Pine Forests Destroyed by Beetle Takeover Canadian forests are being hit hard by an outbreak of the mountain pine beetle. Though the beetles are small — less than 1/3 of an inch long — they're hungry, and bore through the wood of a variety of pine tree species. Ecologists are worried that the death of so many trees will have a significant impact on the carbon balance in North America.
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Pine Forests Destroyed by Beetle Takeover

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Pine Forests Destroyed by Beetle Takeover

Pine Forests Destroyed by Beetle Takeover

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IRA FLATOW, host:

This is Talk of the Nation, Science Friday. I'm Ira Flatow. A bit later, we'll be talking about lab grown meat, and the link between dinosaurs and birds. But first, hungry pine beetles in Western Canada, have decimated millions of acres of mature pine forest in British Columbia. But scientists are worried about more than just losing an old growth forest. The outbreak is actually threatening the balance of carbon in the region. That's because the northern forests are considered a climate sink, a carbon sponge, whose trees soak up more carbon than they give off. But as the pine beetle outbreak kills more and more trees, which release carbon as they decay, that balance is shifting. And what's now a carbon sink could become a carbon source in just a few years. Could the same thing be happening in the lower 48 sometime, where the pine beetle also has a hold? Joining me now to talk about the pine beetle outbreak and how it's changing the planet's carbon balance, research published in this week's issue of the journal Nature, is my guest Werner Kurz, senior research scientist at the Canadian Forest Service of Natural Resources, Canada in Victoria, British Columbia.

Welcome to the program, Dr. Kurz.

Dr. WERNER KURZ (Senior Research Scientist, Canadian Forest Service): Hello and thank you for the invitation.

FLATOW: Tell us about this balance, and why it might be upset?

Dr. KURZ: When trees grow, they remove carbon dioxide from the atmosphere and store it in wood, about 50 percent of the dry weight of wood is carbon. And when trees die and start to decompose or burn in wild fires, that carbon dioxide is released back into the atmosphere. So what we are trying to understand with our research is what the net balance of carbon emissions and carbon removals by forests is, and how they contribute to the global carbon cycle.

FLATOW: And the idea here is that the pine beetle is quickly chewing its way through the forest and upsetting that balance.

Dr. KURZ: Yes, what is happening in British Columbia is that we have an outbreak of an endemic pest, a pest native to the pine forests of western North America, that is of unprecedented proportion. We have now an area of about 40 million acres of forest that are affected by the pine beetle. And throughout these forest, the beetle various degrees of mortality from a few trees per acre killed to literally 80 or 90 percent of the mature pine killed by the beetle.

FLATOW: My goodness. Why suddenly, this tremendous growth spur?

Dr. KURZ: What has been happening is really the combination of a number of factors starting with forest fires that occurred at the beginning of the 20th century, 1882 to 1920s affected wide spread areas of western North America. In fact, Smokey the Bear and other initiatives to fight forest fires were initiated around those days. And these forest that regenerated naturally from the wild fires are now 80, 100, 140 years old. As a result of fire suppression throughout much of this time, they have reached large tracts of mature pine, which normally would not have occurred had we more fires or logging occurring in these areas.

And so, the beetle finds an overabundance of food source. And the second factor is that climate warming is influencing the beetles' population dynamics. Warmer summers have allowed populations to grow about average, and mild winters, we have not had the minus 40 degrees centigrade killing temperatures that bring about beetle death in the over-wintering beetles in the stems. And so these two climate change factors together have allowed the beetle population to expand northward and into higher elevations in these pine forests. And cover an ever increasing area. It's been literally an exponential growth in the beetle population.

FLATOW: Is there anything you can do about it?

Dr. KURZ: Very little unfortunately. At the early stages of a pine beetle outbreak, you can cut down a tree that was infested by the beetle and burn it so that the next generation of beetles cannot emerge from the tree, but these beetles spend most of their life cycle inside the trees, under the bark. And they only emerge in late July to early August, in a two-to-three-week period to fly to the next forest stand, and start boring into the trees there to initiate the next generation of beetles. And so, there is a very narrow - there is no mechanism by which you can control the beetle, other than through cutting down the trees in which they live. And basically, kill the brood by burning them.

FLATOW: And what is it - is it the beetle eating the trees or something else is happening?

Dr. KURZ: Well, what happens is that the beetles bore under bark, and into the phloem of the tree. And they bring with them a fungus, and it's actually the fungus that clogs the water-guiding tissue to the foliage. And they basically plug the water supply, if you want, to the trees. The trees dry out and in a matter of a few months, they go from green to red, to eventually a gray when the needles fall off, and the trees are completely dead. But basically, the tree that beetles overwhelm - the beetle in a matter of a few months, and the tree is dead.

FLATOW: Is this the same pine beetle that is infesting the Rocky Mountains in the U.S?

Dr. KURZ: Absolutely. Yup, it's the same beetle that basically spans from California northward all the way up to British Columbia. There are multiple beetles out there, of course. But this is the one that is the Western pine beetle - Western mountain pine beetle.

FLATOW: And why is it so much more potent up there, than it is down there in the Rocky Mountains?

Dr. KURZ: Well I think, the main reason is just this very large abundance of mature pines. And in addition to that, the favorable climate and the ability to expand into areas in which it has historically not been operating.

FLATOW: Is it possible to replant more trees that could make up, and you know, suck out more CO2?

Dr. KURZ: Yeah, well, first I think we need to understand what happens is - as the beetle does its thing, so to speak. The reason we have the big impact on the carbon cycle is because the beetle, in killing the trees, stops photosynthesis. So the first important function of the forest, which is to absorb carbon dioxide from the atmosphere is interrupted. And then second, all the carbon that has accumulated in these forests, in these trees, is now available for decomposition by bacteria and other soil organisms. And in doing so, the carbon that has accumulated over the lifetime of the tree will now be released back into the atmosphere over the next years or decades. So, one of the things that we of course, can then do, in order to try to fend off some of this impact of the beetle on the climate system is to try to accelerate the reestablishment of forest through planting and other supracultural(ph) measures. That will allow us to get this carbon sink working again, as quickly as possible.

FLATOW: If there any, would it be better to log the diseased trees out of there, and maybe keep the carbons sequestered in them somehow?

Dr. KURZ: Well that's - that's the other sort of mitigation option that we are exploring, and trying to quantify. Basically, with the trees decaying and the carbon being released to the atmosphere, the carbon is basically fed back into the atmosphere without benefit to society, without direct benefit to society. So one question is if through salvage logging, we can take that wood in the first few years after the insect attack and use it for construction purposes or other mechanisms by which the wood retains its carbon, the carbon in the buildings or other structures.

So that is one mechanism. And the other mechanism which we are discussing very actively is the question of salvage logging for bio-energy. Because if we harvest the trees, if we use the energy contained in the wood to offset fossil carbon, then the carbon that would otherwise be emitted from fossil fuels can remain in the ground, and the energy is derived from the wood bio-mass. And the nice thing about that type of bio-mass, which is already out there and dead, killed by the beetle or by wildfires, or other impacts of climate change, is that it is not competing with human food supply.

There is a lot of discussion right now about bio-fuels and bio-energy, and we are witnessing the global impacts of increased use of biofuels from agricultural products on food prices and food production.

FLATOW: So if you could take those logs out and chip them or whatever, and then turn them into some sort of feed stock for alcohol, cellulosic(ph) alcohol, something like that.

Dr. KURZ: You could start even simpler. You could use them simply as a fuel in boilers or burners to generate steam or you can process it to varying degrees of sophistication from gasification to cellulosic ethanol to just simple wood pellets. In fact, there are plants in British Columbia now that are producing wood pellets that are being shipped to Europe, for example, to help them there meet their mandated proportion of renewal energy that they have to use in their energy portfolio.

FLATOW: When do you make that decision, about what you are going to do with it?

Dr. KURZ: Well, I think some of it is already occurring. The question is, is there merit in increasing the rates of salvage logging, and that is a dialogue that will depend on the interest of many stake holders. As you can appreciate salvage logging is not without environmental impacts, and we need to consider biodiversity. We need to consider wildlife habitat. We need to consider many ecological factors as well. And so we're by no means advocating that you know, salvage logging of every dead tree out there. But on the other hand, we have never before been confronted with such an enormous volume, and we are talking literally probably close to a billion cubic meters of wood by the time this is all said and done.

So there is an enormous of wood that is out there decaying. And at least a proportion of that could suitably and appropriately use for bio energy. The question remains, how much, and at what cost. I mean there are a lot of economic factors involved here but you know, given 200 dollars, 110, or so dollars a barrel of oil and rising, everything is changing.

FLATOW: Quick call. Michelle (ph) in Charlotte, North Carolina. Quickly.

MICHELLE (Caller): Hello?

FLATOW: Hi there. Quickly.

MICHELLE: Hi. Yes. Is there a pest that, like it is a - that would eat these beetles?

Dr. KURZ: That is a very good question and is some insect systems, that is in case, indeed the case how they get controlled. There are predators, if you want, that affect them. But in the mountain pine beetle, there is nothing that would keep up with the population.

FLATOW: And you never know what would happen if you introduced those pests.

Dr. KURZ: We do not want to go there.

(Soundbite of laughter)

Dr. KURZ: There are too many examples of introduced pests that have created new problems. So no, there is no, no active thought about introducing a pest to deal with the mountain pine beetle. It would be a bad idea.

FLATOW: Yes. Let us just see what happens and with great interest. Thank you very much for taking time to be with us.

Dr. KURZ: You are very welcome.

FLATOW: Werner Kurtz is a senior research scientist in the Canadian Forest Service, and Natural Resources Canada in Victoria, British Columbia. We are going to take a short break, and when we come back, switch gears, and talk about synthetic - could you call it synthetic, made in the laboratory, laboratory tissue-raised meat, well you can come up with your own, you know, we will try to name it ourselves, right after this break. Meat, laboratory meat. How about that? We have something better. Stay with us. We will be right back. I'm Ira Flatow. This is Talk of the Nation, Science Friday from NPR News.

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