Why do large fire years often follow one or more wet years in the semiarid Great Basin?

Many semi-arid communities are fuel limited, thus the accumulation of fine fuels during wet years increases fuel continuity at the landscape level and has been closely linked to large and widespread fires in semiarid ecosystems (Abatzoglou and Kolden 2013; Allen et al. 1995; Baisan and Swetnam 1997; Brown et al. 2008; Grissino-Mayer and Swetnam 2000; Miller and Rose 1999; Swetnam and Betancourt 1998). 

The 2007 Milford Flat fire in Utah burned over 500 square miles of cheatgrass, sagebrush and woodland, the same year the Murphy complex fire burned 1,000 square miles in Idaho. The year 2007 was preceded by two excellent growing seasons in the Intermountain West resulting in an accumulation of fine surface fuels (Photo Milford Flat fire UT, by Rick Miller Oregon State University).