Research Highlights

Human Influence on California Fire Regimes

Abstract: Periodic wildfire maintains the integrity and species composition of many ecosystems, including the mediterranean-climate shrublands of California. However, human activities alter natural fire regimes, which can lead to cascading ecological effects. Increased human ignitions at the wildland-urban interface (WUI) have recently gained attention, but fire activity and risk are typically estimated using only biophysical variables. Our goal was to determine how humans influence fire in California and to examine whether this influence was linear, by relating contemporary (2000) and historic (1960-2000) fire data to both human and biophysical variables. Data for the human variables included fine-resolution maps of the WUI produced using housing density and land cover data. Interface WUI, where development abuts wildland vegetation, was differentiated from intermix WUI, where development intermingles with wildland vegetation. Additional explanatory variables included distance to WUI, population density, road density, vegetation type, and ecoregion. All data were summarized at the county level and analyzed using bivariate and multiple regression methods.

Syphard AD, Radeloff VC, Keeley JE, Hawbaker TJ, Clayton MK, et al. (2007) Human Influence on California Fire Regimes. Ecological Applications: Vol. 17, No. 5 pp. 1388-1402. Available online at the Ecological Society of America Journal website.

Issue cover and text from the website October, vol. 18, No. 7): A headwater stream draining corn fields and pastures of a dairy farm in southwestern Wisconsin (USA). Stanley et al. study how row-cropping, livestock grazing, and limited riparian protection are common in agricultural areas, and in turn, how agricultural land use is associated with nitrogen hypersaturation in many of the state's streams and rivers (see pp. 1579-1590). Photo credit: Matt Diebel