The impact of fire disturbance on carbon and energy exchange in the Alaskan boreal region: A geospatial data analysis.

摘要

The goal of research was to measure and evaluate the impact of fire on land surface albedo and carbon exchange in the boreal region of Alaska by employing remote sensing and geospatial methods. Two research studies explore the landscape-scale impacts of fire on land cover and energy balance and broad-scale impact on carbon exchange. Summertime land surface albedo change from fire disturbance in an Alaska black spruce dominated landscape was studied using Landsat image data. Albedo is key in determining surface net radiation and can be dramatically changed by fire. Fire-induced albedo change was found to be spatially and temporally variable based on pre-burn vegetation, canopy density, burn severity, and site age. In typical fire-affected sites in Alaska—sites of medium density black spruce and moderate burn severity—no significant change in albedo was found within the first year. At all sites albedo increased after several years of vegetation growth. Estimated long-term changes are substantial enough to directly impact net radiation. In a second study, carbon (C) released from fire in the Alaskan boreal region was estimated using geospatial data sets and a Geographic Information System (GIS)-based model. An estimated 4.5 TgC is released annually. In a high fire year, C released during fire was found to be substantial when compared with NEP, but annually variable. Geospatial analysis techniques allow for more accurate, spatially defined data, providing for local variation in model inputs, resulting in more accurate regional C release estimates. Multi-scale analyses of land cover change using geospatial data and remote sensing methods reveal important impacts of fire disturbance on carbon and energy exchange which can be used with terrestrial ecosystem models for a broad understanding of fire's impact.