Distribution Data and Habitat Models for Joshua Trees (Yucca brevifolia and Y. jaegeriana) Throughout their Range

We delineated the existing empirical and modeled ranges of western and eastern Joshua trees (Yucca brevifolia and Y. jaegeriana, respectively) with high fidelity and across their ranges in Arizona, California, Nevada, and Utah, USA. Most species distribution models (SDMs) rely on sparse species occurrence datasets and random pseudoabsences. In contrast, the tall stature and distinctive branching arms of Joshua trees enabled us to definitively identify this species in publicly available satellite imagery, allowing us to use intensive visual grid searches to map empirical presences and absences at a 0.25 km2 resolution across most of the species’ ranges. These empirical mapping data were used to guide exceptionally accurate SDMs for each species. SDMs provide an opportunity to evaluate the current distribution of each species against key climate variables and assess the potential habitat of each species in relation to current empirical distributions. The two Joshua tree species occupy similar climate conditions relative to total aridity, yet seasonal precipitation and temperature conditions vary. Eastern Joshua tree has the potential to occupy a greater proportion of the current distribution of the western Joshua tree, while potential habitat for the western Joshua tree is less well represented across the current range of the eastern species. With the current range of both species well defined at high resolution, it is now possible to evaluate both species’ habitat vulnerabilities and potential refugia in relation to habitat loss and potential climate change.

These data support the following publication:
Esque, T.C., Shryock, D.F., Berry, G.A., Chen, F.C., DeFalco, L.A., Lewicki, S.M., Cunningham, B.L., Gaylord, E.J., Poage, C.S., Gantz, G.E. and Van Gaalen, R.A., 2023. Unprecedented distribution data for Joshua trees (Yucca brevifolia and Y. jaegeriana) reveal contemporary climate associations of a Mojave Desert icon. Frontiers in Ecology and Evolution, 11, p.1266892. https://doi.org/10.3389/fevo.2023.1266892