Implications of managing the timing and intensity of herbivory for conservation of Arizona leatherflower

Abstract

For rare plants, the question of whether and to what extent wild and domestic herbivores influence growth, reproduction, and survival can be critical to preservation. The sensitive species, Clematis hirsutissima var. arizonica, grows on Forest Service lands where cattle, elk, mule deer, and numerous small mammals forage. In a 3-year clipping experiment, I examined the impact of season and intensity of herbivory on reproduction and growth. Vegetative reproduction was not influenced by year, season, or intensity of herbivory; however, sexual reproduction was influenced by year and season of herbivory. Spring-clipped plants produced significantly fewer seeds than mid or late-season clipped plants in 1996 and 1997. Once clipped in the spring, plants had reduced seed set in subsequent years. Natural levels of herbivory were significantly higher on unprotected than caged plants, especially when cattle were present. Unprotected plants tended to produce fewer flowers but differences were not significant. Overall sexual reproduction was very low in the light-limited study site. Conserving northern Arizona populations will require limiting detrimental early season activities, such as grazing and controlled bums, and increasing understory light reception.

Parent Publication

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

Citation

Maschinski, Joyce. 2001. Implications of managing the timing and intensity of herbivory for conservation of Arizona leatherflower. 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. 128-138.