AUTHOR=Wilder Benjamin T. , Jarnevich Catherine S. , Baldwin Elizabeth , Black Joseph S. , Franklin Kim A. , Grissom Perry , Hovanes Katherine A. , Olsson Aaryn , Malusa Jim , Kibria Abu S.M.G. , Li Yue M. , Lien Aaron M. , Ponce Alejandro , Rowe Julia A. , Soto José R. , Stahl Maya R. , Young Nicholas E. , Betancourt Julio L. TITLE=Grassification and Fast-Evolving Fire Connectivity and Risk in the Sonoran Desert, United States JOURNAL=Frontiers in Ecology and Evolution VOLUME=9 YEAR=2021 URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2021.655561 DOI=10.3389/fevo.2021.655561 ISSN=2296-701X ABSTRACT=
In the southwestern United States, non-native grass invasions have increased wildfire occurrence in deserts and the likelihood of fire spread to and from other biomes with disparate fire regimes. The elevational transition between desertscrub and montane grasslands, woodlands, and forests generally occurs at ∼1,200 masl and has experienced fast suburbanization and an expanding wildland-urban interface (WUI). In summer 2020, the Bighorn Fire in the Santa Catalina Mountains burned 486 km2 and prompted alerts and evacuations along a 40-km stretch of WUI below 1,200 masl on the outskirts of Tucson, Arizona, a metropolitan area of >1M people. To better understand the changing nature of the WUI here and elsewhere in the region, we took a multidimensional and timely approach to assess fire dynamics along the Desertscrub-Semi-desert Grassland ecotone in the Catalina foothills, which is in various stages of non-native grass invasion. The Bighorn Fire was principally a forest fire driven by a long-history of fire suppression, accumulation of fine fuels following a wet winter and spring, and two decades of hotter droughts, culminating in the hottest and second driest summer in the 125-yr Tucson weather record. Saguaro (