Geological Society of America

T310 Hydrogeological and Geomorphological Responses to El Niño, Extreme Weather Events, and Landscape Disturbances

Wednesday, 28 September 2016
1:30 PM - 5:30 PM
Mile High Ballroom 3B

GEOPHYSICAL EVIDENCE FOR NON-UNIFORM PERMAFROST DEGRADATION AFTER FIRE ACROSS BOREAL LANDSCAPES

Paper number: T310-11
Program: Technical Sessions
Time: 4:00 PM – 4:20 PM

Authors

Burke Minsley Presenting Author
U.S. Geological Survey, Denver, CO
Neal J. Pastick
Stinger Ghaffarian Technologies, Inc., Sioux Falls, SD
Neal J. Pastick
University of Minnesota, St. Paul, MN
B.K. Wylie
USGS Center for Earth Resources and Observation Science, Sioux Falls, SD
Dana R.N. Brown
University of Alaska Fairbanks, Fairbanks, AK
M. Andy Kass
US Geological Survey, Denver, CO

Abstract

Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. We present a combination of multi-scale remote sensing, geophysical, and field observations that reveal details of both near-surface (<1 m) and deeper impacts of fire on permafrost. Along 23 transects that span burned-unburned boundaries in different landscape settings within interior Alaska, subsurface imaging indicates locations where permafrost appears to be resilient to disturbance from fire, areas where warm permafrost conditions exist that may be most vulnerable to future change, and also where permafrost has thawed. High-resolution geophysical data corroborate remote sensing interpretations of near-surface permafrost, and also add new high-fidelity details of spatial heterogeneity that extend from the shallow subsurface to depths of about 10 m. Data collected along each transect include observations of active layer thickness (ALT), organic layer thickness (OLT), plant species cover, electrical resistivity tomography (ERT), and downhole Nuclear Magnetic Resonance (NMR) measurements. Results show that post-fire impacts on permafrost can be variable, and depend on multiple factors such as fire severity, soil texture, and soil moisture.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-283447

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