Community structure in north temperate ants: temporal and spatial variation

Abstract

Ant communities in Vermont and New York woods were sampled in four time periods to determine species composition, relative abundances, and nest locations in space. The Vermont community was richer, containing more species and higher nest densities than New York. Both communities followed the geometric distribution of species abundances, suggesting that a single resource was mediating competition. The resource most clearly implicated was suitable nest sites, principally pre-formed plant cavities. Nonrandom species associations, underdispersion in every season, and the occurrence of incipient nests overwintering aboveground all implicated shortage of such cavities. Furthermore, microhabitat differences which produce suitable nest sites occur over a very small scale in these communities.

The cavity-nest ant Temnothorax crassispinus prefers larger nests

“…data). Considering that the colonies containing *150 workers could not fit into 470 mm 3 nests during the laboratory experiment, and that Temnothorax ants are subject to intense competition for nest sites (Herbers, 1989;Herbers and Banschbach, 1995;Foitzik and Heinze, 1998), the choice of a bigger nest may ensue from the perspective of colony growth in the season, since the ants of this species make only minor modifications to the nest sites they find.…”

“…For this reason, colonies may be forced to move nest locations frequently, up to several times per season, due to the destruction of their previous nest (e.g. when a nest is accidentally crushed or no longer inhabitable as a result of decaying processes) (Herbers, 1989;Herbers and Johnson, 2007).…”

Cost to the cavity-nest ant Temnothorax crassispinus (Hymenoptera: Formicidae) of overwintering aboveground

“…Ants are typically highly abundant in almost all terrestrial ecosystems (Wilson & Hölldobler, 2005). Probably most species of ants inhabiting the temperate zone overwinter underground, but cavity-nesting ants of the genus Temnothorax remain aboveground throughout the winter (Herbers, 1989), during which time they could be exposed to extremely cold conditions. Such exposure should lower their survival, so overwintering aboveground (compared to overwintering in the soil) should provide benefits that outweigh the mortality costs associated with such behaviour.…”

“…The colonies are usually monogynous (i.e., have one queen) (Heinze & Buschinger, 1988;Seifert, 2007), although separate colonies may integrate before winter (Seifert, 2007). The life history aspect that may account for the puzzling overwintering behaviour of Temnothorax ants could be strong competition for nest sites (Herbers, 1989;Herbers & Banschbach, 1995;Foitzik & Heinze, 1998;DeHeer & Herbers, 2004). It is possible they overwinter on the surface because it is advantageous to occupy and remain in good nest sites because they are in limited supply (Herbers, 1989;Herbers & Johnson, 2007).…”

“…The life history aspect that may account for the puzzling overwintering behaviour of Temnothorax ants could be strong competition for nest sites (Herbers, 1989;Herbers & Banschbach, 1995;Foitzik & Heinze, 1998;DeHeer & Herbers, 2004). It is possible they overwinter on the surface because it is advantageous to occupy and remain in good nest sites because they are in limited supply (Herbers, 1989;Herbers & Johnson, 2007). I hypothesize that the ants stay aboveground rather than move underground during the winter, because the costs of exposure to cold temperatures are lower than the benefits of being in a good nest site the following spring.…”