Post-fire cohort demography of Florida rosemary, a foundation shrub in Florida scrub

Background/Question/Methods

Florida rosemary (Ceratiola ericoides) is a foundation species, affecting the structure and function of Florida scrub by creating open gaps through strong competition and allelopathy. Existing research on the ecology and demography of Florida rosemary has primarily focused on its interactions with other species, comparative studies at a single time, and on existing stands of adult plants. The recruitment, survival and growth rates of younger plants in particular have not been much addressed. From 1996 to the present, we have studied the demography of post- fire seedling cohorts in six populations on Archbold Biological Station. We initiated the study of each of the six populations in a different year from 1996 to 2011. Each year in February, we recorded annual survival, height, length, width, and gender (when reproductive) for all plants.

Results/Conclusions

Florida rosemary seedling recruitment was closely tied to fire, peaking at two years post-fire and not continuing beyond five years post-fire. Annual survival was very high (usually above 98%). Survival increased sharply over the first few years of plant life and then approached an asymptote through 14 years of age (the length of our dataset); annual survival was well-described by a non-linear function. Growth in height and other linear dimensions was approximately linear and varied among populations. Reproduction occurred as early as four years of age, varied among populations, and appeared to occur earlier for male than female plants. Quantification of Florida rosemary demography can be used to better understand post-fire dynamics of subordinate, endangered herbaceous species, because their success depends upon growing in gaps at distances from Florida rosemary. Management for these endangered plants can be fine-tuned by understanding rosemary demography in relation to fire management.