: It isn't every day that a scientist gets his or her research into the prestigious journal Nature. It's even more rare when a graduate student accomplishes such a feat. As Doug Schneider reports in this week's Arctic Science Journeys Radio, University of Alaska Fairbanks student Valerie Barber's research on Alaska white spruce is expected to change the way scientists predict the impact of global climate change.

STORY: Valerie Barber says she didn't hold out much hope for actually getting her research published in the journal Nature.

BARBER: "I was shocked."

Yet the unlikely happened this week when the distinguished science magazine published her research on the impact of a warmer Arctic climate on white spruce trees in Interior Alaska's upland boreal forests.

Barber, together with colleagues Drs. Glenn Juday and Bruce Finney of the University of Alaska Fairbanks, analyzed tree ring data to measure the growth of white spruce trees. Their findings contradict the widely held scientific belief that a warmer Arctic climate should spur rapid plant growth. The data suggests that upland white spruce trees aren't benefiting from a warmer climate.

BARBER: "That's actually why Nature picked it up as a matter of fact. Because most of the global climate models predict that with increased warming and increased CO₂ (carbon dioxide), the plants will be growing better. And so what we're seeing in Interior Alaska are rising temperatures, and then if you look at precipitation, that's not going up at all. In some places there's a slight decline. The trees are becoming moisture stressed. What we see with our trees is actually a negative correlation between growth and temperature. So, warmer temperatures, less growth."

Barber says that rather than spur growth, the warming trend has made Interior Alaska more arid. And with less moisture, the trees just can't take in enough carbon dioxide to grow.

BARBER: "So what's happening is that the stomates in the tree open and close during the day to let CO₂ in for photosynthesis. And they also respire, losing water and putting out oxygen, etc. But if it's really hot and dry, the stomates won't open as much. It's almost like they're gulping air."

Dr. Charles David Keeling, a pioneer in the study of global climate change at Scripps Institution of Oceanography in California, says the researchers' findings shed new light on the impacts of climate change on the Arctic.

KEELING: "Well, this is even saying that some areas of the Arctic will dry out, and so the tress won't even grow as well. If it's getting warmer and if it continues to get warmer, then the question is whether it's healthful or not healthful. I think it's inevitable that if the climate changes, that some plants will benefit and others won't."

Researchers have long thought that the world's vast northern boreal forests would act as a kind of carbon sink—plants would absorb CO₂ and store it as plant tissue—thus helping to lessen the effects of warming. Keeling says Barber's research calls those assumptions into question.

KEELING: "The idea that forests are going to sequester carbon because it gets warmer by growing faster probably is wrong for the higher latitudes. It's wrong for very good reasons. There's a lot of organic carbon stored in the cold soils. And if the soils dry out and warm up, then the likelihood is that carbon is going to be released."

What's more, if the warming trend continues, Barber says the boreal forests that exist now could change dramatically in the years to come.

BARBER: "One of the things that we've surmised is that if the white spruce can no longer grow here, we're going to be seeing a kind of change. We already have aspen trees here, but we'll be seeing more of an aspen parkland type of vegetation."

Barber hopes her research will help produce more accurate models of climate change, especially as those changes affect the Arctic.

BARBER: "When they do their models they need to take this into account and start changing some of their predictions."

OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.

PDF text of Valerie Barber's research published by the journal Nature

Thanks to the following individuals for help preparing this script:

Valerie Barber
University of Alaska Fairbanks
School of Fisheries and Ocean Sciences
Institute of Marine Science
Fairbanks, AK 99775
Phone 907-474-7899
Email: barber@ims.uaf.edu

Dr. Charles David Keeling
Scripps Institution of Oceanography
University of California San Diego
San Diego, CA
Phone: 858-534-4230
Email: cdkeeling@ucsd.edu

Dr. Glenn Juday
University of Alaska Fairbanks
Fairbanks, Alaska 99775
Phone: 907-474-6717
Email: gjuday@lter.alaska.edu