Cost of Reproduction and Artificial Defoliation in Aplectrum hyemale (Orchidaceae)
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Reproductive costs represent a common life history trade-off in plants. When combined with other stressors like deer herbivory, reproduction can lead to declines in growth, future reproduction, and survivorship. We examine the cost of herbivory and reproduction in Aplectrum hyemale, perennial deciduous forest herb with a unique phenology. A single leaf emerges in early fall, photosynthesizes through the winter, and senesces in spring as the canopy closes. Populations are often small and highly fragmented, making them vulnerable to stochastic processes. We conducted a defoliation experiment to determine how tissue loss and reproduction affect growth rates. We predicted that defoliated plants would exhibit lower growth rates than control plants, with plants defoliated shortly after shoot emergence exhibiting the greatest declines in growth. We also predicted that reproductive plants would have lower growth rates than non reproductive plants. We tagged plants and assigned them to four treatments: control, defoliation shortly after emergence, defoliation midway through the season, and defoliation prior to leaf senescence. To examine the cost of reproduction we grouped plants into two groups: flowering and non-flowering. We used ANCOVA to analyze how defoliation and reproduction affect relative growth rate (RGR) of shoots. Leaf area was our covariate.
& Rooney, T. P.
(2009). Cost of Reproduction and Artificial Defoliation in Aplectrum hyemale (Orchidaceae). Ecological Society of America Annual Meeting.