Conterminous U.S. Forest Disturbance Dynamics Evaluated from Landsat Time Series Stacks
Nancy
E.
Thomas, Department of Geography, University of Maryland, nthomas1@umd.edu
(Presenting)
Samuel
N.
Goward, Department of Geography, University of Maryland, sgoward@umd.edu
Robert
Kennedy, Oregon State University, robert.kennedy@oregonstate.edu
Jeffrey
G.
Masek, NASA Goddard Space Flight Center, jeffrey.g.masek@nasa.gov
Warren
B.
Cohen, USDA Forest Service, warren.cohen@oregonstate.edu
Gretchen
G.
Moisen, USDA Forest Service Rocky Mountain Research Station, gmoisen@fs.fed.us
Chengquan
Huang, Department of Geography, University of Maryland, cqhuang@umd.edu
Karen
Schleeweis, Department of Geography, University of Maryland, ska1@umd.edu
Current substantial North America carbon emissions are partially offset by carbon uptake in growing forests. However, the magnitude and sustainability of forest carbon sequestration is highly uncertain. The underlying forest dynamics—including extent, rate, and magnitude of change events such as fire, harvest, insect damage, and disease—are not currently well understood. Without improved understanding of these forest dynamics, prediction of the future role of North American forests and woodlands in carbon sequestration will be nearly impossible.
Within the North American Forest Dynamics (NAFD) project, a core project of the North American Carbon Program (NACP), we are evaluating forest disturbance and regrowth patterns by combining U.S. Forest Service Forest Inventory and Analysis (FIA) field measurements with biennial Landsat observations. Phase I of the NAFD study examined U.S. national forest dynamics and disturbance history from Landsat time series stacks (LTSS) for 23 sample locations over the time period 1984-2005. Sample sites were selected to support derivation of unbiased national estimates of disturbance rates. Phase I results show a mean disturbance rate of 2.09 M ha/yr in the east and 0.75 M ha/yr in the western forests for this time period. These estimates suggest that eastern forests are replaced every 78 years, with western forest replacement occurring every 122 years. These results are somewhat lower than previous estimates from forest inventory data. Our results also show significant inter-annual variation in disturbance rates which are driven by regional and localized events. We see a large increase in disturbance rates for western forests from 1999-2002, with the greatest increase related to locations in the Interior West. Eastern forests show higher rates from 1997 to 2000 and lower disturbance rates in the early 1990’s and 2000s, with southern forests variations dominating the eastern variability. This poster presents the national estimate results and addresses the implications of highly variable regional and temporal disturbance patterns for nation-wide carbon monitoring.
Presentation Type: Poster
Poster Session: Carbon Cycle Science
NASA TE Funded Awards Represented:
Goward, Samuel
Role of North America Forest Disturbance and Regrowth In NACP: Integrated Analyzes Of Landsat and U.S. Forest Service FIA Data - Phase 2