Population viability analysis and the effects of light availability and litter on populations of Cirsium pitcheri, a rare, monocarpic perennial of Great Lakes shorelines

• Published in: Biological conservation 2015-07, Vol.187, p.82-90
• Main Authors: Jolls, Claudia L., Marik, Julie E., Hamzé, Samara I., Havens, Kayri
• Format: Article
• Language: English
• Subjects: Cirsium pitcheri; Dune succession; Elasticity analysis; Emergence; Litter; Pitcher’s thistle; Plants (organisms); Population growth; Population viability; Rare plant conservation; Recruitment; Simulation; Viability; Wildlife conservation
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2015.04.006

[Display omitted] •We model the impact of succession and invasive plants on a rare dune endemic.•Elasticity analyses show the importance of seed and seedling success.•Shading and litter reduced population growth and time to extinction.•During the 19year study period, only four years showed growth for this population.•Control of invasives and populations linkages are important for species persistence. An understanding of plant population dynamics in response to natural and anthropogenic influences is critical for rare species management. We present a long-term study and population viability analysis of a federally threatened monocarpic, Cirsium pitcheri, endemic to the Great Lakes, in northern Michigan. Population growth rates of C. pitcheri were highly variable; only four of the 14year-pairs studied during the 19yr study period indicated a growing population (λ>1). Elasticity analysis showed population growth was sensitive to seedling recruitment. We manipulated light and litter levels in the growth chamber to simulate natural succession or invasive plants and to determine their effects on seedlings and ultimately, population performance. The absence of shading and litter increased seedling emergence from 8% to 42%, but no simulated population had less than a 5% risk of extinction over a 25-year period. These populations are, strictly speaking, non-viable. Population viability and conservation of this species are linked to recruitment, including seedling success. Control of plant and animal invasive species and addition of greenhouse transplants to increase recruitment may help reverse population declines.