Recruitment success of native plant species is central to restoration of imperiled habitat. Restoration of the Archbold Reserve, a previously agricultural property adjacent to Archbold Biological Station on the Lake Wales Ridge, provides a unique opportunity to compare factors influencing seed availability and establishment of Florida scrub plants in native and disturbed scrub. We evaluated effects of habitat type on seed production and effects of habitat, microsite type and seed density on seed predation and establishment in two native scrub species: Chamaecrista fasciculata and Balduina angustifolia. Native and disturbed scrub differ in habitat structure and microsite abundance and distribution. Disturbed scrub has overgrown shrubs and extensive bare sand areas. Because habitat characteristics in the disturbed scrub may reduce competition with shrubs and provide larger habitat for recruitment, we expected that the study species would have higher seed production and seedling establishment in the disturbed scrub. We evaluated a range of seed densities to assess their effect on seedling recruitment. We hypothesized that seed removal would differ in the two habitats and among microsites due to potentially different suites of predators. We expected higher seed densities to further increase animal-mediated seed removal.
Results/Conclusions
Average individual seed production per site was not significantly different between habitats for both species, but there were differences among sites. However, a larger number of plants resulted in a greater head/pod density in disturbed scrub for both species: 1.03 heads/m2 in disturbed scrub vs. 0.12 seed heads/m2 in native scrub for B. angustifolia, and 1.75 pods/m2 in disturbed scrub vs. 0.05 seed pods/m2 in native scrub for C. fasciculata. Seed predation increased with seed density for C. fasciculata, but not for B. angustifolia. C. fasciculata germination and establishment were higher in disturbed scrub, where germination was higher under shrubs. Seed density increased germination and establishment in both habitats. B. angustifolia germination and establishment were greatest in native scrub, in bare sand and with higher seed densities. Our results suggest that habitat heterogeneity and seed availability influence recruitment with potential consequences for species persistence and successful reintroduction of scrub species.