Road preference of ants in a Japanese warm temperate forest and its implications for the regeneration of myrmecochorous sedges

In warm temperate forests where light availability is generally low, roadsides often provide a refuge for myrmecochores. Therefore, whether or not ants disperse seeds along the roadsides should critically affect the regeneration of myrmecochores. Nonetheless, the dispersal behaviors of ants along roadsides have rarely been investigated in warm temperate forests. This study examined the road preference of two seed dispersing ants in warm temperate Japan, Formica japonica and Pheidole nodus. We located ant nests using baits placed at the vicinity of myrmecochorous sedges and examined the road preferences of ants and their consequences for seed dispersal by comparing the observed road proximity of ant nests with the simulated value assuming a random dispersal direction. Nests of both ant species were significantly closer to the road than in those simulated assuming random dispersal, which confirmed their road preferences. The road preference of F. japonica reduced the risk of seed loss into the forest interior to one-ninth of the random dispersal. This trend was not observed in P. nodus due to its short dispersal distance relative to roadside width. Although light availability was higher around nests of P. nodus due to their closer proximity to the road than nests of F. japonica, adult sedges were located farther from the road than the nests of P. nodus. This implies that nests of P. nodus are unsuitable microhabitats for sedges. These results suggest that ants can disperse seeds along forest roadsides in warm temperate forests, but the efficiency vary among ant species.

Automated summary

This study found that ants can disperse seeds along forest roadsides in warm temperate forests, with different ant species showing varying efficiency and preferences. The dispersal of seeds by ants has significant implications for seed regeneration in these forests.