Habitat fragmentation and corridors have been shown to affect abundances and distributions of species including those of the fire ant, Solenopsis invicta, and Florida harvester ant, Pogonomyrmex badius. However, such studies are typically short and understanding the long-term effects is important for assessing the impacts of fragmentation and effectiveness of corridors to mitigate those impacts. To examine this, we completed surveys of S. invicta and P. badius nests in 2007 and 2018 in a landscape-scale experiment (N=4 blocks) that manipulates connectivity and patch shape. Each block consists of a center patch surrounded by four peripheral patches, one connected by a 150-meter corridor, one winged to simulate the high edge:area ratio of the corridor, and one isolated rectangle. We recorded size and location data for each S. invicta and P. badius nest within each patch. We asked the following questions: 1. How do patch connectivity, patch shape, and within-patch-distance to the edge affect the distribution, abundance, and size of S. invicta and P. badius colonies? 2. How do these effects change over time?
Results/Conclusions
Our analyses show similar levels of increase in abundance for both species from 2007 to 2018 (71% S. invicta; 59% P. badius). In 2007, S. invicta nest size did not significantly differ across patch type or distance to the edge (p>0.05). However, in 2018, S. invicta nest size interacts with patch type and distance to the edge so that the largest nests are at the center of connected patches. We found a similar pattern for P. badius. Patch type had no effect on the density of S. invicta nests in 2007 or 2018 (p>0.05). In 2007, there was a higher density of S. invicta nests along the edge compared to the center (p=0.01). While we see no significant effects of patch type or distance to the edge on P. badius nest density in 2007, in 2018, we see a significant interaction between patch type and distance to the edge (p=0.02), driving P. badius towards the centers of winged patches. These results suggest that connectivity is affecting both S. invicta and P. badius similarly to influence nest size and location in connected patches, while edge effects may be affecting the species differently.