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Environment

To Save Trees From Climate Change, Researchers Try Assisted Migration

RENEE MONTAGNE, HOST:

In Canada, conservationists are performing a radical experiment to save some endangered trees from the impacts of climate change, moving them. It's called assisted migration. Scientists around the world are trying it with other plants and animals as well. Sally Aitken is a plant geneticist at the University of British Columbia. Seven years ago, she planted the seeds of a tree that was hurting as its environment warm to a place closer to its traditional habitat. She says those seeds have now grown into seedlings at a normal rate. She joined us from Vancouver. Good morning.

SALLY AITKEN: Good morning, Renee.

MONTAGNE: Tell us about the whitebark pine. That is the tree. And I gather it's endangered.

AITKEN: Yes, whitebark pine is a very special species that we find at high elevations. It's usually the uppermost tree-lined species in the West. It's involved with the grizzly bear food, it's dispersed by a single bird species, and it stabilizes snowpacks and plays many ecological roles in those environments.

MONTAGNE: So it does all those things, and yet now it is trying to survive in a warmer environment which has changed what to make it endangered.

AITKEN: Well, it's suffering from many challenges. The first is an introduced disease called white pine blister rust. The second is the mountain pine beetle. That's really expanded due to warmer winter temperatures. And the third is the effect of the warming climate on other species that are competing with it.

MONTAGNE: Seven years later, how is the whitebark pine doing in its new home, which is where?

AITKEN: So the new homes, we put them in our up to 500 miles north of the natural range. And the last time they were visited, some of those trees were doing quite well. We need to reassess them and see if they have continued to do well, survive and grow.

MONTAGNE: This would seem to be controversial partly because many scientists are very concerned about introducing species outside their environment. Are you worried that the whitebark pine could itself someday become invasive?

AITKEN: The whitebark pine, specifically, is quite unlikely to become highly invasive. It's a very slow-growing and very slow-to-reproduce tree. And it's growing in very cold environments that don't favor much growth and reproduction.

MONTAGNE: Now you mentioned a bird, and this I gather. The seeds of the whitebark pine are usually spread by this bird called a Clark's Nutcracker. What if everything goes well? Would the next step be to introduce the birds into the area where you've transplanted the trees?

AITKEN: Well, it's an interesting thing that the birds have not already moved whitebark pine farther north. So these climates, there are areas that the climate's been favorable in the past for whitebark, but it hasn't gotten there yet. And that probably is to do with the bird. I don't think we're going to be moving the birds. But if we made the decision to establish populations farther north, the birds may move into those areas and then assist with further dispersal.

MONTAGNE: Still, it is a dramatic image of the future, that is trees being helped to move.

AITKEN: It is absolutely. And trees can migrate species ranges. They've done that since the last Ice Age, maybe 100 yards a year at the fastest, but it's not fast enough to keep up with climate change. Really, the whitebark pine is one example of what we might have to do on a much larger scale, moving species farther north into these areas that they can't disperse into and establish in quickly enough.

MONTAGNE: Well, thank you very much for talking with us.

AITKEN: You're very welcome.

MONTAGNE: Sally Aitken is head of the Centre for Forest Conservation Genetics at the University of British Columbia. Transcript provided by NPR, Copyright NPR.