Fire phenology and land use assessment in the eastern United States
SUMMARY: Wildland fire is both an indicator and a driver of environmental change. In the West, the effects of a changing climate on fire regimes have been well established, highlighting concerns that climate change can radically and rapidly alter ecosystems. In the East, climate-fire relationships are far from clear. Most eastern fires are not caused by lightning, but by accidental human ignitions and arson. As most eastern fires are relatively small in area compared to the West, the pattern of human ignition greatly limits which portions of the landscape experience fire. This is particularly remarkable because ecological and historical lines of evidence suggest that fires have been greatly reduced from their prior frequency even in remote areas and that more fire use in those areas is often necessary to keep forests resilient. Researchers are working to better understand fire across the landscape to effectively restore fire-dependent ecosystems and address future risks.
A first step to understanding climate-associated risks from fire is to document existing fire regimes using state and federal data sets. Due to the large number of agencies involved, eastern wildfire data are highly fragmentary, inconsistent, and incomplete. It is also more difficult to make sense of eastern fire data because patchy land ownership, fuel conditions, and a long-history of cultural fire use make it difficult to delineate which wildfires legitimately threaten forest values, which fires sustain forests, and which fires are unassociated with forests.
This project has two principal components: (1) to assemble historical wildland fire data from the various state and federal agencies for the eastern United States into a quality-controlled wildland fire database, and (2) to model fire regimes based on informational record quality, cause, land cover, seasonal vegetational attributes, and climate.
PROGRESS: Results indicate that the eastern fire season is sensitive to regional year-to-year variation in regional climate and global sea surface temperatures, and to variation in the timing of leaf greenup and leaf loss (land surface phenology derived from MODIS satellite data). Leaf phenology, in turn, depends on broad-scale variation in climate and local forest compositional factors.
This suggests that in the future, eastern fire regimes may not only respond to summer drought stress or the length of the growing season, but to changes in the onset and duration of the open-canopied spring and fall fire seasons—these are controlled by both climate variation and forest composition. These effects are further nuanced by human ignition behavior and land cover change that involve choices that society makes. Despite the complexity of eastern fire regimes, certain social and forest management actions can mitigate some potentially undesirable effects of climate change.
CONTACT: Steve Norman, EFETAC Ecologist, email@example.com or 828-259-0535
Updated September 2010