Fine-scale Observations of Permafrost After Repeat Fires in Interior Alaska
Abstract
Permafrost in the boreal forest contains large amounts of carbon that is released as the permafrost thaws. Warming temperatures have led to both an increase in permafrost melt and an increase in the freq uency of wildfires , as shown in the recent 2019 fire season . Wildfires have been thought to a ccelerate permafrost melt , but t here has been little fine-scale research done on the relationship between frequency of forest fires and the specific resulting amount of permafrost thaw. Understanding this interaction is crucial to understanding both the role of the boreal forest in contributing to atmospheric carbon dioxide levels and how permafrost levels influence forest recovery post-fire. In order to understand this relationship at a fine scale, we investigated the effect of forest fires on permafrost thaw by comparing the depth of permafrost active layer at locations in boreal forest that remain unburned to locations that have burned one, two, or three times within the last 7 0 years. Specific depth to a ctive layer was evaluated at more than 30 sampling sites ranging in burn frequency using a soil probe at a minimum of 10 points in each plot. Our results provide us with a distribution map of permafrost patterns in burned areas, and a detailed inventory of the effects of postfire fine - scale (meter scale) ground cover heterogeneity on relative differences in active layer depth. Preliminary results indicate a strong relationship between multiple fires and amplification of permafrost thaw a s insulating layers of ground cover and tree canopy are reduced according to local variations in fire intensity. Furthermore, spatial heterogeneity in ground cover, woody debris, and standing dead influence the spatial distribution of depths within each burn frequency treatment. Results of this study indicate the importance of evaluating fine-scale variations in topography when examining postfire permafrost thaw in boreal Interior Alaska.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B13K2611O
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0793 Biogeochemistry;
- CRYOSPHERE;
- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY