DENSITY AND SEED PRODUCTION OF A FLORIDA ENDEMIC, POLYGONELLA-BASIRAMIA, IN RELATION TO TIME SINCE FIRE AND OPEN SAND

Density and reproductive output in relation to fire, open sand, and other site factors were determined for Polygonella basiramia. This federally endangered species is endemic to only three ridges in central Florida and found primarily in rosemary (Ceratiola ericoides) dominated sand pine (Pinus clausal scrub. Twenty-two sites ranging from 5 to >26 yr postfire were sampled. Site factors of openness, time since last fire, dominant species, ground cover, elevation and soil type were examined. Multivariate analyses identified the amount of open sand habitat at a site as the only variable having a significant positive relationship with both plant density and seed production. Seed production actually increased with conspecific density, suggesting that the lack of interspecific competition in open sand gaps helps define P. basiramia microhabitat. Open sand habitat is critical in the life history strategy of this obligate-seeding, perennial herb in a community where it must compete with larger, resprouting shrubs and herbs both immediately after fire and during fire-free intervals.