Shrub Seedling Establishment is Limited by Dispersal, Slow Growth, and Fire in Two Wet Pine Savannahs in Mississippi

Abstract

Abstract 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 ...