Dispersal is a critically important process for shaping ecological communities and ecosystems and is increasingly receiving attention as organisms and landscapes are affected by habitat fragmentation and climate change. Wind-dispersed organisms rely on organism traits, flow dynamics of air, and structural heterogeneity of landscapes for their dispersal. Landscape connectivity and structural heterogeneity can interact with wind dynamics to change the flow of air as well as the amount of turbulence and uplifting – two critical processes known to drive dispersal. We released artificial seeds from multiple locations simultaneously within an experimental landscape that manipulates connectivity (i.e., corridors) and patch shape to examine how landscape connectivity and heterogeneity affect wind dispersal. The landscape is composed of three patch types; connected (via a corridor), winged (unconnected with high edge-to-area ratio), and rectangular (unconnected with low edge-to-area ratio). Three-dimensional sonic anemometers and temperature/humidity loggers were deployed within the patches.
Results/Conclusions
We found that when above-canopy winds were aligned with corridors, seeds dispersed over much greater distances than in the absence of a corridor. When winds were more perpendicular to corridors, seed dispersal distances were much shorter. Within-patch comparisons revealed strong differences between center and edge releases, regardless of wind direction or speed aloft. Seed shadows within winged patches were much larger than those within rectangular patches. Seeds released from patch wings traveled much greater distances than those released from the center of the same patch. Seed shadows at edges were much smaller than those in the center. Structural heterogeneity of increased forest edges generates increased turbulence which may result in seed uplifting and longer dispersal distances. Our results also suggest that corridors could be used to facilitate dispersal between habitat patches in fragmented landscapes if they are aligned with important wind directions.
