In Fear Of Firebugs: Helped By A Warming Planet, How The Pine Beetle Is Altering America’s Forests

by Michael Kodas, via On Earth

In a little over a decade, the largest mountain pine beetle outbreak on record (by a factor of 10) has killed more than 70,000 square miles of Rocky Mountain forests — an area the size of Washington State. From above, the infested pine trees seem color-coded: green is healthy, red is dead, and after three or four years, the dead red needles fall off, leaving behind a graveyard of bare gray bark — or, if you’re worried about wildfires, what amounts to a field of 100-foot-tall matchsticks.

Colorado, already facing the most destructive wildfire season in state history, has 3.3 million acres of beetle-killed forests to worry about. No one doubts that dead and dying trees are a potential problem, but fears that the beetle infestation will fuel larger firestorms might be premature (at least in the short term). Across the West, some 40 scientific studies have failed to produce a clear picture of how millions of beetle-killed trees will burn.

One recent paper by researches at the U.S. Forest Service and University of Idaho predicts that during the “red phase” — when trees are dead but still have rust-colored needles — severe crown fires may burn through the treetops with greater speed and intensity than they would in healthy green forests. A study last year by ecologists with the U.S. Forest Service’s Rocky Mountain Research Station showed that in beetle-infested forests, the red, dead needles ignite three times faster than their living counterparts, largely because they have 10 times less moisture and different chemistries than living, green needles.

The intensity of the crown fires in red, beetle-killed forests, the researchers predict, could also launch embers farther, thus spreading the fire faster over a greater territory. Another model shows that lower fuel moisture in the canopies of red and gray forests and dead trees that fell to the ground during and after the gray phase increased the intensity of ground fires, which allowed crown fires to erupt with less wind than they usually require. Other studies show that gray forests, in which the needles have fallen from the trees, are likely to slow down crown fires. Trees in those forests, however, have a great risk of “torching” — which means they burn individually with high, intense flames.

But other research contradicts the studies showing that beetle-killed forests are a cause for alarm.

A report released last year by the Joint Fire Science Program at the National Interagency Fire Center in Boise, Idaho, holds that neither red nor gray forests are likely to burn more severely than a green forest, largely because the death of the trees would reduce the amount of fuel in the forest canopy. The paper maintains that climate and weather factors, rather than fuel, drive most wildfires.

Climate is also behind the severity of the beetle outbreak. Without prolonged sub-zero temperatures — something most of the Rocky Mountains haven’t seen in a decade — pine beetles thrive, while trees stressed by drought and heat waves grow more susceptible to pests. In a report earlier this year, Jeffry Mitton and Scott Ferrenberg at the University of Colorado documented that, due to the warming climate, mountain pine beetles in some Colorado forests have gone from reproducing once a year to twice a year, leading to an exponential increase in the number of insects. And they’ve got more places to spread: for most of the 20th century, overeager fire suppression made forests unnaturally dense. Now diseases and pests can spread through the woods like plague through an overcrowded slum.

In the end, the risk that many firefighters fear is not in today’s red or gray forests, but in the long-dead forests of the future. At least for now, most trees are still standing. But decades from now, when the beetle-killed trees fall to the forest floor and new pines grow above them, there’s bound to be trouble, as the one-two punch of dead timber on the ground and explosive canopy fires in the fresh trees above prove doubly difficult to fight.

When I was a seasonal wildland firefighter with the U.S. Forest Service a decade ago, the firefighters I worked alongside gave little thought to this tiny pest chewing through forests. Today, when they look at entire mountains covered with dead trees, the firefighters I’ve talked with can’t help but imagine what kind of hell they would face if all that timber were to erupt into flames at once. How would they survive it, much less stop it? That’s an answer perhaps no study can give us — until it’s too late.

Michael Kodas is currently working on the book “Megafire,” which will be published by Houghton Mifflin Harcourt in 2014, and is the author of the bestselling book “High Crimes: The Fate of Everest in an Age of Greed.” This piece was originally published at OnEarth and was reprinted with permission.


3 Responses to In Fear Of Firebugs: Helped By A Warming Planet, How The Pine Beetle Is Altering America’s Forests

  1. Mike Roddy says:

    There appears to be a gag order on the relationship between clearcut logging and forest fires, something long established in the peer reviewed scientific literature:

    When you destroy a forest by logging it, local air and water temperatures go way up. This increases fire risk, made worse through evaporation and fine fuel loads.

    The Forest Service won’t talk about it, because they are also in the logging business. “Green” organizations have been coopted and worn down, with the exception of Native Forest Council.

    Industrial logging is a huge part of US carbon emissions, on many levels.

  2. The title makes no sense: firebug is a synonym for arsonist, yet the article does not mention arson.

    No evidence is presented that beetle infestations are primed for arson, or that arsonists strike along with beetles.

    This unsubstantiated handwringing over the alleged link between beetles and wildfire is getting tiresome.

  3. Lewis Cleverdon says:

    Seeing that the article was written for the Natural Resources Defense Council it seems a shame that it puts the focus on the emotional stress on firefghters rather than focussing on the resource implications.

    The latter are pretty stark. 70,000sq mls is almost 45M acres of dead forest so far, which at a modest 50Ts carbon per acre would hold about 2.25GtC (gigatonnes of carbon).
    The controversy over fire risk ignores the climate impact of that carbon now being at risk – if it is not cleared and responsibly used, it will either burn or rot and send that carbon aloft. While burning converts a fraction of the wood to a cocktail of gasses including CO2, CH4, CO, NOx, VOCs, etc, when the trunks rot the heartwood does so largely anaerobically, which greatly favours carbon’s conversion to methane. This matters because methane has around 100 times the GHG potency of CO2 over the crucial 20yr time horizon, so even a small percentage of carbon going up as methane radically raises the CO2 equivalent output [CO2e].

    Off the 2.25GtC dead so far, 3% as methane would give 17GtCO2e output; 6% would give 25.7GtCO2e; and 12% would give 43.2GtCO2e. All of which would be on America’s emissions ticket, thus making a mockery of the idea that US emissions are being reduced.

    Yet the resource need not and definitely should not be left to rot or burn. What it should be is the pump-priming resource for America’s program of carbon recovery, specifically the recovery over time of its ‘historic emissions’, with the forests’ full replanting being funded by the sale of products.

    Simple mobile charcoal retorts could convert about 70% of the wood’s carbon to charcoal, with about 28% of the wood’s energy potential being released as crude woodgas which is readily converted to methanol by small modular stills.

    This would not only provide an unprecedented scale of rural employment, but also sufficient charcoal for biochar production to treat around 160 million acres at 10Ts/acre, thereby both raising soil fertility and also moisture moderation. In addition it would launch a potentially highly sustainable methanol silvifuel industry (as distinct from agri-fuels) on a very substantial scale. Both of these technologies are of major international significance and replicability, and the US would do very well to set the lead on them.

    So where are the green entrepreneurs seeking major innovative necessary enterprises,
    and the progressive politicians seeking mass employment options and the raising of US international respect,
    and the farm lobby seeking improved drought and flood resistance of the farmlands,
    and the manufacturers seeking new equipment mass-production options for home sales and export,
    and the conservationists seeking the restoration of the forests and the avoidance of this massive feedback loop on global warming ?

    Since the NRDC is evidently blind to this need of a convening entity, what other organization is going to fulfill it ?