Tundra fire driven surface subsidence increases spectral diversity on the Yukon-Kuskokwim Delta, Alaska

Anderson, Duncan

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https://hdl.handle.net/2142/122065 Copy

Description

Title

Tundra fire driven surface subsidence increases spectral diversity on the Yukon-Kuskokwim Delta, Alaska

Author(s)

Anderson, Duncan

Issue Date

2023-12-06

Director of Research (if dissertation) or Advisor (if thesis)

• Lara, Mark J
• Cienciala, Piotr

Department of Study

Geography & GIS

Discipline

Geography

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

Spectral Diversity, Alaska, Tundra, Wildfire, Subsidence, Permafrost, Degradation, Vegetation Dynamics

Abstract

Tundra fires can dramatically influence plant species cover and abundance, organic layer depth, and the magnitude of seasonal permafrost thaw. However, the potential impact of wildfire on short and long-term interactions between vegetation and permafrost thaw remains poorly understood. We evaluated the spatial and temporal interactions between wildfire and surface subsidence on a remotely derived proxy for species diversity (i.e., spectral diversity). Spectral diversity and rates of surface subsistence were calculated using airborne hyperspectral AVIRIS-NG imagery and spaceborne interferometric synthetic aperture radar (InSAR) data from Sentinel-1. Spectral diversity was measured as the spectral variance within a plant community (alpha-diversity), between plant communities (beta-diversity), and across terrain composed of a mosaic of communities (gamma-diversity). The Yukon-Kuskokwim Delta in southwestern Alaska is one of the warmest and most productive tundra regions, with a documented history of upland fires, 16 of which were examined within the Izaviknek and Kingaglia uplands which occurred between 1971 and 2015. Results indicate the burn scars had consistently lower total gamma diversity and higher rates of subsidence than paired unburned reference areas, where both gamma diversity (R2 = 0.74, p < 0.001) and subsidence (R2 = 0.75, p < 0.001) decreased with the time since burn. Where, younger burn scars had both a higher gamma diversity (0.013) and subsidence rates (-0.097 cm day-1) than old scars with 0.005 and -0.053 cm day-1, respectively. Gamma diversity was also found to have a negative relationship with subsidence rates (R2 = 0.63, p < 0.001) where communities subsiding at a higher rate were more diverse. This study suggests that the patterns of plant species diversity and succession following wildfires are amplified by the thickening of active layers and surface subsidence that results in increased spectral diversity over 15 years following fire. These findings highlight the short and long-term ecological interactions that impact post-fire spectral-species succession that influence tundra ecosystem structure and function.

Graduation Semester

2023-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Duncan Anderson

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