Fire response and population persistence in the endangered scrub lichen Cladonia perforata

Background/Question/Methods

Florida perforate reindeer lichen (Cladonia perforata) is a federally protected lichen endemic to Florida, preferring rosemary-phase sand pine scrub. Long-term monitoring of population persistence in C. perforata will be crucial to informing further conservation efforts and its status as an endangered species. From 2009 to 2022, we monitored the persistence of nine C. perforata subpopulations on the Lake Wales Ridge at Archbold Biological Station (n = 7) and the Royce Ranch Wildlife and Environmental Area (n = 2). In three-year intervals at each subpopulation, we checked for presence of C. perforata fragments within 3 m plots, while in a subset of plots we measured percentage ground cover using a lichen cover board. Lastly, we remapped each extant subpopulation every six years by marking the perimeter of lichen cover, allowing us to determine changes in overall spatial distribution over time. Due to the importance of fire ecology for C. perforata, we resurveyed within one month of any prescribed burns, and an experimental lichen removal prior to fire was also conducted.

Results/Conclusions

Most subpopulations of C. perforata decreased in size (cover) or remained relatively stable over time. C. perforata also appears to be fire-sensitive, with burned plots showing overall greater decreases in lichen cover compared to unburned plots. Importantly, removing C. perforata prior to fire yielded improvement in lichen cover compared to plots where it was not removed. Overall, these results highlight the importance of fire in mediating population dynamics of C. perforata. Patchy fires that leave rosemary scrub habitat gaps unburned are likely to promote the long-term persistence and abundance of C. perforata and other fire-sensitive ground lichen species. Temporary removal of lichen during burns may provide an additional management tool for preserving sensitive C. perforata subpopulations.