Beetle-infested forest becomes carbon source

[brianidaho]

The Spokesman-Review.com


Beetle-infested forest becomes carbon source
Decomposing trees release gas



Catherine Tsai
Associated Press
April 24, 2008

DENVER – An outbreak of mountain pine beetles in British Columbia is doing more than destroying millions of trees: By 2020, the beetles will have done so much damage that the forest is expected to release more carbon dioxide than it absorbs, according to new research.

The study, led by Werner Kurz of the Canadian Forest Service, estimates that over 21 years trees killed by the beetle outbreak could release 990 megatons of carbon dioxide into the atmosphere – roughly equivalent to five years of emissions from Canada's transportation sector.

The outbreak has affected about 33 million acres, or about 51,562 square miles, of lodgepole pines. Bark beetles also have killed huge swaths of pines in the western United States, including about 2,300 square miles of trees in Colorado.

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"When trees are killed, they no longer are able to take carbon from the atmosphere. Then when dead trees start to decompose, that releases carbon dioxide into the atmosphere," Kurz said.

That could exacerbate global warming that contributed to the outbreaks in the first place. Warmer temperatures have allowed beetles to survive farther north and at higher elevations.

"This is the kind of feedback we're all very worried about in the carbon cycle – a warming planet leading to, in this case, an insect outbreak that increases carbon dioxide into the atmosphere, which can increase warming," said Andy Jacobson, a carbon cycle scientist for the National Oceanic and Atmospheric Administration in Boulder, Colo.

Boreal forests in Canada generally have been steady "carbon sinks," absorbing more carbon dioxide than they emit. Kurz's team expects the forest it studied to recover, but says that even by 2020 it may not be the carbon sink it previously was.

"This long-term effect, personally I find it frightening," said Jacobson, who was not involved in the study, which is being published this week in the journal Nature.

Using computer models, Kurz's team estimated that the maximum annual beetle impact in the study area in south-central British Columbia was 20 megatons of carbon. Forest fires in all of Canada produce an average of 27 megatons a year.

Kurz's team says the effect of pine beetles and other insects is significant and should be included in models of how much atmospheric carbon the world's forests can store.

"Many other insects also impact the forest carbon cycle," Kurz said. While outbreaks of other insects such as spruce beetles may be much smaller, their cumulative effect is significant, he said.

"If events such as this occur in other geographic parts of the world, then they really ought to be accounted for," Kurz said.

[screener]

There are tenders out in BC for the use of all the beetle killed pine to be used as fuel to generate electricity. if the methane etc. is being released anyway I guess it's better to be using it this way thatn burning other fuels to accomplish the same generation.

The trouble I foresee is that down the road when existing kill has been used up, the beetles are back to normal, knock on wood, and all that investment in wood fired generation is sitting there, there will be a hue and cry for more hewing of new forest to meet the demand. The other angle of this is that fertilizer in the forest has generally come from decomposing trees. If we take those out of and burn them, our next generation of trees take that much longer to get established.

[brianidaho]

I think a large part of the problem with these forests is a program of active fire supression, combined with little or no management of the forests. In many of our Western forests, historically, low intensitity fires would go through every 5-10 years and burn out small fuels and smaller trees, effectively thinning the forests, resulting in stronger, more insect and disease resistant trees. A century of aggressive fire suppression has resulted in overcrowded stands filled with stunted, unhealthy trees. At this point, there will not be a "low intensity" fire, only a catastrophic "running crown" fire that destroys everything in it's path. It should be noted that these overcrowded, unhealthy stands are very poor habitat for wildlife, in that they do not provide suitable food sources.

One item I'm a little "fuzzy" about is that these specifically are lodgepole pine forests. IIRC, they are a somewhat unique tree, in that they require fire to cause the cones to release seeds. I seem to recall reading that they typically would have matured, burned and died over a fair sized area, natural regeneration would result in stands of similarily aged timber, repeating the cycle. This is opposed to Ponderosa Pine forests for example, which may well have more of a mix of tree ages and maturities. I hope a forester chimes in hear with some more insight. Having said this, I have seen considerable natural regeneration of lodgepole pine in forests that have not burned (including my own property).

Given our sensitivity to air polution and value of the resource, indiscriminate use of fire as a means of controlling forests isn't practical any more. Active management, including using logging as a tool to thin overgrown stands and perhaps replanting with species most suitable for the site, can help. Once thinning has taken place, perhaps fire can be used as a means of keeping the understory clear.

Using the dead biomass as a fuel for power generation is an interesting concept. It would be interesting to see the economics involved, to know if the cost of harvesting and transporting the dead timber makes them cost effective as a fuel source-I would hope that it would. I'm not sure how much you would have to worry about running out of fuel, thinning and management of the forests is a constant, recurring issue. Canada, and to a lesser extent the Western US have large forests Unfortunately many of them in the US, particularly those on National Forest lands, are in a similar state to these Canadian forests. Active forest management came pretty much to a halt in the mid-90s under the Clinton administration...forest health has paid a price. In my state, some 70% of the land is owned by the Federal government, yet only 10% of the timber harvest in the state is from Federal property. What the Mountain Pine beattle hasn't gotten (lodgepole, which do well here), the White Fir engraver beatle, Douglas Fir bark beatle and root disease are impacting. I've been dealing with these issues on a small scale on my own property.

I'm not condoning some of the past practices of the forest products industry, especially indiscriminate clear cutting. However, many private forests are much healthier, much nicer looking and provide a better home to wildlife than our often neglected national forests. Forestry techniques have evolved to where harvest can occur and leave a nice looking, thinned forest. Unfortunately, virtually every timber sale in the West is tied up in lawsuits these days. Things are getting worse, the latest attack in the form of the "Roadless Initiative" pretty well "locks up" about half the national forest in my state...it will be an interesting fire season for the next few years.

Bri