Identifying the mechanisms that drive invasions of open habitats by woody species is critical for preserving diverse savannas. Trees can promote the establishment of bird-dispersed woody plant species in savannas by reducing dispersal limitation. Previous work in wet pine savannas has shown that densities of bird-dispersed shrubs are higher and species richness of herbaceous species, most of which are not bird-dispersed, is lower in areas near trees. To test the hypothesis that shrub seedling density in wet pine savannas was limited by dispersal and thus the availability of perches for seed-dispersing birds, seed traps and artificial perches were placed near and away from pines. To measure fire-induced mortality of trees and shrubs, Pinus elliottii juveniles and shrub seedlings that had emerged during a fire-free interval were quantified before and after fires. Trees provided perches for birds that dispersed shrubs, thereby reducing dispersal limitation of shrubs. Significantly more seeds of the shrubs, Ilex glabra and I. vomitoria, were encountered in seed traps at the bases of P. elliottii than in areas away from trees in two consecutive years. Seedlings of woody species with fleshy fruits occurred more frequently at the bases of artificial perches than away from perches, and the effect of the perches on seedling density was greater away from trees. Eight- and nine-year periods without fire were not long enough for the majority (>99%) of post-fire recruits of P. elliottii to grow large enough to survive growing-season fires. A small but greater fraction of shrub seedlings (10%) survived the fires. We argue that periodic fires are sufficient to preclude further invasion of wet pine savannas by P. elliottii, expansion of shrub thickets, and associated declines in plant diversity.