Graduation Date

Spring 2023

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources: option Environmental Science and Management

Committee Chair Name

Dr. Kerry Byrne

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Erik Jules

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Daniel Barton

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Environmental Science and Management

Abstract

As anthropogenic activities expand, conservation of rare and endangered species is critical to reduce extinction risks. Collecting and analyzing demographic data can assist in the development of conservation strategies and can help evaluate the success of existing strategies. In this study, I built integral projection models from five years of demographic data and conducted a population viability analysis on four populations of the rare perennial herb, Astragalus applegatei, to inform conservation decisions. I also assessed how planting A. applegatei seedlings might contribute to the growth of an extant population. I found that one population was already below the extinction threshold and another population is at-risk. Survival and growth rates of established individuals had the strongest influence on population growth across populations and were higher in populations near a persistent water source. In contrast, the highest fecundity rate was in the population with an existing mowing regime, but far from a water source. For planted individuals, 9.7% survived to the end of the study and were larger than extant individuals as they aged. Young, planted individuals also had a higher probability of flowering. This study suggests conservation strategies should target survival and growth rates of established individuals in all populations, while also lowering interspecific competition in populations with low fecundity rates. Furthermore, planted individuals recovered from the translocation process to support the extant population’s growth. This study contributes to the long-term persistence of A. applegatei by uncovering the factors influencing population fluctuations, and can be used as a model for other perennial herbaceous species.

Citation Style

APA

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