Environmental determinants of leaf-litter ant community composition along an elevational gradient

Ant communities are extremely diverse and provide a wide variety of
ecological functions in tropical forests. Here we investigated the abiotic
factors driving ant composition turnover across an elevational gradient at
Mont Itoupé, French Guiana. Mont Itoupé is an isolated mountain whose top
is covered by cloud forests, a biogeographical rarity that is likely to be
threatened according to climate change scenarios in the region. We
examined the influence of six soil, climatic and LiDAR-derived vegetation
structure variables on leaf-litter ant assembly (267 species) across nine
0.12-ha plots disposed at three elevations (ca. 400, 600 and 800m asl). We
tested (a) whether species co-occurring within a same plot or a same
elevation were more similar in terms of taxonomic, functional and
phylogenetic composition, than species from different plots/elevations,
and (b) which environmental variables significantly explained
compositional turnover among plots. We found that the distribution of
species and traits of ant communities along the elevational gradient was
significantly explained by a turnover of environmental conditions,
particularly in soil phosphorus and sand content, canopy height and mean
annual relative humidity of soil. Our results shed light on the role
exerted by environmental filtering in shaping ant community assembly in
tropical forests. Identifying the environmental determinants of ant
species distribution along tropical elevational gradients could help
predicting the future impacts of global warming on biodiversity
organization in vulnerable environments such as cloud forests.