Aim: Terrestrial animal communities are largely shaped by vegetation and climate. With climate also shaping vegetation, can we attribute animal patterns solely to climate? To understand this, we compare the relative and interactive effects of climate and vegetation on an animal community. Our study observes ant community changes along climatic gradients (i.e. elevational gradients) within different habitat types (i.e. open and forest). We compare the explanatory powers and effect sizes of climate and vegetation variables on ant communities and describe what drives elevational distributions of ant species.

Location: Colorado Plateau, southwestern United States

Taxon: Formicidae

Methods: We sampled ants and vegetation along two elevational gradients spanning 1132m with average annual temperature and precipitation differences of 5.7C° and 645 mm, respectively. Regression analysis and structural equation modeling was then used to test the relative effects of climate and vegetation variables on ant communities.

Results: Climate variables had the strongest correlations and the largest effect sizes on ant communities, while vegetation composition, richness, and primary productivity were relatively small. Precipitation was the strongest predictor for most ant community metrics. Ant richness and abundance had a negative relationship with precipitation in forested habitats, and positive in open habitats.

Main conclusions: Our results show strong direct climate effects on ants with little or no effects of vegetation composition or primary productivity, but contrasting patterns between vegetation type (i.e. forested vs open) with precipitation. This indicates vegetation structure can modulate climate responses of ant communities. Our study demonstrates climate-animal relationships may vary among vegetation types which can impact both findings from elevational studies and how communities will react to changes in climate.

Ants through pit fall traps, vegetation through point intercept in 1m2 plots