Effects of fire on the structure of ant–plant ecological networks with extrafloral nectaries in the Cerrado

Abstract Plants are essential components of ecosystems and depend on various interactions with animals, among which mutualistic associations with ants stand out. Defensive mutualisms mediated by extrafloral nectaries (EFNs) create complex networks that shape species coexistence and contribute to ecological stability. Understanding how these networks respond to environmental disturbances is essential for predicting ecosystem dynamics. We investigated how fire influences the structure of ecological networks between ants and plants with EFNs in an area of the Cerrado affected first by frost and then by a high-intensity forest fire. Over the course of a year, we monitored ant richness and abundance, along with ant–plant interaction patterns involving regenerating plants. We observed that fire initially promoted more widespread networks, driven by an increase in resources and the synchronized growth of plant species. The ant species Camponotus crassus emerged as a central element of the network, playing a key role in the organization and stability of the network. However, tree fauna was more sensitive to disturbance, showing a marked decline in ant species dependent on branches and trunks. In summary, fires and frosts temporarily reshape ant–plant interactions, requiring adequate long-term monitoring.