Megan Daniluk

Deforestation is one of the most imminent threats that our planet faces today, as human caused alterations have affected 70% of the Earth’s surface. This removal of natural vegetation causes fragmentation for native plant and animal species, creating isolated spaces without the necessary nutrients for survival. One of the most threatened ecosystems is the tropical dry forest; however, recent conservation efforts in South America have allowed secondary forests to emerge in these spaces. One of the main factors that determines how these forests are restored is the mechanisms of seedling dispersal. The goal of this paper was to test a theory put forth by Daniel Janzen in previous literature about how the primary seed dispersal mechanism of a sucessional forest changes over time. A variety of plant traits, namely dispersal syndrome and stand age, were measured from 86 plots across three forest types in Sector Santa Rosa, located in the Area de Conservacio´n Guanacaste and Parque Nacional Palo Verde located in the Area de Conservacio´n Tempisque in Northwestern Costa Rica. These traits were analyzed to determine how abundance of trees distributed via specific seed dispersal mechanisms can be predicted over time. We found that in early successional stages in these forests, seeds are more often dispersed via wind into open spaces and more often dispersed by animals in later successional stages as there is more vegetation cover present. These findings were the most significant overall in the Santa Rosa dry forest (p < 2.2e-16). These results helpful in understanding the processes of secondary forest regeneration and aid in improving models of succession in these environments.