Carbon stocks of trees killed by bark beetles and wildfire in the western United States

Forests are major components of the carbon cycle, and disturbances are important influences of forest carbon. Our objective was to contribute to the understanding of forest carbon cycling by quantifying the amount of carbon in trees killed by two disturbance types, fires and bark beetles, in the western United States in recent decades. We combined existing spatial data sets of forest biomass, burn severity, and beetle-caused tree mortality to estimate the amount of aboveground and belowground carbon in killed trees across the region. We found that during 1984‐2010, fires killed trees that contained 5‐11 Tg C year 1 and during 1997‐2010, beetles killed trees that contained 2‐24 Tg C year 1 , with more trees killed since 2000 than in earlier periods. Over their periods of record, amounts of carbon in trees killed by fires and by beetle outbreaks were similar, and together these disturbances killed trees representing 9% of the total tree carbon in western forests, a similar amount to harvesting. Fires killed more trees in lower-elevation forest types such as Douglas-fir than higher-elevation forest types, whereas bark beetle outbreaks also killed trees in higher-elevation forest types such as lodgepole pine and Engelmann spruce. Over 15% of the carbon in lodgepole pine and spruce/fir forest types was in trees killed by beetle outbreaks; other forest types had 5‐10% of the carbon in killed trees. Our results document the importance of these natural disturbances in the carbon budget of the western United States.

[1]  H. L. Miller,et al.  Climate Change 2007: The Physical Science Basis , 2007 .

[2]  G. P. Zimmerman,et al.  The first state of the carbon cycle report (SOCCR): The North American carbon budget and implications for the global carbon cycle. , 2007 .

[3]  Daniel M. Kashian,et al.  Effects of biotic disturbances on forest carbon cycling in the United States and Canada , 2012 .

[4]  G. Powell,et al.  Terrestrial Ecoregions of the World: A New Map of Life on Earth , 2001 .

[5]  Yonghe Wang,et al.  Canada’s Forest Biomass Resources: Deriving Estimates from Canada’s Forest Inventory , 1997 .

[6]  J. Régnière,et al.  Climate Change and Bark Beetles of the Western United States and Canada: Direct and Indirect Effects , 2010 .

[7]  C. Wiedinmyer,et al.  Estimates of CO2 from fires in the United States: implications for carbon management , 2007, Carbon balance and management.

[8]  R. Peet,et al.  Gradient analysis of latitudinal variation in southern Rocky Mountain forests , 1991 .

[9]  R Daubenmire,et al.  Vegetation: identification of typal communities. , 1966, Science.

[10]  J. Randerson,et al.  Model comparisons for estimating carbon emissions from North American wildland fire , 2011 .

[11]  W. Schlesinger.  Biogeochemistry: An Analysis of Global Change , 1991 .

[12]  G. Zúñiga,et al.  Areography of the genus Dendroctonus (Coleoptera: Curculionidae: Scolytinae) in Mexico , 2004 .

[13]  M. D. Nelson,et al.  Mapping U.S. forest biomass using nationwide forest inventory data and moderate resolution information , 2008 .

[14]  G. James Collatz,et al.  Fire‐induced carbon emissions and regrowth uptake in western U.S. forests: Documenting variation across forest types, fire severity, and climate regions , 2012 .

[15]  M. G. Ryan,et al.  Postfire changes in forest carbon storage over a 300‐year chronosequence of Pinus contorta‐dominated forests , 2013 .

[16]  Corinne Le Quéré,et al.  Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks , 2007, Proceedings of the National Academy of Sciences.

[17]  J. Hicke,et al.  Cross-scale Drivers of Natural Disturbances Prone to Anthropogenic Amplification: The Dynamics of Bark Beetle Eruptions , 2008 .

[18]  Christopher B. Field,et al.  Postfire response of North American boreal forest net primary productivity analyzed with satellite observations , 2003 .

[19]  Steven D. Chandler.  Radioactive waste policy and legislation: 50 years on from the 1960 Act , 2011, Journal of radiological protection : official journal of the Society for Radiological Protection.

[20]  J. W. Wagtendonk,et al.  Mapped versus actual burned area within wildfire perimeters: Characterizing the unburned , 2012 .

[21]  Kenneth L. Clark,et al.  Ecosystem carbon dioxide fluxes after disturbance in forests of North America , 2010 .

[22]  D. Peterson,et al.  Climate and wildfire area burned in western U.S. ecoprovinces, 1916-2003. , 2009, Ecological applications : a publication of the Ecological Society of America.

[23]  C. Perry,et al.  Forest Resources of the United States, 2007 , 2009 .

[24]  W. Kurz,et al.  Mountain pine beetle and forest carbon feedback to climate change , 2008, Nature.

[25]  Eileen H. Helmer,et al.  Root biomass allocation in the world's upland forests , 1997, Oecologia.

[26]  M. G. Ryan,et al.  Carbon Storage on Landscapes with Stand-replacing Fires , 2006 .

[27]  D. Lawrence,et al.  Simulating coupled carbon and nitrogen dynamics following mountain pine beetle outbreaks in the western United States , 2011 .

[28]  Guido Grosse,et al.  Impacts of disturbance on the terrestrial carbon budget of North America , 2013 .

[29]  R. Vargas,et al.  Heterotrophic respiration in disturbed forests: A review with examples from North America , 2011 .

[30]  D. Riaño,et al.  Quantifying burned area for North American forests: Implications for direct reduction of carbon stocks , 2011 .

[31]  E. Odum.  The strategy of ecosystem development. , 1969, Science.

[32]  Kenneth L. Denman Canada.  Couplings between changes in the climate system and biogeochemistry , 2008 .

[33]  B. Quayle,et al.  A Project for Monitoring Trends in Burn Severity , 2007 .

[34]  A. Ditta.  How helpful is nanotechnology in agriculture? , 2012 .

[35]  R. B. Jackson,et al.  A Large and Persistent Carbon Sink in the World’s Forests , 2011, Science.

[36]  J. Hicke,et al.  Spatiotemporal patterns of observed bark beetle-caused tree mortality in British Columbia and the western United States. , 2012, Ecological applications : a publication of the Ecological Society of America.

[37]  Christopher B. Field,et al.  FOREST CARBON SINKS IN THE NORTHERN HEMISPHERE , 2002 .

[38]  J. Randerson,et al.  Global fire emissions and the contribution of deforestation, savanna, forest, agricultural, and peat fires (1997-2009) , 2010 .

[39]  M. D. Nelson,et al.  Conterminous U.S. and Alaska Forest Type Mapping Using Forest Inventory and Analysis Data , 2008 .