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. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 14 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Electrical resistivity tomography (ERT) data collected along the 14 transect were used to map the spatial distribution of permafrost across burned-unburned boundaries.

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. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 14 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Downhole nuclear magnetic resonance (NMR) data are used to quantify in situ unfrozen water content in shallow auger holes.

Geophysical measurements were collected by the U.S. Geological Survey (USGS) at five sites in Interior Alaska in September 2021 for the purposes of imaging permafrost structure and quantifying variations in subsurface moisture content in relation to thaw features. Electrical resistivity tomography (ERT) measurements were made along transects 110 - 222 m in length to quantify subsurface permafrost characteristics. ERT transects were collected across a fireline boundary within the Bonanza Creek Long Term Ecological Research (LTER) site where repeat measurements have been made since 2014; across and adjacent to two thermokarst lakes, Vault Lake and Goldstream Lake; and along two profiles at the North Star golf course in Fairbanks, Alaska. Models of electrical resistivity produced from these data revealed the distribution of frozen and thawed soil to depths of 10-40 m below the surface. Manual permafrost-probe measurements of thaw depths were collected at set intervals along each ERT transect used for comparison to the geophysical measurements, except at the North Star golf course where shallow permafrost was absent.

This release contains Active Layer Thickness (ALT) and Organic Layer Thickness (OLT) measurements measured along transects in Alaska, 2015. Site condition information in terms of wildfire burns is also included.

Geophysical measurements and related field data were collected by the U.S. Geological Survey (USGS) at the Alaska Peatland Experiment (APEX) site in Interior Alaska from 2018 to 2020 to characterize subsurface thermal and hydrologic conditions along a permafrost thaw gradient. The APEX site is managed by the Bonanza Creek LTER (Long Term Ecological Research). Nine instrument monitoring sites (APEX1-APEX9) were established in April 2018. To quantify permafrost and thaw zone characteristics along the instrumented gradient, electrical resistivity tomography (ERT) data were collected in August 2018 along four 82 meter (m)-long transects between select sites: APEX1-3, APEX5-3, APEX5-7, and APEX6-8. Data were collected for both dipole-dipole (DD) and inverse Schlumberger (IS) survey geometries. Inverted models of electrical resistivity were produced from the separate DD and IS datasets, as well as the combination of both datasets inverted jointly (labeled DDIS). The resulting models of electrical resistivity revealed the spatial variability in soil lithology and thermal state (frozen vs. thawed) to depths up to 10-15 m below the surface. Manual permafrost-probe measurements of thaw depths were collected at set intervals along each ERT transect and used for comparison to the resistivity models.

Electrical resistivity tomography (ERT) measurements were collected by the U.S. Geological Survey (USGS) at two sites in Interior Alaska in September 2019 for the purposes of imaging permafrost structure and quantifying variations in subsurface moisture content in relation to thaw features. First, ERT data were collected at Big Trail Lake, a thermokarst lake outside of Fairbanks, Alaska, to quantify permafrost characteristics beneath the lake and across its shorelines. Three 222 m ERT survey lines were collected perpendicular to the North, East, and South shorelines, and two 110 m lines were collected parallel to the southeast and northeast shorelines. Models of electrical resistivity produced from these data revealed the distribution of frozen and thawed soil to depths of 10-40 m below the surface. Second, an ERT survey was conducted at Bonanza Creek LTER (Long Term Ecological Research), approximately 30 km southwest of Fairbanks, Alaska. This survey was a repeat of a previous ERT survey done in the same exact location in late August 2016, those data and models can be found here. The new survey line was 125 m in length and spanned the transition between burned and unburned forest. Models of electrical resistivity for this site imaged the structure of frozen and thawed soils to depths of 10-15 m. At both sites, manual permafrost-probe measurements of thaw depths were collected at set intervals along each ERT transect and used for comparison to the resistivity models.

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. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 14 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Downhole nuclear magnetic resonance (NMR) data are used to quantify in situ unfrozen water content in shallow auger holes.

This release contains plant species cover measured along transects in Alaska, 2015. Site condition information in terms of wildfire burns is also included.

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. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected along the 11 transect locations include: electrical resistivity tomography (ERT), downhole nuclear magnetic resonance (NMR), active layer thickness (ALT), organic layer thickness (OLT), and plant species cover. These geospatial datasets are the foundation for the journal article: Minsley, B. J., N. J. Pastick, B. K. Wylie, D. R. N. Brown, and M. Andy Kass (2016), Evidence for nonuniform permafrost degradation after fire in boreal landscapes, J. Geophys. Res. Earth Surf., 121, 320–335, doi:10.1002/2015JF003781.

Electrical resistivity tomography (ERT), downhole nuclear magnetic resonance (NMR), and manual permafrost-probe measurements were used to quantify permafrost characteristics along transects within several catchments in interior Alaska in late summer 2016 and 2017. Geophysical sites were chosen to coincide with additional soil, hydrologic, and geochemical measurements adjacent to various low-order streams and tributaries in a mix of burned and unburned watersheds in both silty and rocky environments. Data were collected in support of the Striegl-01 NASA ABoVE project, "Vulnerability of inland waters and the aquatic carbon cycle to changing permafrost and climate across boreal northwestern North America." Additional geophysical measurements were conducted at the Bonanza Creek LTER and at a thermokarst bog site. ERT transects were 100 - 200 m in length, and produce models of electrical resistivity structure to depths of 10 - 15 m that indicate the distribution of frozen ground with high spatial resolution. Manual permafrost-probe measurements were made periodically along ERT transects to validate the depth to the top of permafrost. Downhole NMR measurements were made at select locations near the ERT transects to quantify in situ unfrozen water content and to help constrain interpretations of electrical resistivity models.