Extinction risk of Ipomopsis sancti-spiritus in Holy Ghost Canyon with and without management intervention

Abstract

Small populations are threatened with deterministic and stochastic events that can drive the number of individuals below a critical threshold for survival. Long-term studies allow us to increase our understanding of processes required for their conservation. In the past 7 years, the population of the federally endangered Holy Ghost ipomopsis (Ipomopsis sancti-spiritus) in Holy Ghost Canyon has fluctuated widely from 2047 to 372 plants. Metapopulation analysis of average Leslie matrices suggested that I. sancti-spiritus has a high probability of extinction; 60 percent of the demographic transects have negative growth rates. Transects with the greatest likelihood of remaining occupied, the highest h values, and the greatest source of new propagules for maintaining the species in Holy Ghost Canyon are in the sunny lower part of the canyon. In comparison, transects at the top of the canyon have fewer individuals and lower probability of remaining occupied. With management intervention to disperse propagules from more fecund to less fecund areas of the canyon, metapopulation modeling indicated decreased (but still a high) risk of extinction within the next 50 years. Thus, although seed augmentation and habitat improvement can improve the chances for I. sancti-spiritus persistence in Holy Ghost Canyon, the species remains at high risk of extinction.

Parent Publication

• Southwestern rare and endangered plants: Proceedings of the Third Conference

Citation

Maschinski, Joyce. 2001. Extinction risk of Ipomopsis sancti-spiritus in Holy Ghost Canyon with and without management intervention. In: Maschinski, Joyce; Holter, Louella, tech. eds. Southwestern rare and endangered plants: Proceedings of the Third Conference; 2000 September 25-28; Flagstaff, AZ. Proceedings RMRS-P-23. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 206-212.