Disentangling the Diversity of Arboreal Ant Communities in Tropical Forest Trees

Abstract

Tropical canopies are known for their high abundance and diversity of ants. However, the factors which enable coexistence of so many species in trees, and in particular, the role of foragers in determining local diversity, are not well understood. We censused nesting and foraging arboreal ant communities in two 0.32 ha plots of primary and secondary lowland rainforest in New Guinea and explored their species diversity and composition. Null models were used to test if the records of species foraging (but not nesting) in a tree were dependent on the spatial distribution of nests in surrounding trees. In total, 102 ant species from 389 trees occurred in the primary plot compared with only 50 species from 295 trees in the secondary forest plot. However, there was only a small difference in mean ant richness per tree between primary and secondary forest (3.8 and 3.3 sp. respectively) and considerably lower richness per tree was found only when nests were considered (1.5 sp. in both forests). About half of foraging individuals collected in a tree belonged to species which were not nesting in that tree. Null models showed that the ants foraging but not nesting in a tree are more likely to nest in nearby trees than would be expected at random. The effects of both forest stage and tree size traits were similar regardless of whether only foragers, only nests, or both datasets combined were considered. However, relative abundance distributions of species differed between foraging and nesting communities. The primary forest plot was dominated by native ant species, whereas invasive species were common in secondary forest. This study demonstrates the high contribution of foragers to arboreal ant diversity, indicating an important role of connectivity between trees, and also highlights the importance of primary vegetation for the conservation of native ant communities.

Ant assemblages (Hymenoptera: Formicidae) associated to environments of a rural property in the extreme western region of the state of Santa Catarina

“…The rarefaction curves showed no saturation, indicating that the sampling effort did not survey the ant assemblages fully, being thus possible to register additional ant species in all environments. Nevertheless, the lack of stabilization in the sampling curves is commonly observed for ant communities, a pattern that may be related to the aggregate distribution or rarity of some species (KLIMES et al, 2015).…”

Secondary succession has surprisingly low impact on arboreal ant communities in tropical montane rainforest

“…Trees in each plot were gradually felled, starting in one plot corner and advancing systematically through the plot. Although trees suffer some damage when felled, it introduces only minimal bias to ant sampling, as loss of colonies and influx of foragers from the ground after felling are rare (Klimes et al 2015). The felling took approximately 3 months per plot with a team of 15 local workers and one supervising researcher.…”

“…previously sampled (Klimes et al 2015, Klimes 2017. We used data from the montane forest studied here and data from the same two forest stages in Wanang lowland forest (~100 m.a.s.l.)…”

“…This effect can be propagated along trophic cascades to predators and scavengers (Bowman et al 1990, Basset et al 2012. For instance, old-growth vegetation offers a higher epiphytic load and microhabitat variability, and feeding and nesting resources are more stratified and diverse compared to early-successional stages (Schulze et al 2004, Yanoviak et al 2007, Klimes et al 2015, del Pliego et al 2016. For instance, old-growth vegetation offers a higher epiphytic load and microhabitat variability, and feeding and nesting resources are more stratified and diverse compared to early-successional stages (Schulze et al 2004, Yanoviak et al 2007, Klimes et al 2015, del Pliego et al 2016.…”

“…Current knowledge of arboreal ant communities at high elevations is limited to a single study of a few individual high-canopy trees in Costa Rica (Schonberg et al 2004). In lowland rainforest, a plot-based study also found significant increases in ant diversity (including their nests), and high species turnover throughout succession driven by changes in tree density, tree size, and microhabitat diversity (Klimes et al , 2015. Hence, no data for ant nests from montane forest tree canopies are available.…”