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Climate Change and Wildfires








SEPTEMBER 24, 2007 

Mr. Chairman and Members of the Committee, thank you for the opportunity to provide this statement for the record on climate change and its impacts on wildfire activity in the United States.  My name is Thomas R. Armstrong, and I am the senior advisor for global change programs at the U.S. Geological Survey (USGS).  I also represent USGS and the Department of the Interior (DOI) as a member of the U.S. Climate Change Science Program (CCSP).

Climate change is perhaps the most complex and multi-faceted challenge facing public land managers.  Although climate change is a natural, continuous Earth process, changes to the Earth's climate are related to human activities as well.  Whether the causes are natural or from human influence, the USGS climate change focus is on understanding its impacts and the potential adaptive strategies for managing natural resources and ecosystems in the face of these changes. 

Climate change affects biota, water, ecosystems, cultures, and economies.  To effectively manage its public lands and trust resources, the DOI, working within the broader U.S. interagency climate change science framework, must advance the scientific understanding of climate change processes and impacts.  The USGS, a DOI bureau, has a long and distinguished history of conducting research, monitoring and modeling of climate change and its physical and biological impacts.  The USGS conducts scientific research to understand the likely consequences of climate change, especially by studying how climate has changed in the past and using the past to forecast responses to shifting climate conditions in the future; distinguishing between natural and human-influenced changes; and recognizing ecological and physical responses to changes in climate. For example, USGS scientists and colleagues have created sophisticated models that relate wildland fire patterns to decadal climatic variability (Swetnam and Tegancourt 1998). USGS researchers have also investigated plant, animal, soil, and water responses to fire through field-based empirical investigations for more than 40 years (Van Wagtendonk 1983, 1994; Keely 2004).  These capabilities and strengths allow the USGS to play a critical role in conducting climate change science across the Nation's terrestrial, freshwater, and coastal systems and in providing objective science to assist decision makers.

The DOI has taken bold steps to coordinate and focus its efforts in climate change.  Secretary Kempthorne has convened a Climate Change Task Force to address the land management and stewardship challenges presented by a changing climate.  The task force includes three subcommittees – one on legal and policy issues; a second on land and water management issues; and a third, which I chair, dealing with climate change scientific issues specifically related to the DOI's responsibilities.  This latter subcommittee is exploring development of regional scale models to better forecast location-specific changes to the landscapes we manage.  In addition, it is evaluating information needs to determine whether more extensive and integrated monitoring might strengthen the understanding of on-the-ground trends in the forces of climate and how they influence water availability, vegetative patterns (including proliferation of invasive species and the health and integrity of native plant communities), wildlife habitat, the future viability of threatened and endangered species, and wildfires.

A changing climate may profoundly shape future impacts of wildfires throughout the United States, North America, and the rest of the planet (Westerling et al. 2006).  A changing climate is expected to produce major shifts in the timing and magnitude of local to regional precipitation patterns, the types and distribution of vegetation, including invasive species, and the types and volumes of fire fuel loads- and thus fire frequency, severity, and intensity.  For example, as precipitation patterns in desert ecosystems change, opportunistic species such as red brome and cheatgrass invade. USGS research shows that these invasive species alter the natural ecosystems and fire regimes, leading to hotter burning fires that further alter soils and ecosystems (Whisenant 1990; Knapp 1996; Young and Evans 1978; Brooks and Pyke 2001; Suring et al. 2005; Miller and Tausch 2001).

While DOI bureaus have management responsibility for both forest and rangeland habitat, a large portion of that habitat is in rangeland.  Natural and human-caused disturbances have interacted over the past several decades to change rangelands and pinyon-juniper ecosystems across as much as one half of the Great Basin's one hundred million acres (McIver et al. 2004).  Protracted drought coupled with invasive species, altered fire regimes, grazing, human settlement and recreation, and energy exploration and development have yielded suites of vegetation that often cannot support wildlife species.  Increasing annual temperature and decreasing precipitation regimes have exacerbated these ecological changes, and climate change will continue to interact with plant and animal dynamics on dry lands.  As a result of these rapid and widespread changes, the sagebrush biome is becoming widely recognized as among North America's most "at-risk ecosystems" (Noss 1995).

Encroachment of native conifers such as juniper on the more mesic or moisture-balanced lands of the sage biome has shifted fire regimes from frequent, low- and mixed-severity fires to infrequent, high-severity fires.  Fuel loads have increased as much as six-fold (McIver et al. 2004).  Changes in the size and severity of wildfires and in the type and patterns of precipitation, whether snow or rain, falling on burned areas may have significant effects on the biological and hydrological response of large areas of the landscape (Omi 2005).  One unknown is the impact of climate change on the distribution of State or federal listed noxious weed species.

Expansion of some invasive species, particularly cheatgrass and red brome which can serve as highly flammable fuels, have changed fire return intervals on the more xeric or dry interior rangelands from more than 50 years to less than 10 years (Miller and Tausch 2001).  Another recent study found that cheatgrass biomass increases are stimulated by increasing carbon dioxide levels (Ziska et al. 2005).  This study also found that cheatgrass will become more coarse (e.g., lignin content will increase) in the future, reducing the time that it is palatable to livestock and wildlife and causing fuel loads to accumulate due to reduced decomposition rates. 

USGS research supports land-management agencies by working to discover the site-specific conditions where management actions, such as fire suppression and mechanical treatments, can restore rangeland vegetation to habitat suitable for critical wildlife species such as the sage grouse.  Better decision making tools mean better management of land resources, and they provide the support necessary to manage wildland fuels and wildfires through more cost-effective means.

The USGS, in some cases in collaboration with universities or management agencies and with the support of the Joint Fire Science Program, conducts fire-related research to meet the varied needs of resource managers and to understand the role of fire on the landscape. This research includes fire management support, studies of post-fire effects and habitat restoration, and a wide range of studies on fire history and ecology.  The ongoing mountain pine beetle epidemic, a consequence of long-term drought, perhaps related to climate change, has devastated forests throughout the West, thus creating a potential for catastrophic wildfires that may affect the natural ecosystems, homes and communities, including municipal water supplies, and local economies.  The USGS is involved in multi-agency efforts to identify the bark beetle spread, tree mortality, and the potential for post-fire debris flows and water-quality effects.  These efforts include the Colorado Front Range Fuels Treatment Partnership and the Northern Colorado Bark Beetle Cooperative, partnerships that include not only USGS but also the U.S. Forest Service, the National Park Service, the Bureau of Land Management, the U.S. Fish and Wildlife Service, and other State and local agencies.

To better understand the interaction between climate change and fire, and provide the science needed by resource managers and decision makers, the USGS is working to develop:

·         A better understanding of fire's ecological role over the full range of biophysical settings and ecosystems. Basic fire ecology identifies biological sensitivities and dependencies, guiding management in prediction of post-fire consequences and in engineering the proper application of fire for long-term management. This understanding extends to physical processes within burned watersheds that affect restoration, runoff, erosion, sedimentation, debris-flow generation and water-quality issues. Recent USGS research efforts include collection and analysis of samples from the June 2007 Angora Fire on the shores of Lake Tahoe to determine potential water-quality and health effects of ash.  Additionally, models developed by USGS scientists can be used to predict the probability and quantity of debris flows after wildfire.

·         Means for securing better and more timely empirical data on fire effects and responses. This includes the development of new methodologies, technologies such as remote sensing, or approaches for quantifying and mapping active fires and post-fire effects, as well as standardizing field sampling.

·         A better scientific understanding of the factors that influence fire regimes and post-fire effects, such as climate, precipitation, change in vegetation type and pattern, fuel, and insect and pathogen invasions.

·         Methods to integrate the preceding topics to address emergency response, treatments and prescriptions, priority setting, fuel reduction, risk assessment, safety, public information, and cost effectiveness.

Also, in partnership with the USDA Forest Service and the Nature Conservancy, USGS continues to provide a pivotal role in developing the LANDFIRE project – mapping and modeling of vegetation, fuel conditions, and a suite of other data. These products benefit landowners and land managers throughout the country.

In summary, wildfires are a serious and growing hazard over much of the United States. They threaten life and property, particularly when they move from forest or rangeland into developed areas. This situation may be exacerbated by a changing climate.  USGS fire-related research that includes fire management support, studies of post-fire effects, and studies of fire history and ecology are essential to understanding and forecasting the impacts of climate change on forest and rangeland ecosystems.  An improved understanding and the ability to forecast future impacts can serve as the scientific foundation upon which fire management and land management decisions can be based.

Mr. Chairman, we appreciate your continued interest in this challenging land management issue, and we thank you for the opportunity to present this statement.

References cited

Brooks, M. L., and D. A. Pyke. 2001. Invasive plants and fire in the deserts of North America. Pages 1–14 in K. E. M. Galley and T. P. Wilson, editors. Proceedings of the invasive species workshop: the role of fire in the control and spread of invasive species. Fire conference 2000: the First National Congress on Fire Ecology, Prevention, and Management. Miscellaneous Publication No. 11, Tall Timbers Research Station, Tallahassee, Florida, USA.

Keeley, J.E. 2004. Impact of antecedent climate on fire regimes in coastal California? International J. of Wildland Fire. 13:173-182.

Knapp, P. A. 1996. Cheatgrass (Bromus tectorum) dominance in the Great Basin Desert. Global Environmental Change 6:37–52.

McIver, J., Barrett, H., Brunson, M., Bunting, S., Chambers, J., D'Antonio, C., Doescher, P., Karl, S., Knick S., Miller, R., Pellant, M.,  Pierson, F., Pyke, D.,  Rollins, K., Roundy, B., Schupp, G., Tausch, R., Turner, D., Wisdom, M. 2004. A Regional Experiment to Evaluate Effects of Fire and Fire Surrogate Treatments in the Sagebrush Biome. Final revised deliverable of the 2003 JFSP grant entitled, "Designing an experiment to evaluate effects of fire and fire surrogate treatments in the sagebrush biome". USDA Forest Service Pacific Northwest Research Station.

Miller, R.F., and Tausch, R.J. 2001. The role of fire in pinyon and juniper woodlands. Pp 375-384 in S.B. Monsen and R. Stevens, compilers. Proceedings: ecology and management of pinyon-juniper communities within the interior west.  USDA Forest Service Rocky Mountain Research Station Proceedings RMRS-P-9.

Miller, R., R. Tausch, and W. Waichler. 1999. Old-growth juniper and pinyon woodlands. Pages 375-384 in S. B. Monsen and R. Stevens, compilers. Proceedings: ecology and management of pinyon-juniper communities within the interior west. USDA Forest Service Rocky Mountain Research Station Proceedings RMRS-P-9.

Noss, R.F., LaRoe, E.T., and Scott, J.M. 1995. Endangered ecosystems of the United States: a preliminary assessment of loss and degradation.  National Biological Service Biological Report 28. National Biological Service.  Washington D.C.

Omi, P.N. 2005. Forest Fires: A Reference Handbook. Pp. 174-175. ABC-CLIO. Santa Barbara, CA.

Suring, L. H., M. J. Wisdom, R. J. Tausch, R. F. Miller, M. M. Rowland, L. Schueck, and C. W. Meinke. 2005. Modeling threats to sagebrush and other shrubland communities. Pages 114–149 in M. J. Wisdom, M. M. Rowland, and L. H. Suring, editors. Habitat threats in the sagebrush ecosystems: methods of regional assessment and applications in the Great Basin. Alliance Communications Group, Lawrence, Kansas, USA.

Swetnam, T. W, and J. L. Betancourt, 1998: Mesoscale disturbance and ecological response to decadal climatic variability in the American southwest. J. Climate, 11, 3128–3147.

Swetnam, T. W., and J. L. Betancourt, 1990: Fire–Southern Oscillation relations in the southwestern United States. Science 249:1017-1020.  

Van Wagtendonk, J.W., 1983. Prescribed fire effects on forest understory mortality. Proc. 7th Conf. Fire and Forest Meteorology. 7:136-138.

Van Wagtendonk, J.W., 1994. Spatial patterns of lightning strikes and fires inYosemite National Park. Proc. 12th Conf. Fire and Forest Meteorology. 12:223-231

Westerling. A.L., H. G. Hidalgo, D. R. Cayan,  T. W. Swetnam. 2006.  Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity. Science. 313(5789): 940 – 943.

Whisenant, S. G. 1990. Changing fire frequencies on Idaho's Snake River Plains: ecological and management implications. Pages 4–10 in E. D. McArthur, E. M. Romney, S. D. Smith, and P. T. Tueller, compilers. Proceedings: symposium on cheatgrass invasion, shrub die-off and other aspects of shrub biology and management. USDA General  Technical Report INT-276, Ogden, Utah, USA.

Young, J. A., and R. A. Evans. 1978. Population dynamics after wildfires in sagebrush grasslands. Journal of Range Management 31:283–289.

Ziska, L.H., Reeves III, J.B., and Blank, B. 2005. The impact of recent increases in atmospheric CO2 on biomass production and vegetative retention of Cheatgrass (Bromus tectorum): implications for fire disturbance. Global Change Biology 11 (8), 1325–1332.