Understanding the drivers and impacts of Appalachian fire regimes

SUMMARY: Appalachian fire regimes are as rich and complex as its forests. This research addresses the landscape pattern of where fires have occurred and their societal and ecological consequences. Concerns about impacts and the risks of wildfire have recently been heightened, in the southern Appalachians in particular, by the historic fall 2016 wildfire season. During the months of October and November, over 140,000 acres burned from over a dozen large fires on federal lands alone. While numerous fires exposed mountain residents to unhealthy smoke for weeks, the 2016 fall fire season ended with the loss of 14 lives and thousands of homes when the Chimney Tops 2 Fire burned Gatlinburg, Tennessee, and surrounding communities.

The fall of 2016 brought extreme drought that fed these fires, and while comparable droughts have happened before, their consequences in the form of wildfire were not so extraordinary within living memory. As was normal, the majority of 2016’s fires resulted from human ignitions, and this characteristic of the region’s fire regime makes climate-fire predictions more complicated than the standard wildfire narrative that has developed from experiences in the western United States. In the East, wildfire depends not just on drought and fuel conditions, but on erratic fire starts from both accidental and deliberate (arson) activity. While lightning fires do occur in the Appalachians, they are largely confined to the summer months when fire spread is checked by the relative high humidity from the forest canopy conditions and other seasonal climate factors. Together, the predominance of human ignitions, fuels fragmented by development, the importance of controlled burns for managing risks, and the constraints of the Wildland Urban Interface make Appalachian fire regimes at their core a human phenomenon. Understanding exactly how climate change fits into this dynamic is a key research need. Just how much of the fire impact from extreme drought can society prevent and mitigate in the Appalachians?

This research is inherently landscape in scale and multi-decadal in scope. These broad-scale, long-term perspectives provides context while efficiently producing results that are broadly applicable by agencies and local planners. From a “map” perspective, research documents the changing “fire footprint” in the landscape related to existing patterns of ownership, topography, vegetation, and fuels. This can help reveal what areas tend to burn, how fires can be better managed, and where the greatest conflicts lie. This knowledge can improve risk assessments, help prioritize fire prevention, and lead to more effective fuels management. With this project’s long-term perspective, researchers will gain a more accurate understanding of how vegetation and fuels are changing, how variation in the growing season and seasonal weather shifts wildfire risks, and whether there are trends in human behavior or land use that affect the character of tradeoffs.

According to eastern forest managers, the most basic fire-associated needs are to accurately understand changes in vegetation composition, structure, and fuels, yet current monitoring provides only a coarse understanding of fire impacts and the successional consequences of its exclusion. Existing maps of fuels regularly under-predict hazardous ericaceous shrub fuels prior to wildfire, and satellite-based fire severity products under-predict impacts of wildfire or controlled burns below the canopy. Small canopy gaps are also important, but under-tracked by monitoring systems. To improve on this, one aspect of this research explores the value of cross-seasonal remote sensing to monitor immediate fire effects and post-fire recovery. Combined with LiDAR-based maps of forest structure, this research will provide managerially important insights into how Appalachian forest structure and fuels have changed.

EFETAC'S ROLE: This project is supported by EFETAC research.

STATUS: Ongoing

PROGRESS: Research is ongoing with preliminary results presented to managers and researchers.

CONTACT: Steve Norman, EFETAC Research Ecologist, steve.norman@usda.gov or (828) 259-0535

Updated February 2017

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