Most of the original global extent of tropical forests has been lost to deforestation caused by anthropogenic disturbances and changes in land use. Even while human-modified landscapes are increasing in area throughout the tropics, the dynamics, drivers, and outcomes of successional processes in tropical forests remain poorly understood. The arrival of tree species during forest regrowth begins with seed dispersal followed by seedling establishment, which are key processes in forest regeneration as they determine colonization of deforested areas that establish initial conditions for secondary successional trajectories. In human-modified landscapes, seed dispersal can be disrupted in many ways.  For example, animal dispersal services can be reduced because their movements can be impeded in fragmented landscapes, and their populations may be reduced by hunting.  Dispersal may be disrupted for abiotically dispersed species as well, as many seeds will fall in inhospitable recruitment sites, causing recruitment limitation.  Sources of seeds may be rare on the landscape or represent a subset of the former diversity that was present pre-fragmentation. These and other local and landscape factors operate to reduce seed arrival or alter the composition of the seed rain into forest, with consequences for forest regeneration during succession. The proposed Symposium aims to integrate results from successional forests in order to characterize how local and landscape factors affect seed dispersal in human-modified landscapes and their consequences for forest regeneration. 

These local and landscape factors can have variables effects on seed dispersal across the different geographical scales and successional stages (early, mid, and late-successional sites). This variation will arise because these factors have their greatest effects at different successional stages and tree species. As a result, some tree species are favored over others in a singular successional stage, which will influence the trajectory of forest composition and structure across succession in these human-modified landscapes. 

The research to be presented in this Symposium will assess the importance of local and landscape factors on seed dispersal in tropical forests.  By examining specific responses by successional forest stages or tree species, the Symposium will analyze the potential challenges on the regeneration of human-modified landscapes. The Symposium will close with an interactive panel discussion moderated by the organizers and including the Symposium speakers to consider these challenges and how they can be addressed given current frameworks for research and conservation.

Photo: Sabrina E. Russo