Effects of fire management and grazing by cattle on ant communities in south-east Queensland open forests

Abstract

Forest management practices, such as prescribed burning and cattle grazing, have come under increasing scrutiny due to their potential to cause damage to local ecosystems. This study examined the impacts of these practices on ant communities at Bauple State Forest in south-east Queensland. Ant community structure was studied at three locations subjected to different long-term burning frequencies (fire protected, low intensity spring burns at 2–3 year intervals and annual low intensity spring burns). Within the annually burned area, the effects of fire and grazing exclusion for a three-year period were also examined. The results indicate that fire frequency has a significant impact on ant community structure, most probably through its influence on the structural environment (alterations to insolation and ground cover). Ant abundance, species richness and the relative abundance of Dominant Dolichoderines were significantly lower in areas of lower fire frequency, while the relative abundance of Opportunists increased. Ant community data at the two burned areas were significantly different from the long-term unburned area, suggesting regular fire events have a considerable impact on ant community structure. After three years of experimental fire exclusion, both the environmental and ant community structure resembled the long-term infrequently burned site, suggesting a rapid response by the ant community to changes in vegetation structure and the related abiotic characteristics. A significant reduction in ant abundance and species richness was observed by the third year and a trend to reduced abundance of Dominant Dolichoderines and increased Opportunists was observed in fire-protected plots. Experimental release from grazing pressure for a period of 36 months did not result in any significant differences in ant community, possibly indicating that grazing impacts were not readily reversible in the short term.