WEEKLEY, CARL W.* and ERIC S. MENGES. Archbold Biological Station, PO Box 2057, Lake Placid, FL 33862. - Fire and Florida scrub: responses of 13 endemics and postburn community shifts.
We investigated the effects of prescribed fire on a long-unburned sand
pine scrub on central Florida’s Lake Wales Ridge. We quantified the
postburn survival of 13 endemic plant species by censusing tagged
individuals before and after prescribed fire and by comparing survival
of burned vs. unburned individuals. Ten of our study species were
herbs, two were woody shrubs, and one was a woody prostrate subshrub.
We assessed changes in the species composition and community structure
of the scrub ecosystem through pre- and postburn sampling of 12
100m2 plots. We also investigated the effect of changes in
community structure on overall herb abundance. We found that nine of
13 species had postburn resprouting rates varying from 15% to 98%.
Three species (Bonamia grandiflora, Nolina brittoniana
and Prunus geniculata) are strong resprouters (well over 50% of
burned plants resprouting); two species, Clitoria fragrans
(48.4%) and Liatris ohlingerae (47.3%), are intermediate
resprouters; four species (Asclepias curtissii, Garberia
heterophylla, Helianthemum nashii and Sisyrinchium
xerophyllum) are weak resprouters (>10% but <30%); and four
species (Paronychia chartacea ssp. chartacea,
Polygonella myriophylla, P. robusta and Schizachyrium
niveum) are killed by fire. Postburn reductions in subcanopy,
shrub, litter, lichen and P. myriophylla cover were paralleled
by increases in the frequency and abundance of scrub herbs (including
Lechea deckertii, Cnidoscolus stimulosus, Stipulicida
sectacea and Stylisma abdita). While overall species
richness decreased postburn, herb species richness increased. Although
some scrub herbs resprout, most postburn increases in herb abundance
were due to seedling recruitment.
Key words: endemics, fire, Lake Wales Ridge, scrub