The architecture of Multifunctional Ecological Networks

This study proposes a novel approach to assess the functional importance of species in an ecosystem by considering their multiple ecological roles, i.e. their multifunctionality. We introduce the concept of function keystonness, which focuses on the robustness of ecosystems against perturbations of ecological functions. The study is based on direct observations recently collected in the islet Na Redona of 16 plant species and 675 animal/fungus species, encompassing 1537 weighted interactions across 6 ecological functions, including pollination, herbivory, seed dispersion, and pathogen-, saprotrophic-, and symbiotic-fungal interaction. We formalize the complete relational dataset as a Resource-Consumer-Function tensor, which is interpreted as a weighted, multipartite, multilayer network. By integrating out the consumer index, we construct a Multifunctional Ecological Network, which shows a stylized nested structure suggesting that certain ecological functions and plant species can be classified as generalists or specialists. By projecting such into the function and plant class, we quantify the ecosystem robustness against perturbations of plant species and ecological functions. The framework highlights the importance of preserving weak ties to maintain ecosystem assembly and its multifunctionality, and overall offers a dual insight from the species and functional perspectives that can guide conservation efforts aimed at reducing biodiversity loss.