Smooth Arizona Cypress and Piute Cypress

Fig. 1 - Modeled realized climatic niche
for Smooth Arizona Cypress

The predicted contemporary realized climatic niche space for smooth Arizona cypress and Piute cypress better described actual distributions than Little’s range map (Figures 1A, 2A). Although a few populations were not mapped in the realized climatic niche, we suspect that this omission was due to either a mapping resolution that was too coarse or to field locations that were not accurate enough.

Fig. 2 - Modeled realized climatic niche
for Piute cypress

In response to global warming, the realized climatic niche space of Arizona smooth cypress should shift about 200 to 350 km northwest of its contemporary location (Figures 1B, 1C, 1D). The area occupied should increase by about 1.5 and 2 times its contemporary size in decades 2030 and 2060, respectively (Table: Projected change in area of species). In decade 2090, the area decreases to 1.2 times the contemporary size as the distribution shifts to northern Nevada and southwestern Colorado. In all 3 future decades, the contemporary realized climatic niche space is expected to be prominent in valleys where the Arizona, Nevada, and Utah borders meet. This includes the Virgin Mountains in Nevada, an area where naturalized populations of the subspecies have been observed (Charlet 1996). Only 14 percent of the climate space is expected to remain in place in its contemporary location through the decade of 2030, and none is to remain in place for decades 2060 and 2090. By the end of the century, average elevation is projected to increase 611 m.

Fig. 3 - Predicted response for
Piute Cypress

By decade 2030, the Piute cypress realized climatic niche space will lie outside its contemporary distribution. The realized climatic niche space is projected to shift nearly 40 km to the east along the southeastern slopes of the Sierra Nevada (Figure 2B). Overall, the area of its distribution should shrink about 86 percent (Table: Projected change in area of species). Altitudes, however, should increase by about 100 m. The realized climatic niche space should also appear nearly 1100 km to the north near The Dalles, or by the decade of 2030 (Figure 1A) where it is projected to persist throughout the century (Figures 1B, 1C). In fact, by 2060, the realized climatic niche space of this subspecies occurs exclusively in Oregon and should occupy an area less than 90 percent of its contemporary distribution. The mean elevation for these new sites in Oregon and Washington are about 200 to 300 m lower in elevation than the contemporary distribution.