EXAMINING THE PAST, PRESENT, AND FUTURE OF AN ICONIC MOJAVE DESERT SPECIES, THE JOSHUA TREE (YUCCA BREVIFOLIA, YUCCA JAEGERIANA)

Abstract The Joshua tree (Yucca brevifolia, Y. jaegeriana) is a large, evergreen monocot distributed patchily across the southwestern United States. The plant occurs on alluvial fans, plains, and bajadas primarily in the Mojave Desert, but populations can also be found in the Great Basin and Sonoran Deserts. Named by the Mormon pioneers for the branching, supplicating arms reaching toward the sky, the species has become an emblematic symbol of the Mojave Desert for residents and visitors alike. Joshua trees inhabit cooler, moister microclimates within the larger desert macroclimate, and research has indicated the species may be vulnerable to future climatic regimes characterized by warmer and drier conditions. Here we present a concise review examining the past distribution, the current population status and threats, and the viability of the species under differing habitat and climate scenarios projected for the future. Additionally, we identify knowledge gaps to guide future research directions. Our results provide insight into management and conservation actions and contribute to a greater understanding of range-wide effects of ongoing environmental change on this species.