Soil disturbance effects on the composition of seed-dispersing ants in roadside environments.

Abstract

Myrmecochory (the dispersal of seeds by ants) is a significant ecological process in sclerophyll woodlands, but habitat disturbance is known to alter the extent and success of this mutualism. We investigated the influence of soil disturbance on the composition of the seed-dispersing ant community. Surveys were conducted in roadside verges where soils are regularly disturbed by road maintenance activities. Using a 'cafeteria' bait station approach, we selected 24 roads of different widths to investigate ant composition and abundance in relation to soil disturbance. We found ant species richness was greater in non-disturbed than disturbed zones, where road verge width significantly influenced results. The composition and abundance of individual seed-dispersing ant species varied between disturbed and non-disturbed zones. Rhytidoponera metallica were more abundant in non-disturbed sites, whereas Melophorus bruneus and Monomorium rothseini were more frequently recorded in disturbed areas. Commonly found Iridomyrmex purpureus was significantly more abundant in disturbed zones in narrow roadsides and vice versa in wide roadsides, and strongly influenced total community composition. Variation in the abundance of commonly recorded Iridomyrmex and Monomorium genera were related more to site conditions (roadside width and habitat) than soil disturbance. The rich composition of seed dispersing ants in roadside environments, and the effects of soil disturbances on these ant communities that we describe, provide a key insight to important seed dispersal vectors occurring in fragmented rural landscapes.