Population ecology of a sandhill endemic shrub, Ceratiola ericoides (sandhill rosemary)
Schmidt, John Paul
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Ceratiola ericoides (sandhill rosemary) is a dioecious, wind-pollinated, evergreen shrub adapated to the xeric, fire-adapted communities of the Southeast. 1. Spatial pattern of males and females in C. ericoides was investigated. Ripley’s K was used to analyze the spatial pattern of mapped populations of C. ericoides, and whether they exhibited spatial segregation of sexes (SSS). Results provide little evidence of SSS in this species. 2. Optimal fire frequency for C. ericoides was also investigated. Bayesian methods were employed to derive populations parameters from data collected in the field and from air-photos over a four-year period. Under the Bayesian approach, every parameter has a probability distribution rather than a fixed value. Results of Bayesian analyses of demographic data suggest that that increasing female distance from male significantly reduced realized female fecundity; both mortality and fecundity were higher on burned sites; shrub survivorship significantly increased with distance from longleaf pine on burned sites. These data were used to parameterize a stochastic individual-based model of C. ericoides population dynamics. Results suggest that a 20 year fire return cycle is optimal for C. ericoides, but that stochastic fire return intervals between 3 and 20 years result, on average, in population increases.