Influence of Fire Frequency on Carbon Consumption in Alaskan Black Spruce Forests

Elizabeth E Hoy, NASA GSFC / Global Science and Technology, Inc., elizabeth.hoy@nasa.gov (Presenter)
Tatiana Loboda, Univ. Maryland, loboda@umd.edu
Merritt R. Turetsky, University of Guelph, mrt@uoguelph.ca
Kirsten Barrett, University of Leicester, kb308@le.ac.uk
Eric S. Kasischke, NASA/University of Maryland, eric.s.kasischke@nasa.gov

Higher temperatures and drier conditions within the boreal forests of Alaska since 2000 have resulted in increases in burned area and fire frequency, which alter carbon storage and emissions. Analyses of satellite remote sensing data showed that >20% of the area impacted by fires in interior Alaska occurred in areas that had previously burned since 1950 (e.g., short to intermediate interval fires). Field studies showed that in immature black spruce forests ~ 35 to 55 years old organic layers experienced deep burning regardless of topographic position or seasonality of burning, factors that control depth of burning in mature black spruce forests. Here, refinements were made to a carbon consumption model to account for variations in fuel loads and fraction of carbon consumed associated with fire frequency based on quantifying burned area in recently burned sites using satellite imagery. An immature black spruce (Picea mariana) fuel type (including stands of ~0-50 years) was developed which contains new ground-layer carbon consumption values in order to more accurately account for differences between various age classes of black spruce forest. Both versions of the model were used to assess carbon consumption during 100 fire events (over 4.4 x 10^6 ha of burned area) from two recent ultra-large fire years (2004 and 2005). Using the improved model to better attribute fuel type and consumption resulted in higher ground-layer carbon consumption (4.9% in 2004 and 6.8% in 2005) than previously estimated. These adjustments in ground-layer burning resulted in total carbon consumption within 2004 and 2005 of 63.5 and 42.0 Tg of carbon, respectively. Results from this research are being incorporated into larger scale modeling efforts (see poster by T. Loboda et al. “The Alaska Forest Disturbance Carbon Tracking System”) to better assess changes in the climate-fire-vegetation dynamics in interior Alaskan boreal forests, and to understand the impacts of these changes on carbon consumption and emissions.

Presentation Type:  Poster

Session:  Theme 2: Landscapes to coasts: understanding Earth system connections   (Mon 1:30 PM)

Associated Project(s): 

• Hoy, Liz: Impacts of a changing fire frequency on soil carbon stocks in interior Alaskan boreal forests ...details
• Kasischke, Eric: Assessing the Impacts of Fire and Insect Disturbance on the Terrestrial Carbon Budgets of Forested Areas in Canada, Alaska, and the Western United States ...details
• Kasischke, Eric: The influence of fire-free interval on carbon cycling in the Alaskan boreal forest ...details
• McGuire, Dave: Assessing the Impacts of Fire and Insect Disturbance on the Terrestrial Carbon Budgets of Forested Areas in Canada, Alaska, and the Western United States ...details

Poster Location ID: 99