title: Quantifying the human influence on fire ignition across the western USA.
abstract: Humans have a profound effect on fire regimes by increasing the frequency of ignitions. Although ignition is an integral component of understanding and predicting fire, to date fire models have not been able to isolate the ignition location, leading to inconsistent use of anthropogenic ignition proxies. Here, we identified fire ignitions from the Moderate Resolution Imaging Spectrometer (MODIS) Burned Area Product (2000-2012) to create the first remotely sensed, consistently derived, and regionally comprehensive fire ignition data set for the western United States. We quantified the spatial relationships between several anthropogenic land-use/disturbance features and ignition for ecoregions within the study area and used hierarchical partitioning to test how the anthropogenic predictors of fire ignition vary among ecoregions. The degree to which anthropogenic features predicted ignition varied considerably by ecoregion, with the strongest relationships found in the Marine West Coast Forest and North American Desert ecoregions. Similarly, the contribution of individual anthropogenic predictors varied greatly among ecoregions. Railroad corridors and agricultural presence tended to be the most important predictors of anthropogenic ignition, while population density and roads were generally poor predictors. Although human population has often been used as a proxy for ignitions at global scales, it is less important at regional scales when more specific land uses (e.g., agriculture) can be identified. The variability of ignition predictors among ecoregions suggests that human activities have heterogeneous impacts in altering fire regimes within different vegetation types and geographies.
authors.affiliation: Organismic and Evolutionary Biology Program, University of Massachusetts-Amherst, Amherst, Massachusetts, 01003, USA.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Fusco
authors.affiliation: Department of Geography, University of Idaho, 875 Perimeter Drive, MS 3021 Moscow, Idaho, 83844-3021, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Abatzoglou
authors.affiliation: Department of Geography, University of Colorado-Boulder, Boulder, Guggenheim 110, 260 UCB Colorado, 80309-0260, USA.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Balch
authors.affiliation: Organismic and Evolutionary Biology Program, University of Massachusetts-Amherst, Amherst, Massachusetts, 01003, USA.|Department of Environmental Conservation, University of Massachusetts-Amherst, 160 Holdsworth Way Amherst, Massachusetts, 01003, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Finn
authors.affiliation: Organismic and Evolutionary Biology Program, University of Massachusetts-Amherst, Amherst, Massachusetts, 01003, USA.|Department of Environmental Conservation, University of Massachusetts-Amherst, 160 Holdsworth Way Amherst, Massachusetts, 01003, USA.
authors.forename: Bethany A
authors.initials: BA
authors.lastname: Bradley
mesh_terms: D000383:Agriculture; D003247:Conservation of Natural Resources; D065928:Forests; D006802:Human Activities; D006801:Humans; D014481:United States
keywords: 
  MODIS
  ; MCD45A1; anthropogenic; fire; ignition; lightning; remote sensing; western USA