Nineteen years of field data on ant communities (Hymenoptera: Formicidae): What can we learn?

For 19 consecutive years I sampled litter-ant communities in three temperate deciduous forests in the northeastern USA (West Virginia, New York, Vermont). Cumulative species richness per site ranged from 13 to 16 species but had not reached a sampling asymptote at the southern-most site (West Virginia). Nest density varied seasonally, but was consistently higher in the two northern sites (New York and Vermont). In the Vermont site, nest density declined significantly over the 19 years, probably because of ongoing forest succession; studies of ant community shifts to infer large-scale phenomena such as global climate change must separate out such background temporal variation. We detected patchiness of ant nests at three spatial scales. The smallest-scale reflected colony subdivision (polydomy) whereas medium-scale and large-scale patchiness reflected habitat heterogeneity; differences between sites indicated effects at a larger regional scale as well. There was little evidence that competition between species affected co-occurrence or nest spacing. While resource competition and behavioral interactions predominate in many ant assemblages, their effects appear to be weak in temperate litter-ant assemblages.