A system is proposed whereby ant functional groups are used as structural attributes to classify ninety-four Australian ant communities in a manner analogous to the classification of vegetation according to predominant life-forms. In terms of their responses to stress and disturbance, Dominant Dolichoderinae (DD) are considered analogous to trees, functionally subdominant Generalized Myrmicinae (GM) to shrubs and ruderal Opportunists (OPP) to grasses. Community types DDO (twenty-two sites), DD1 (twenty-two sites), DD2 (eight sites), DD3 (thirty-nine sites) and DD4 (three sites), respectively, are defined as having the relative abundance of Dominant Dolichoderinae <10%, 10-19%, 20-29%, 30-70% and >90%. They are structurally analogous to treeless plant communities, open woodlands, woodlands, forests and plantations, respectively. DDO communities are classified as DD0GM (analogous to shrublands) when Generalized Myrmicinae predominate, DD0OPP (analogous to grasslands) when Opportunists predominate and DD0CS (analogous to cold-adapted heathlands) when neither functional group is abundant. Similarly, the relative abundances of Generalized Myrmicinae and Opportunists are used to classify DD1-3 communities in a manner analogous to the classification of woodlands and open forests according to understorey type. DD3OPP communities, for example, where the relative abundance of Dominant Dolichoderinae is 30-70% and Opportunists are predominant among remaining ants, are structurally analogous to grassy forests. The distribution of ant functional groups is considered in relation to stress and disturbance by adopting Grime's (1979) triangular ordination concepts and nomenclature, with ant community structural types being analysed in terms of the relative importance of competition, stress and disturbance as factors regulating community structure. DD0 and DD1 structural types are stress-tolerant, or ruderal, communities; DD2 and DD3 types are competitive communities when Generalized Myrmicinae are abundant, and competitive ruderal or competitive stress-tolerant ruderal when Opportunists are predominant among non-dolichoderines; and DD4 communities are competitive ruderal. In temperate regions, seasonal changes in ant community structure parallel those occurring along biogeographical gradients spanning comparable temperature regimes. A positive relationship was found between the abundance of functionally dominant ants (DD + GM) and species richness. Plant and ant communities often differ from each other in their responses to the same stress or disturbance, such that there is often a poor correspondence between ant and plant community structural type at any particular site.
