Mean annual temperature (MAT) at Zion National Park, Utah, has steadily increased since 1928 and will likely continue to increase as more carbon dioxide is added to the atmosphere (IPCC 2007a; Gonzalez et al. 2010) (fig. 1a, below, and figs. 1b and 1c). Climate projections for Zion suggest that mean annual temperature by 2100 may be higher on average than in any year in the last century, including the 1934 Dust Bowl. Natural variability ensures that the temperature trend will not be as linear as shown by projections in figure 1, but at broad scales the upward direction and magnitude are very likely (>90% probability), according to the most credible and widely accepted projections (IPCC 2007b). Projected changes in precipitation are less certain, with some scenarios indicating increase and others decrease. What effect these changes in climate might have on species distributions if the new “normal” exceeds anything we have seen in the last 100 years is of great interest to park managers. We examine this question by explicitly mapping potential habitat under climate change scenarios 100 years from now for three species of concern in Zion by following established guidelines for vulnerability assessments (Glick et al. 2011). These maps and the associated data are a first step toward developing the credible scientific underpinnings for park-level planning under the constraints and opportunities of climate change.
Figure 1. (A) Zion-centered study area with location of Zion National Park headquarters weather station (red star).
Climate is the most important driver of species distributions at broad scales, but other factors like species interactions, dispersal, and physical factors such as soil type influence species distributions at the local or park scale. As climate changes, species will adapt, migrate, or perish in response to both direct and indirect effects, but which are the most likely outcomes? That depends on species life history traits, availability of habitat in the future, and a host of other factors that we cannot predict with accuracy. However, mapping the intersection of important landscape parameters in and near parks and climate in relation to species distributions provides clues to help predict where suitable habitat may exist in the future.
Mapping the intersection of important landscape parameters in and near parks and climate in relation to species distributions provides clues to help predict where suitable habitat may exist in the future.
Habitat maps are integral to adaptation frameworks in order to plan courses of action that could include managing for resilience, resistance, and facilitated migration (Stephenson and Millar 2012). More immediate actions based on habitat maps could include negotiating land sales or conservation agreements to protect or link habitats. Collectively, these kinds of adaptation actions could provide time and space for species to adapt to new climates. Yet in spite of its importance for planning, predicting future habitat for specific organisms is an evolving science with considerable uncertainty.
The goal of this research was to use existing data, models, and information from subject-matter experts to map current and future potential habitat for selected species in Zion National Park as input to a vulnerability assessment. Our focus was on the potential future habitat of the threatened desert tortoise (Xerobates [Gopherus] agassizii), the endangered Shivwits milk-vetch (Astragalus ampullarioides), and the climate-sensitive American pika (Ochotona princeps) in and near Zion (fig. 1a, above).
Thoma, D., and H. Shovic. 2013. Using landscape patterns, climate projections, and species distribution models to map future potential habitats for desert tortoise, Shivwits milk-vetch, and American pika in Zion National Park, Utah. Park Science 29(2):14–22.
Available at http://www.nature.nps.gov/ParkScience/archive/PDF/Article_PDFs/ParkScience29(2)FallWinter2012-2013_1_14-22_ThomaShovic_3628.pdf.