COS 63-7 - Comparing pre-European and contemporary carbon emissions from wildfire in the montane forest of the Colorado Front Range, USA

Wednesday, August 10, 2011: 10:10 AM
13, Austin Convention Center
Sara Brown, Botany, University of Wyoming, Laramie, WY, Ingrid C. Burke, Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY, Peter M. Brown, Rocky Mountain Tree-ring Research, Inc., Fort Collins, CO, William K. Lauenroth, Department of Botany, University of Wyoming, Laramie, WY and Daniel R. Schlaepfer, Section of Conservation Biology, University of Basel, Basel, Switzerland

Wildfires in the Colorado montane forest burned with no anthropogenic suppression for millennia leading up to European settlement beginning in the late 19th century. In this study I examine the period between 1700-1900 (“pre-European”). Fires have been successfully suppressed during recent decades (~1950-2010) in this region, likely reducing the spatial extent of these fires. The spatial extent of wildfire is a major control over C emissions to the atmosphere during combustion. The objective of my study was to determine how C emissions from fires differ between contemporary and pre-European periods in the Colorado Front Range montane forest. I used LANDFIRE national data sets to determine vegetation-type changes across the time periods. Tree-ring data from 84 sites across the study area provided fire frequency and spatial extent estimates of fires during my pre-European time period. Recent fire records from national, private and state lands provide frequency and spatial extent data for the contemporary time period. I developed C emission estimates for both pre-European and contemporary data sets at the vegetation-type level using estimates I derived from previous work completed in the study area.


I found that wildfires were more spatially extensive during the pre-European period (an average of ~330 km2 yr¬-1 burned) as compared to the contemporary period (an average of ~22 km2 yr¬-1 burned). Average yearly C loss estimates from the pre-European period were considerably larger (2.5 ± 1.3 Tg yr¬-1) compared to the contemporary estimate (0.012 ± 0.006 Tg yr¬-1). Fire suppression and other contemporary forest management techniques have impacted the spatial extent of fire in the Colorado montane forest, and thus have impacted the magnitude of pyrogenic carbon emissions. With expected increases in the spatial extent of fires in the future, these results suggest that pyrogenic emissions from these forests could greatly affect the atmospheric pool.

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