Date of Award:
Master of Science (MS)
Eugene W. Schupp
Conservation and recovery plans for rare species require biological and ecological information to discern how they may be susceptible to human disturbances. Phacelia submutica is a threatened annual species in western Colorado. Human activities including energy development, recreation, and livestock grazing are occurring within the species’ range. To provide conservation practitioners with a scientific basis for management, this research aimed to elucidate elements of the species’ ecology. Chapter 2 describes the reproductive biology of P. submutica. Potential insect pollinators were not observed during two years of observations. Floral traits and development ensure self-pollination and reduce the likelihood that insects would be effective pollinators. Hand pollination experiments using varying pollen sources did not result in significant differences in seed number and mean mature seed weight per fruit, two metrics of reproductive success. These results indicate that the species is habitually autogamous. Conservation of this species will not require the protection of pollinators and their habitat, but should consider the potential impacts of autogamy on the species’ genetic diversity. Chapter 3 examines aspects of P. submutica’s seed ecology as they relate to the development and maintenance of the seed bank. Observations suggest seeds are limited in their long-range dispersal capacity. Average seed bank density was low (74 seeds per m2) and seeds were highly aggregated within sites. Based on three years of seed burial data, the species forms a long-term persistent seed bank that maintains high proportions of viability in drought years, but germinates prolifically in favorable years. Projections of seed depletion rates from this dataset predicted longevity to be between four and six years. Finally, seeds were generally unresponsive to germination trials involving varying degrees of cold-moist stratification, incubation temperatures, and scarification. P. submutica shows adaptations that promote its persistence in an arid environment characterized by climatic variability. Appropriate management of this species will require protection of the seed bank and the dynamics involved in its replenishment and maintenance. Chapter 4 presents implications of the two major studies and provides conservation practitioners with an integrated assessment of the results and how they relate to management.
Langton, Alicia M., "Factors Contributing to the Conservation of Phacelia submutica (Boraginaceae), a Threatened Species in Western Colorado: Reproductive Biology and Seed Ecology" (2015). All Graduate Theses and Dissertations. 4284.
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