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Fire Chronicle #17
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Laura McCarthy, Forest Trust
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Mar 24, 2003 11:35 PST
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FIRE CHRONICLE: Stories of the National Fire Plan
Number 17
March 24, 2003
BARK BEETLES HEIGHTEN WILDFIRE CONCERNS
Bark beetle infestations in many different parts of the West have led
policy-makers to seek action that will prevent further outbreaks and the
increased fire hazard that presumably results. For example, the Bush
administration recently proposed a categorical exclusion under the
National Environmental Policy Act to make it easier for foresters to
remove trees to control the spread of insects and disease. Newly
proposed legislation in the House of Representatives (H.R. 387) included
fire-insect interactions among the reasons for increased thinning.
The hypothesis that insect-caused mortality increases fire risk has been
around for almost a century. For example, a 1909 USDA Bureau of
Entomology publication suggested that insect-caused mortality would
increase the likelihood of subsequent fire (Hopkins 1909). In recent
years researchers have predicted that wildfires are likely to be larger
and more intense because of increased fuel loads and density after
epidemic insect outbreaks (Agee 1993, Harvey 1994).
A newly published article in Ecology presents findings that do “not
support the long-standing notion that insect-caused mortality increases
fire risk, which is also an important consideration in modern forest
management following insect outbreaks” (Bebi et al. 2003). The study
examined fire and spruce beetle interactions in Colorado subalpine
forests using data from an 1879 fire, a 1940 spruce beetle outbreak, and
fires from 1950-1990. The most interesting finding is that the density
of lightning-ignited fires was no higher in stands affected by the 1940
beetle outbreak than in nearby stands that were not affected. The
authors found that despite the increase in dead fine fuels resulting
from the 1940 beetle outbreak, fire density did not increase. The
authors noted that increase in fire risk usually lasts only 2-3 years
after an outbreak – that is, from the time of the outbreak until the
dead needles fall and decay. The density of fires following a spruce
beetle infestation will increase, they hypothesize, only if the
infestation is followed by extreme drought within those 2-3 years.
Scientists have also found that fire and insect disturbances have a
synergistic affect on many forest characteristics, including succession,
nutrient cycling, plant composition and species diversity (McCollough et
al. 1998). For example, forests in the west depend on insect and fire
decomposition processes to regulate nutrients (Harvey 1994). Bebi and
co-authors note, however, that the interactions between different
disturbance types have only rarely been quantitatively investigated.
Very few studies have tested for the effects of mortality caused by
insects on subsequent fire hazard because, according to co-author Tom
Veblen, “it is hard to control for confounding influences like weather
variation.”
Management for Bark Beetle and Fire Risk Reduction
The current drought conditions in the Southwest and growing populations
of four species of bark beetles have forest managers worried. The
Administration’s categorical exclusion would allow them to thin up to
250 acres of healthy trees to restore their vigor and possibly to
improve their resistance to beetles without taking months for an
environmental review. Yet thinning healthy forests could worsen
beetle-induced mortality if the slash from thinning is not quickly
removed and is left on site to cure for prescribed burning.
Orlando Romero, a Forest Service forester for 31 years, has observed
several sites on Rowe Mesa in the Santa Fe National Forest in New Mexico
where beetles were attracted to stands that were thinned and that had
green slash on the ground. He has seen several stands that were healthy
last summer become infested with beetles after being thinned for
hazardous fuel reduction, resulting in insect spread to adjacent
untreated stands. In the sites Romero observed, the slash was piled for
burning or lopped and scattered for broadcast burning.
Romero’s observations are echoed in the March “Sky Islands Forester”
newsletter of the Society of American Foresters (Wilcox 2003). In this
newsletter, foresters from the Apache-Sitgraves National Forest caution
that, “the presence of fresh slash and chipped material can attract bark
beetles,” and suggest that the timing of thinning during a beetle
epidemic is critical.
Conclusion
Additional research investigating the complex interaction between bark
beetles and wildfires is needed. In the meantime, forest restoration
treatments will be implemented and forest managers and landowners will
need to be wary of actions that inadvertently increase the occurrence
and extent of beetle infestations. Policy makers should be advised that
fire-insect interactions are complex and only partially understood by
scientists, and that current management protocols have, in some places,
had the unintended consequence of spreading insects.
By examining the old fire suppression policy we have learned that part
of fire’s role is to clean out accumulated forest fuels. Likewise, we
will certainly learn more about the role of insects in the future. We
should be careful to preserve our options before we implement a
widespread policy of thinning healthy trees to slow beetle infestations.
CITATIONS
Agee, J.K. 1993. Fire Ecology of Pacific Northwest forests. Island
Press, Covalo, CA.
Bebi, P., D. Kulakowski, and T.T. Veblen. 2003. Interactions between
fire and spruce beetles in a subalpine Rocky Mountain forest landscape.
Ecology 84(2): 362-371. Ecological Society of America.
Harvey, A.E. 1994. Integrated roles for insects, diseases and
decomposers in fire dominated forests of the Inland Western United
States: past, present and future forest health. Journal of Sustainable
Forestry 2(1/2): 211-220.
Hopkins, A.D. 1909. Practical information on the Scolytid beetles of
North American forests. USDA Bureau of Entomology Bulletin 83. US GPO,
Washington, D.C.
McCollough, D.G., R.A. Werner, and D. Newman. 1998. Fire and insects in
northern and boreal forest ecosystems of North America. Annual Review of
Entomology 43:107-127.
Veblen, T.T. 2003. Personal communication via email.
Wilcox, Craig, ed. 2003. Sky Island Forester. Newsletter of the
Southwestern Section of the Society of American Foresters. March 3,
2003. Pima, AZ.
FIRE CHRONICLE is edited by the Forest Trust and written by Laura Falk
McCarthy, Forest Protection Program Director. The Forest Trust welcomes
your comments, stories, and observations about how the National Fire
Plan is being implemented (just send a reply message and it will go to
the list moderator). To subscribe to FIRE CHRONICLE go to
http://www.topica.com/lists/firechronicles/ or send an email message to
lau-@theforesttrust.org.
PAST ISSUES OF FIRE CHRONICLE can be downloaded from
http://www.theforesttrust/forest_protection.html#fire
1. 2002 Fire Plan Appropriations will Benefit from 2001 Experience
2. Wildland-Urban Interface Definition a Barrier to Accountability
3. Stewardship Blocks: Innovative Tool Brings Fire Plan Benefits into
Community
4. Youth Training Needed for Fire Plan to Benefit Local Workforce
5. Grants Get National Fire Plan Money into Communities
6. Collaborative Forest Restoration Program Creates New Solution to
Gridlock
7. Permits Regulate Prescribed Burning On Private Land
8. Accountability Remains a Key Issue for National Fire Plan
9. National Partnership Advances Landscape-Scale Forest Restoration
10. Poor Communities Most Threatened By Wildfire
11. A New Model To Fire-Proof Forest Homes
12. Consensus Over Fuel Reduction Treatment Dissolves
13. Wildland Urban Interface Definition Needed For Effective Policy
14. Funding Gaps Prevent Completion Of Hazardous Fuel Reduction
15. Agencies Propose to Streamline Environmental Review for Hazardous
Fuel Reduction Treatments
16. National Fire Plan Provides Economic Opportunity For Rural Residents
COMMUNITY STEWARDSHIP COMMUNICATOR is an electronic bulletin that
provides information about the national Community Stewardship
Collaborative’s effort to find solutions to issues related to
large-scale watershed projects on the national forests and the National
Fire Plan. The bulletin is prepared by the Pinchot Institute for
Conservation and is available by contacting nra-@pinchot.org
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