Characterizing Alaskan wildfire regimes through remotely sensed data: Assessments of large area pattern and trend

Wildfires are an integral disturbance component of dynamic ecological communities, but for humans to thrive in wildfire-prone regions, they must mitigate wildfire risks to human infrastructure and ecosystem services. Boreal forest and tundra ecotypes have co-evolved with wildfire disturbances, but the nature of fire effects on the landscape boreal regions is poorly understood due to sparse human settlement. The most extensive work thus far covers Alaska, where five decades of research have focused primarily on localized wildfire as a catalyst for succession in the boreal forest. This dissertation explores wildfire regimes at a regional scale in the Alaskan interior through remotely sensed data. It uses an exploratory approach to identify spatial patterns and temporal trends in remotely-sensed wildfire activity, determines the relative influence of climate and vegetation on those trends, and describes the importance of understanding these trends to increase the accuracy of global emissions models.;The first paper examines novel approaches for representing ground-observed one-year post-wildfire impacts in concurrently-acquired remotely sensed data from two sensors. High correlation ranges between spectral indices and wildfire consumption of above-ground vegetation were found, and several bi-temporal indices were significantly correlated to ground observations of fire effects.;The second paper examines three assumptions held about wildfire regimes in the Alaskan interior boreal forest: that larger fires burn more severely than smaller fires, that wildfires burning during anomalously warmer and drier conditions burn at higher severity, and that more recent wildfires have burned more severely as compared to wildfires in the 1980s and 1990s. Findings refute previously stated assumptions. Fires that were smaller and burned under cooler, wetter conditions burned more severely than fires that were ultimately larger and burned under hotter and drier conditions.;The third paper explores the role of climate and vegetation composition on fire regimes in the Alaskan interior boreal forest. An analysis of vegetation burned from 2002--2008 indicated that there are likely multiple fire regimes in interior Alaska, instead of the single boreal forest regime that has often been described. Together, the three manuscripts identify methods for and avenues for further quantification and characterization of fire regimes in Alaskan landscapes.