Does topography matter in the canopy? Spatial variation of ant assemblages across vertical and horizontal gradients

Both vertical stratification and topography are fundamental drivers of insect community assembly in forest ecosystems. However, how these multidimensional gradients interact remains poorly understood. We hypothesized that the influence of topography on ant communities would be less pronounced in the canopy than on the forest floor, because extreme environmental filtering in the upper strata restricts the community to a specialized set of species regardless of local topography.

Ant communities were sampled using bait traps in the canopy (8–11 m) and on the forest floor (0 m) across 26 plots representing different topographic positions and forest ages within subtropical evergreen broad‐leaved forests in Japan.

Thirty ant species were identified. α ‐diversity was significantly higher on the forest floor, peaking on floor‐level ridges, whereas β ‐diversity was higher in the canopy. Overall species composition was influenced independently by both vertical stratum and topography, with no significant interaction detected. This indicates that the effects of vertical stratification are maintained across different topographies and that significant topographic effects consistently shape ant communities across both forest strata.

Our findings demonstrate that topography and vertical stratification are primary, independent drivers of spatial heterogeneity in subtropical ant communities. By providing distinct environmental conditions across the forest profile, this multidimensional geodiversity supports diverse ant assemblages at the landscape scale. Accounting for these multidimensional environmental gradients is essential for understanding the complex mechanisms of community assembly in forest ecosystems.