We investigated ant species richness, interspecific behavioral interactions, and community composition in adjacent forested and open habitat plots in two forest types of the northeastern United States: 1) the more common hemlock-White Pine forest studied at Harvard Forest Long Term Ecological Research Station in central Massachusetts, and T) the rare Pitch Pine barrens of Myles Standish State Forest in southeastern Massachusetts, which also provide habitat for multiple rare and endangered species. Overall, we found that species richness, behavioral interactions, and ecological traits vary between forested and adjacent open habitat plots. The number of species is five times higher per plot in the hemlock-White Pine open habitat (compared to forest habitat), but this pattern (i.e., higher species richness in open vs. forested plots) is not observed in the Pitch Pine barren site. Non-metric multidimensional scaling analyses suggest that community composition is significantly different between forest and open plots at both sites. However, community composition in open plots at both sites did not significantly differ from each other. We show that behaviorally dominant and submissive species mostly occur in open plots while neutrally interacting species are more restricted to forested plots, suggesting that interspecific competitive dynamics may be contributing to the community assembly patterns observed in open habitats. Our findings suggest that conservation and management for both open and forested habitat at either site is extremely important when attempting to maintain optimal ant biodiversity because each habitat type provides suitable conditions for different suites of ant communities.