Effect of agricultural land-use change on the structure of a temperate forest ant-plant interaction network

Studies on the responses of ant-plant interactions to land-use change have mainly focused on tropical habitats, usually without considering the impacts on the structure of interaction networks. Here we show that land-use modifies the structure of the ant-plant interaction networks in a temperate habitat. Ant-plant interactions and plant diversity were recorded in an oak forest and agricultural land in central Mexico. We registered five ant species in the oak forest, and four ant species in the agricultural land. Plant diversity was higher in the agricultural land than in the oak forest. In the ant-plant networks of both sites, our results showed a higher dependence of ants on the plants on which they feed than vice versa, and the antsFormicaspp. and the plantsBarkleyanthus salicifoliuswere the species with the most strength and greatest influence in the network structure. The ant-plant network in the oak forest showed a nested structure. However, the network at the agricultural land site showed non-nestedness; the identity of both ants and plants with the highest values of specialization was different and the number of ant species in the network was decreased, but the number of plant species with which they interacted significantly increased. Both ant-plant networks were equally tolerant to simulated extinction of individual species. We conclude that temperate forest ant-plant networks can be inherently fragile and susceptible to the effects of agricultural land-use change, not on the number of interacting species but on their identity.