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Landscape Patterns of Vegetation Burning in Ecosystems of Interior Alaska Derived from Satellite Image Analysis and Field Measurements

Christopher Potter, NASA ARC, chris.potter@nasa.gov (Presenter)

In the summer of 2015, hundreds of forest fires burned across the state of Alaska. Several uncontrolled wildfires near the town of Tanana on the Yukon River were responsible for the largest portion of the area burned statewide. In July 2017, field measurements were carried out in both unburned and burned forested areas nearly adjacent to one-another to visually verify locations of different burn severity classes (low, moderate, or high) estimated in 2016 from MODIS and Landsat satellite images. Spatial analysis of landscape patterns of vegetation burning and severity classes were mapped in association with topography, pre-fire live biomass density, and land cover types. Results showed that the time-course of fire spread was repeated in several cycles, from relatively higher elevations (> 100 m), to lower elevations (< 30 m), and on slopes of greater than 10% to slopes lower than 5%. Burning cycles were also associated with higher-to-lower pre-fire NDVI burning and (pre-fire) land cover classes of predominantly forest and shrub cover at the beginning of a cycle, into herbaceous grasslands and river flats at the end of each cycle. Results from field measurements in unburned and nearby burned forest sites, all within 15 miles of the village of Tanana in 2017, were consistent with the hypothesis that the loss of surface organic layers in boreal ecosystem fires is a major factor determining post-fire soil temperature changes and the depth of thawing. Soil temperature profiles to 30 cm depth at burned forest sites increased by an average of 8o - 10o C compared to unburned forest sites.

Associated Project(s): 

Poster Location ID: 9

Session Assigned: Carbon Dynamics

 


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