Effects of defaunation on soil-plant interactions in tropical forest

Abstract

The loss of ecosystem engineers may lead to ecological changes that can affect even the lowest trophic levels. Soil mycorrhizal fungi interact with more than 80% of all plants, forming mutualistic interactions that are critical for the maintenance of the whole ecosystem. Despite substantial advances in microbial ecology, there is still a large knowledge gap about soil fungal diversity and the factors that shape communities and their interactions with other taxonomic groups, particularly in the hyper-diverse rainforests. We propose to examine how defaunation, the loss of large herbivore mammals (i.e. tapirs Tapirus terrestris and white-lipped peccary Tayassu pecari) mediates the diversity and distribution of arbuscular mycorrhizal (AM) fungal communities. To achieve our aims we will collect scats from different mammal species, soil and fine root samples for spore and DNA analyses to answer three main questions: (1) Are small and large mammals important dispersers of mycorrhizal fungal spores in the Atlantic forest? (2) Does the loss of large herbivore fauna reduce mycorrhizal associations? (3) Is defaunation linked with losses in soil carbon stocks through the reduction of AM fungal diversity and abundance? By answering these questions, we aim to expand the knowledge on a cryptic, but crucial component of forest diversity and functioning, the soil mycorrhizal fungi, also placing the below-ground dynamics in the context of the eminent defaunation of the Atlantic rainforest. (AU)