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Patterns of Canopy and Surface Layer Consumption in a Boreal Forest Fire from Repeat Airborne LidarFire in the boreal region is the dominant agent of forest disturbance with direct impacts on ecosystem structure, carbon cycling, and global climate. Global and biome-scale impacts are mediated by burn severity, measured as loss of forest canopy and consumption of the soil organic layer. To date, knowledge of the spatial variability in burn severity has been limited by sparse field sampling and moderate resolution satellite data. Here, we used pre- and post-fire airborne lidar data to directly estimate changes in canopy vertical structure and surface elevation for a 2005 boreal forest fire on Alaskas Kenai Peninsula. We found that both canopy and surface losses were strongly linked to pre-fire species composition and exhibited important fine-scale spatial variability at sub-30m resolution. The fractional reduction in canopy volume ranged from 0.61 in lowland black spruce stands to 0.27 in mixed white spruce and broad leaf forest. Residual structure largely reflects standing dead trees, highlighting the influence of pre-fire forest structure on delayed carbon losses from above ground biomass, post-fire albedo, and variability in understory light environments. Median loss of surface elevation was highest in lowland black spruce stands (0.18 m) but much lower in mixed stands (0.02 m), consistent with differences in pre-fire organic layer accumulation. Spatially continuous depth-of-burn estimates from repeat lidar measurements provide novel information to constrain carbon emissions from the surface organic layer and may inform related research on post-fire successional trajectories. Spectral measures of burn severity from Landsat were correlated with canopy (r = 0.76) and surface (r = -0.71) removal in black spruce stands but captured less of the spatial variability in fire effects for mixed stands (canopy r = 0.56, surface r = -0.26), underscoring the difficulty in capturing fire effects in heterogeneous boreal forest landscapes using proxy measures of burn severity from Landsat.
Document ID
20170008031
Document Type
Reprint (Version printed in journal)
Authors
Alonzo, Michael
(American Univ. Washington, DC, United States)
Morton, Douglas C.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Cook, Bruce D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Andersen, Hans-Erik
(Forest Service Seattle, WA, United States)
Babcock, Chad
(Washington Univ. Seattle, WA, United States)
Pattison, Robert
(Forest Service Anchorage, AK, United States)
Date Acquired
August 30, 2017
Publication Date
May 26, 2017
Publication Information
Publication: Enviromental Research Letters
Volume: 12
Issue: 6
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN45849
Distribution Limits
Public
Copyright
Other
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