Metapopulation dynamics of amphibians using isolated, ephemeral ponds in longleaf pine uplands

Several species of southeastern amphibians completely or facultatively depend upon small, ephemeral isolated ponds for reproduction, and inhabit surrounding uplands for much of their adult lives. However, spatio-temporal dynamics of pond use is little known. Since 1994, eight ephemeral ponds embedded within frequently (n=4) or infrequently (n=4) burned longleaf pine uplands in the Ocala National Forest, Florida, have been continuously sampled for herpetofaunal use. Drift fences were spaced to encircle 50% of each pond. Pitfall and funnel traps were positioned to detect directional movement to and from ponds. Breeding attempts and success was highly variable among species, ponds and years. Although patterns cannot be determined in four years, some trends in reproductive output were observed. Some species are produced in enormous quantities every few years, and from a fraction of available ponds (spadefoot toads, Scaphiopus ho/brook@ Others are produced in moderate numbers more consistently among years and ponds (leopard frogs, R. utricularia and Florida gopher frogs, R. capita). Yet others produce in smaller numbers every few years, and only from a few of seemingly available ponds. Apparently complex interactions between abiotic factors (weather, hydroperiod), underwater interactions (competition, predation) that vary among ponds, and life history traits result in complex local metapopulation dynamic6 that differ among species. Clearly, multiple isolated, ephemeral ponds within a landscape may be required to maintain amphibian populations in longleaf pine-wiregrass sandhills.