Human Related Ignitions Increase the Number of Large Wildfires across U.S. Ecoregions

Transcription

1 Supplementary Materials for Human Related Ignitions Increase the Number of Large Wildfires across U.S. Ecoregions R. Chelsea Nagy, Emily Fusco, Bethany A. Bradley, John T. Abatzoglou, Jennifer Balch Correspondence to: This file includes: Table S1; Figure S1 S8.

2 Table S1. Summary statistics of large fires by Level III ecoregion. Level I ecoregion codes: NAD = North American Deserts, MED = Mediterranean California, SSH = Southern Semi Arid Highlands, TS = Temperate Sierras, TWF = Tropical Wet Forests, NF = Northern Forests, NFM = Northwestern Forested Mountains, MWC = Marine West Coast Forests, ETF = Eastern Temperate Forests, GP = Great Plains. Level III Ecoregion Name Number of large fires Mean large fire size (ha) Median large fire size (ha) Minimum large fire size (ha) Maximum large fire size (ha) Northern Basin and Range NAD Snake River Plain NAD Nebraska Sand Hills GP Canadian Rockies NFM Idaho Batholith NFM Central Basin and Range NAD Columbia Plateau NAD Southwestern Tablelands GP Chihuahuan Desert NAD North Cascades NFM Southern Florida Coastal Plain TWF Madrean Archipelago SSH Mojave Basin and Range NAD Flint Hills GP Edwards Plateau GP Blue Mountains NFM Southern and Baja California Pine Oak Mountains MED High Plains GP Northwestern Great Plains GP Middle Rockies NFM Arizona/New Mexico Mountains TS Klamath Mountains NFM Western Gulf Coastal Plain GP Wyoming Basin NAD Wasatch and Uinta Mountains NFM Southern Rockies NFM Lake Manitoba and Lake Agassiz Plain GP Cross Timbers GP Sierra Nevada NFM Level I Ecoregion Code

3 California Coastal Sage, Chaparral, and Oak Woodlands MED Northern Minnesota Wetlands NF Northwestern Glaciated Plains GP Central Great Plains GP Southern Texas Plains/Interior Plains and Hills with Xerophytic Shrub and Oak Forest GP Columbia Mountains/Northern Rockies NFM Eastern Cascades Slopes and Foothills NFM Colorado Plateaus NAD Arizona/New Mexico Plateau NAD Central Appalachians ETF Arkansas Valley ETF Southern Coastal Plain ETF Cascades NFM Ouachita Mountains ETF Central Irregular Plains GP Sonoran Desert NAD Chihuahuan Deserts NAD Boston Mountains ETF Central California Valley MED Aspen Parkland/Northern Glaciated Plains GP Ozark Highlands ETF Western Corn Belt Plains GP Southwestern Appalachians ETF East Central Texas Plains ETF Mississippi Alluvial Plain ETF Middle Atlantic Coastal Plain ETF Interior River Valleys and Hills ETF Blue Ridge ETF Eastern Corn Belt Plains ETF Northern Lakes and Forests NF South Central Plains ETF Ridge and Valley ETF Central Corn Belt Plains ETF Mississippi Valley Loess Plains ETF Coast Range MWC Texas Blackland Prairies GP

4 Western Allegheny Plateau ETF Southeastern Wisconsin Till Plains ETF North Central Appalachians NF North Central Hardwood Forests ETF Interior Plateau ETF Southeastern Plains ETF Southern Michigan/Northern Indiana Drift Plains ETF Huron/Erie Lake Plains ETF Atlantic Coastal Pine Barrens ETF Willamette Valley MWC Driftless Area ETF Piedmont ETF Acadian Plains and Hills ETF Northern Appalachian and Atlantic Maritime Highlands NF Northern Piedmont ETF Strait of Georgia/Puget Lowland MWC Erie Drift Plain ETF Northern Allegheny Plateau ETF Northeastern Coastal Zone ETF

5 (a) 1

6 (b) Figure S1. (a) Map of Level III U.S. Ecoregions from the Center for Environmental Cooperation (2006) and (b) key to ecoregion numbers in map shown in (a). 2

7 Figure S2. Grouping of U.S. Level III ecoregions into the eastern and western U.S. for discussion of regional trends. Figure S3. LANDFIRE Biophysical Settings (vegetation classes) of the continental U.S. 3

8 Figure S4. Percent of large fires caused by humans defined as the (a) top 5 percent and (b) top 20 percent of largest fires by ecoregion: Humans are the dominant source of large fires in ecoregions of the eastern U.S. and the west coast. Normalized burned area of large human-caused fires Figure S5. Total burned area (ha) of large human caused wildfires of each ecoregion divided by the area (ha) of the ecoregion. Difference in Median DOY H: days earlier H: days earlier < 20 days difference H: days later H: days later Figure S6. The difference in median Julian day of year (DOY) for large human caused wildfires vs. large lightning caused wildfires by ecoregion. The difference shown is the human median DOY (H) relative to the lightning median DOY (L). Ecoregions colored in white had zero large lightning caused wildfires. 4

9 Large fires outside of lightning season ,000 10,000-18,282 Figure S7. The number of large wildfires that occurred outside of the fire season for large lightningcaused wildfires (i.e. before the 2.5 th or after the 97.5 th percentiles of day of year; April 13 th and September 24 th, respectively) by ecoregion; totaling 80,896 large wildfires. (a) 5

10 (b) Figure S8. Number of large wildfires by ecoregion in bins of annual 100 hr fuel moisture (%) vs. wind speed (m s 1 ) data extracted by fire event for only the large wildfires (10% of largest wildfires by ecoregion) for (a) human started large wildfires (n=142,276) in gray red and (b) lightning started large wildfires (n=32,946) in gray blue. 6