Conservation of an Ant-plant Mutualism in Native Forests and Ecologically-managed Tree Monocultures

The Brazilian Atlantic Forest has been replaced by homogeneous tree monocultures with potentially drastic effect on ecological interactions. We expect that ecologically-managed tree monocultures, however, can help to mitigate this impact. Here, we carried out an experiment with Inga vera (Fabaceae), an extrafloral nectary bearing plant, to test if the efficiency of ants as anti-herbivory defense is affected by the replacement of its natural habitat (Araucaria Forest) by ecologically-managed tree monocultures (plantations of Araucaria, Pinus, and Eucalyptus). Seedlings of Inga vera were transplanted to three patches of each habitat and ants were excluded from half of the plants. The abundance of ants and herbivores was low, similar among habitats, and exhibited temporal asynchrony. Number of herbivores and accumulated herbivory levels were lower in plant with ants. Rates of herbivory were extremely low and lower for young leaves than for mature leaves. The presence of ants did not affect plant performance traits measured by their growth in height, and their final numbers of leaves and leaflets. Contrary to what might be expected, ant-protected plants produced fewer leaves and leaflets than unprotected ones. In conclusion, Inga vera-ant interaction was similar between its natural habitat and the tree monocultures, indicating that potentially both species diversity and ecological processes can be conserved in ecologically-managed tree monocultures.