Hypericum cuculicola demography in unoccupied and occupied Florida scrub patches with different time-since-fire

Metapopulation models predict that unoccupied, but suitable, patches will exist for species subject to extinction and colonization dynamics. We compared the demographic responses of Hypericum cumulicola, a rare herbaceous species almost entirely restricted to Florida rosemary scrub, when transplanted to occupied or unoccupied patches. Seedlings were transplanted and seeds buried into Florida rosemary scrub patches differing in time since last fire, and in the presence or absence of H. cumulicola. We used a replicated, factorial design to place the transplants and seeds in the field, and monitored their performance for 18 months. Neither time-since-fire nor prior H. cumulicola site occupancy affected survival of transplants. Only time-since-fire affected growth. Time-since-fire, H. cumulicola occupancy, and their interaction affected reproductive effort, but these effects were not consistent between years. Flowering and seed production led to subsequent seedling recruitment near transplants, mainly in recently burned sites. Genetic screening of transplants and seedlings showed that transplants in occupied sites could have crossed with nearby resident plants, but that offspring in sites previously unoccupied were likely to have been parented only by nearby transplants. Seeds buried, and later exhumed, germinated after 1 or 2 years of burial, demonstrating a persistent soil seed bank from which populations could recover after fire. Neither time-since-fire nor H. cumulicola occupancy affected seed dormancy or germination. Similar demography in unoccupied and occupied patches suggests that the patchy pattern of site occupancy by H. cumulicola is probably due to limited dispersal and periodic extinction, especially associated with long fire-free intervals. Conservation measures need to protect unoccupied patches to allow metapopulation dynamics and persistence.