A common management tool that mitigates the effects of fragmentation is to connect isolated pieces of habitat with corridors. Corridors have been shown to increase plant species richness, an effect dependent on dispersal mode when considering plant species dispersed by wind, birds, and gravity. Poorly understood is how corridors affect myrmecochory (seed dispersal by ants). Landscape features, such as corridors, could affect ant-mediated seed dispersal by altering the context (e.g. connectivity, distance to an edge, temperature, etc.) in which ants are active. We conducted this study within a landscape-scale experiment with large blocks consisting of a center habitat patch surrounded by four peripheral patches, one connected by a 150-meter long corridor (N=4 blocks). In each peripheral patch, we placed eight depots containing seeds with elaiosomes (structure found on seeds indicating dispersed by ants) at two distances from the patch edge. During observations of the seed depots, we collected specimens of ants that removed seeds, later identifying specimens to species. Here we ask, (1) What are the relative effects of corridors, distance from edge, and ant species identity on the rate of seed dispersal?, and (2) Do these variables interact to affect the rate of seed dispersal?
Results/Conclusions
We identified 16 ant species that removed seeds from our depots. The most common species were Solenopsis invicta (visited ~42% of depots), Crematogaster lineolata (visited ~20% of depots), and Forelius pruinosus (visited ~9% of depots). We did not detect an effect of connectivity, distance from edge, or an interaction between these two variables on the rate at which seeds were removed (measured as seeds removed per minute) from our depots (p>0.05). However, we did detect an effect of ant species identity on the rate of seed removal (p = 0.03) with S. invicta, an invasive, non-native ant species in our system, removing seeds from more seed depots than F. pruinosus (p = 0.005) and marginally more seed depots than C. lineolata (p = 0.09), both native ant species in our system. Taken together, these results indicate that S. invicta may play an important role in the dispersal of ant-dispersed plants in our system. Further studies are needed to determine the consequences of this on seed fate (e.g. dispersal distance, viability of dispersed seeds).