The Robustness and Restoration of a Network of Ecological Networks

Networks of Networks Quantitative networks, such as those represented by food webs, have become an important way of investigating the structure of ecological communities, but thus far only encompass a small subset of species. Pocock et al. (p. 973) have linked seven different types of ecological networks to form a network of networks. They found that although networks varied in their robustness to species loss, they did not strongly co-vary; that is, what happens to one network is unrelated to what happens to another. The networks studied were identified from an agroecosystem in the southwestern UK, a habitat in which biodiversity has suffered substantially. This study succeeded in revealing which species are potential targets for restoration of ecological function in this and other systems. Analysis of seven interconnected networks on a farm reveals that they vary in their fragility, but that they do not covary. Understanding species’ interactions and the robustness of interaction networks to species loss is essential to understand the effects of species’ declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity.