Empirical Characterization of Fire Regimes Across the Globe

Friday, December 14, 2018 - 08:00
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Climate conditions, vegetation, fuel type and availability govern the occurence and behavior of fires. Understanding the seasonality, frequency, intensity, and severity of fires is critical for land managers to appropriately manage and plan the landscape and to understand the feedbacks to the Earth system. Fire Regimes are conceptually useful to land managers and are qualitatively understood, but few quantitative techniques exist for empirically delineating geographic regions whose wildfire spatial and temporal characteristics, re-visitation frequency, and intensities are similar.

We consider the extensive and consistent thermal “hotspot” data which are collected globally by the two MODIS sensors during their 17-year orbital history. Such ubiquitous remote sensing data provide an opportunity to produce a quantitative discrimination of different global fire regimes, including tele-connections across hemispheres. We do not filter or remove human-caused fires from wildfires, instead considering and classifying both types of fire regimes holistically. To appropriately address opposing seasonal juxtaposition across northern and southern hemispheres we developed a special transformation of fire dates which allows statistical identification and discrimination of, say, “summer” fires, regardless of the calendar month in which they occurred across the hemispheres. This date transform permits the recognition of similar fire regimes in both the northern and southern hemispheres. On the basis of about twenty descriptive fire characteristics, we produced a series of global maps at multiple levels of fire regime discrimination. By applying principal component analysis, we also visually quantify the degree of similarity among the different global fire regimes and quantitatively identify the characteristics responsible for the similarities or differences.

Geographically distant locations which share similar fire regime characteristics were found; many of these fire “tele-connections” span across different hemispheres. Regularly occurring human-caused Fire Regimes can also be easily identified globally. Locations sharing similar global fire regimes may have similar ecological effects and impacts from fire, and similar management knowledge and successful adaptation strategies might be borrowed, shared, or adopted.

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