Lakela’s mint, Dicerandra immaculata Lakela var. immaculata(Lamiaceae), is a critically endangered short-lived perennial that is known only from scrub habitat along a 4.8 km length of the Atlantic Coastal Ridge in Indian River and St. Lucie Counties, FL. The five remaining populations continue to decline in size. As part of efforts to conserve this species, we have augmented an existing population with individuals propagated in a greenhouse and monitored the augmented and wild populations yearly for 10 years. We analyzed the demographic data from a wild population and an augmented population to answer the following questions: 1) are these populations viable despite expected changes in climate; and 2) are augmented populations a viable conservation strategy? We used integral projection models to assess population viability. We incorporated past weather data into our models to assess the predictive power of temperature and precipitation in survival, growth, and fecundity. Also, we tested models with constant climate predictions against those that incrementally changed according to predictions for the region.
Results/Conclusions
Growth in Lakela's mint was most closely tied to minimum monthly temperatures and precipitation in-between demographic surveys, whereas reproductive output was most closely tied to maximum temperature prior to a survey. Population stability differed between study sites, and models predict that populations consisting of individuals augmented from ex situ material were less viable than the wild population. The predicted warming for eastern Florida may destabilize populations due to decreased survival, but increased reproductive output may partially offset those losses. Augmentations will likely continue to be necessary to conserve this species, since few wild populations remain. However, conservation efforts should include a sufficient number of augmented and introduced populations to offset predicted impacts of climate change.