Arboreal Ant Community of a Pine Forest in Northern Florida

Abstract

The arboreal ant fauna of the longleaf and slash pine forests of the Apalachicola National Forest in northern Florida was studied using baits placed on trunks 1 m above ground level. Crematogaster ashmeadi Mayr was by far the most abundant ant attracted to the baits, occurring on ~50% of all the trees. In addition to C. ashmeadi, another 10 species of ants, both ground-nesting and arboreal-nesting, were commonly captured. There was a strong relationship between the identity and abundance of species of ants on pines and the mean tree diameter, indicating that the ant fauna changed as trees grew. In young, recently regenerated stands, baits attracted mostly ground-nesting species of ants. Newly mated C. ashmeadi queens colonize the dead branches of pine saplings. As tree size increased, tree occupancy by C. ashmeadi rose to a maximum of 60% in middle-sized trees and fell to 50% in the largest trees. Parallel to these changes, the proportion of trees occupied by ground-nesting ants fell from 33% in the smallest pines to ~15% in the largest, whereas those occupied by arboreal ants other than C. ashmeadi rose from 2 to 25%. The data suggested that C. ashmeadi is a dominant ant species with which other species do not easily coexist. Coexistence of arboreal ants increased with tree size such that the proportion of trees with >1 species increased steadily from ~4% in the smallest pines to ~19% in the largest. The total number of species was about the same in small, medium, and large trees, but the identity of these species changed. As in other ant communities, the assembly of the arboreal ant community in this pine forest is probably an example of the nested-subset phenomenon. That is, the occurrence of species is determined by their ability to coexist with the dominant, aggressive, large-colonied species, in this case, C. ashmeadi.