Corridors help mitigate the effects of habitat fragmentation by connecting isolated habitat patches and have been shown to increase plant species richness. This effect depends on dispersal mode for wind-, bird-, and gravity-dispersed species, but relatively unknown is how corridors affect seed dispersal by ants. Corridors alter landscape structure by both the addition of edgy habitat and increasing connectivity, affecting the context in which ants are active. We did this study within a landscape-scale fragmentation experiment with blocks consisting of a center habitat patch surrounded by four peripheral patches equal in area, one connected by a 150-meter long corridor (N=4 blocks). Isolated peripheral patches are winged- or rectangular-shaped to control for the edge added with a corridor. We observed depots containing seeds dispersed by ants at two distances from the patch edge for up to an hour recording the time ants discovered seeds, when ants removed seeds, and how far seeds were dispersed. Here we ask, (1) What are the effects of corridors, patch shape, and distance from edge on the rate of seed dispersal by ants and the distance ants disperse seeds, and (2) Do connectivity, patch shape, and distance to an edge interact to affect these responses?
Results/Conclusions
We observed ants removing seeds from 79% of our seed depots, with all seeds removed within an hour from 16% of the depots. We did not find an effect of connectivity, patch shape, edge proximity, or their interactions on the amount of time it takes for ants to detect seeds nor the proportion of seeds dispersed from seed depots. However, we did find an effect of the interaction between proximity to edge and patch shape on the distance that ants dispersed seeds such that ants moved seeds almost five times further in the center of patches connected with corridors than in the center of winged patches. Additionally, we found that ants dispersed seeds over two times further at depots located at the edge than the centers of both rectangular and winged patches. We did not detect an effect of edge proximity on seed dispersal distance in patches connected by a corridor. Taken together, these results suggest that connectivity may have effects on seed dispersal by ants that are mediated through edge effects.