Leaf-cutting ants in Patagonia: how human disturbances affect their role as ecosystem engineers on soil fertility, plant fitness and trophic cascades

A. G. FARJI-BRENER; M. TADEY; LESCANO, N.

Ant-Plant Interactions: Impacts of Humans on Terrestrial Ecosystems

Cambridge Universtiy Press

Lugar: United Kingdom ; Año: 2017;

InPatagonia, leaf-cutting ants play a relevant role affecting plant  fitness of several species through direct andindirect effects and enhancing soils fertility by the accumulation of theirnutrient-rich organic waste.Anthropogenic disturbances modify/interfere with thenatural role of leaf-cutting ants through several mechanisms. For example, the expansionand maintenance of roads may increase ant nests  density in areas with high occurrence ofexotic plant species, plants that in turn benefit  from the nutrient-rich ant organic wasteenhancing their fitness. This indirect, positive effect of ant nest on exoticvegetation may influence the trophic relationships between plants, aphids,aphid-tending ants and parasitoids.  However,the presence of exotic livestock may decrease leaf-cutting ant diet, affectingtheir role as primary consumers and soil modifiers: ant colonies in paddockswith high stocking rates consume less plant species and produce organic waste oflow-nutrient content. These human-induced changes in the role of leaf-cuttingants may accelerate the invasion of exotic species and diminish their importanceas soil fertilizers in natural protected areas of Patagonia.