Why are there more arboreal ant species in primary than in secondary tropical forests?

Abstract

Summary1. Species diversity of arboreal arthropods tends to increase during rainforest succession so that primary forest communities comprise more species than those from secondary vegetation, but it is not well understood why. Primary forests differ from secondary forests in a wide array of factors whose relative impacts on arthropod diversity have not yet been quantified. 2. We assessed the effects of succession-related determinants on a keystone ecological group, arboreal ants, by conducting a complete census of 1332 ant nests from all trees with diameter at breast height ‡ 5 cm occurring within two (unreplicated) 0AE32-ha plots, one in primary and one in secondary lowland forest in New Guinea. Specifically, we used a novel rarefaction-based approach to match number, size distribution and taxonomic structure of trees in primary forest communities to those in secondary forest and compared the resulting numbers of ant species. 3. In total, we recorded 80 nesting ant species from 389 trees in primary forest but only 42 species from 295 trees in secondary forest. The two habitats did not differ in the mean number of ant species per tree or in the relationship between ant diversity and tree size. However, the between-tree similarity of ant communities was higher in secondary forest than in primary forest, as was the between-tree nest site similarity, suggesting that secondary trees were more uniform in providing nesting microhabitats. 4. Using our rarefaction method, the difference in ant species richness between two forest types was partitioned according to the effects of higher tree density (22AE6%), larger tree size (15AE5%) and higher taxonomic diversity of trees (14AE3%) in primary than in secondary forest. The remaining difference (47AE6%) was because of higher beta diversity of ant communities between primary forest trees. In contrast, difference in nest density was explained solely by difference in tree density. 5. Our study shows that reduction in plant taxonomic diversity in secondary forests is not the main driver of the reduction in canopy ant species richness. We suggest that the majority of arboreal species losses in secondary tropical forests are attributable to simpler vegetation structure, combined with lower turnover of nesting microhabitats between trees.

Functional structure of ant and termite assemblages in old growth forest, logged forest and oil palm plantation in Malaysian Borneo

“…Logged forests may offer intermediate conditions that favour greater ant abundance, in which nest sites are available, but surfaces are not too complex to limit foraging, with temperatures slightly higher on average than in old growth forest. However, more highly disturbed forests, such as secondary regrowth following clearance, support fewer species due to differences in tree density, diversity and size distribution (Klimes et al 2012). In contrast, termites were more common in old growth forest than in the other two habitats.…”

Senescent stem-galls in trees of Eremanthus erythropappus as a resource for arboreal ants

“…They suggested that in populations of plants with aggregate distribution, the cavities of the plants may function as an ephemeral resource in large areas whose sites for nesting are scarce. Klimes et al (2012) report that, taken generally, primary forests tend to contain roughly twice the number of ant species as do secondary forests, most likely due to the density of plants and structural complexity of their vegetation. This aspect of primary forests makes them an ideal environment for ant colonies, presenting as they do a variety of possible locations for nesting.…”

Identification of microsatellite markers for a worldwide distributed, highly invasive ant species Tapinoma melanocephalum (Hymenoptera: Formicidae)

“…This leads to plant damage and to an increase of plant pathogens, including viral and fungal infections (Venkataramaiah & Rehman, 1989). In Papua New Guinea, T. melanocephalum was one of the only ant species whose number increased greatly in the canopy and understory of primary and secondary forests following a focused eradication of ant assemblages (Klimes et al, 2012).…”