Ecosystem engineering and predation: the multi-trophic impact of two ant species

Abstract

1. Ants are ubiquitous ecosystem engineers and generalist predators and are able to affect ecological communities via both pathways. They are likely to influence any other terrestrial arthropod group either directly or indirectly caused by their high abundance and territoriality. 2. We studied the impact of two ant species common in Central Europe, Myrmica rubra and Lasius niger, on an arthropod community. Colony presence and density of these two ant species were manipulated in a field experiment from the start of ant activity in spring to late summer. 3. The experiment revealed a positive influence of the presence of one ant colony on densities of decomposers, herbivores and parasitoids. However, in the case of herbivores and parasitoids, this effect was reversed in the presence of two colonies. 4. Generally, effects of the two ant species were similar with the exception of their effect on Braconidae parasitoid densities that responded positively to one colony of M. rubra but not of L. niger. 5. Spider density was not affected by ant colony manipulation, but species richness of spiders responded positively to ant presence. This effect was independent of ant colony density, but where two colonies were present, spider richness was significantly greater in plots with two M. rubra colonies than in plots with one colony of each ant species. 6. To test whether the positive ecosystem engineering effects were purely caused by modified properties of the soil, we added in an additional experiment (i) the soil from ant nests (without ants) or (ii) unmodified soil or (iii) ant nests (including ants) to experimental plots. Ant nest soil on its own did not have a significant impact on densities of decomposers, herbivores or predators, which were significantly, and positively, affected by the addition of an intact nest. 7. The results suggest an important role of both ant species in the grassland food web, strongly affecting the densities of decomposers, herbivores and higher trophic levels. We discuss how the relative impact via bottom-up and top-down effects of ants depends on nest density, with a relatively greater top-down predatory impact at higher densities.

Diversidade e riqueza de formigas (Hymenoptera: Formicidae) em remanescentes de Mata Atlântica na Bacia Hidrográfica do Alto Tietê, SP

“…Ao atuarem como engenheiras (Folgarait 1998, Sanders & Van Veen 2011, as formigas alteram as propriedades estruturais e químicas do solo por meio da construção de galerias, aumentando a porosidade, drenagem, aeração, volume e incorporação da matéria orgânica (Hole 1981, Lavelle et al 1997, Risch & Jurgensen 2008, Sanders & Van Veen 2011. Essas mudanças influenciam positivamente a taxa de decomposição e produtividade do sistema (Sanders & Van Veen 2011).…”

The mixed effects of experimental ant removal on seedling distribution, belowground invertebrates, and soil nutrients

“…Ants are ubiquitous in most ecosystems, and are often described as ecosystem engineers (Jones et al 1994, Folgarait et al 2002, Sanders and Frank van Veen 2011 and keystone species (Gove et al 2007). Indeed, there is some evidence that ants play key roles in shaping plant population dynamics (Kalisz et al 1999, Rodriguez-Cabal et al 2009), altering arthropod community structure both above and belowground (Wimp and Whitham 2001, Moya-Laraño and Wise 2007, Wardle et al 2011, Sanders and Frank van Veen 2011, or modulating ecosystem processes (Folgarait 1998).…”

“…Ants prey upon soil-and litter-dwelling invertebrates, and, at least in come cases, affect the abundance of particular soil taxa and the composition of soil communities (Wagner et al 1997, Laakso 1999, Laakso and Setala 2000, Lenoir et al 2003, Wilson 2005, MoyaLorano and Wise 2007, Wardle et al 2011, Sanders and Frank van Veen 2011. Ants may indirectly influence soil nutrients by suppressing populations of microbe-feeding mites and Collembolans.…”

“…Indeed, there is some evidence that ants play key roles in shaping plant population dynamics (Kalisz et al 1999, Rodriguez-Cabal et al 2009), altering arthropod community structure both above and belowground (Wimp and Whitham 2001, Moya-Laraño and Wise 2007, Wardle et al 2011, Sanders and Frank van Veen 2011, or modulating ecosystem processes (Folgarait 1998). However, surprisingly few studies have experimentally removed ants from an intact understory community to assess simultaneously their long-term impacts on plant population structure, the structure of belowground arthropod communities, and soil nutrient dynamics (but see Wardle et al 2011).…”

Influência do desenvolvimento florestal sobre a comunidade edáfico-epígea de Arthropoda e a mirmecofauna: bases para a bioindicação do processo sucessional na restauração ecológica

“…Assim, a quantidade e complexidade das interações entre as formigas e outros elementos do ecossistema indicam que a mirmecofauna tanto participa ativamente da caracterização dos ecossistemas, como também são sensíveis às mudanças do meio físico e na comunidade (Andersen, 2000;Kaspari, 2000;Crain & Bertness, 2006;Hastings et al;Steiner et al, 2010, Sanders & van Veen, 2011 e, por esse motivos, as formigas tem sido consideradas bioindicadores ecológicos (Ribbas et al, 2012).…”