Data from: Elevation and leaf litter interact in determining the structure of ant communities on a tropical mountain

Tropical mountains encompass a wide range of environmental conditions and
are useful models for studying drivers of community structure.
Invertebrate species richness and abundance show various elevational
patterns. However, the drivers of these differences are not well
understood, although microhabitat complexity is potentially important. We
studied ground-dwelling ants using pitfall trapping and hand collection on
Mt. Wilhelm (Papua New Guinea) from 169 to 3,795 m a.s.l. We tested for
the effects of elevation and leaf litter depth (as a measure of
microhabitat complexity) on ant abundance, species richness and
composition. We sampled 118 species, with ants present up to 2,331 m
a.s.l. Species richness peaked at mid-elevation (~700 m), but the
elevational pattern for abundance varied depending on sampling scale. Leaf
litter depth negatively affected abundance once elevation had been
accounted for, while elevation and litter depth had an interactive effect
on species richness. Species richness was positively related to litter
depth at lower elevations, but negatively above ~700 m. Species
composition varied with elevation and less strongly with leaf litter
depth. We speculate that in the lowlands, litter depth rather than
temperature limits ant communities. At high elevations, the deeper litter
decreases temperature of the litter layer, and temperature becomes
limiting. At mid elevations, temperature is not yet too low, and litter is
still relatively deep, hence generating a mid-elevation peak in ant
richness. Our results may explain differing richness-elevation patterns of
litter arthropods around the world, and provide testable predictions for
future studies on this topic.