Spatio-temporal response patterns of ecological networks to anthropogenic stressors

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Ecological restoration is employed widely in biodiversity conservation to counteract ecosystem degradation and slow the loss of diversity. Yet the efficacy of restoration interventions for supporting self-sustaining communities has rarely been quantified. Instead of focussing only on species as the unit of study, researchers and conservationists aim to understand, preserve and restore ecosystem functioning, which is largely maintained by interactions between species. Understanding community-wide responses of biotic interactions to environmental change is needed to aid conservation management and to project ecosystem functions and services to future land-use and biodiversity scenarios. Here, I aim to advance understanding of the mechanisms that link environmental threats (e.g. invasive species) and the mitigation of these threats (e.g. through ecological restoration) to ecosystem functioning, and provide predictions on how to sustain ecosystem functions (e.g. pollination) under future scenarios of biodiversity loss. Specifically, the first of two project components will address research the longer-term spatio-temporal responses of the removal of exotic species on native mutualistic (pollination and seed dispersal) and antagonistic (nectar and pollen thieves and seed predator) interactions between species. I will experimentally evaluate the net gains and losses to native plant fitness of both interaction types and analyse their direct and indirect effects on community dynamics by implementing a multilayer network approach. The second component will investigate changes in pollinator behaviour in response to two types of community-level interventions: the removal of invasive exotic plants (restoration experiment), and the augmentation of exotic honey bees in plant-pollinator communities (augmentation experiment). I will evaluate how exotic and native super-generalist pollinators exert competition for floral resources on less abundant flower-visitors in pollination networks and contribute to pollination success of endangered plants under the two experimental scenarios. To increase the generality of our experimental approach I will model interaction dynamics of pollination networks with cost and fitness functions to account for intra- and interspecific competition between exotic and native pollinators. The predictions derived from this model will be cross-validated with pollination network data from the field experiments and earlier published work from the same system. The proposed research will provide an important contribution to advancing basic and applied ecological knowledge on the impact of environmental change on ecosystem functions, and assist with implementing science-based conservation management strategies to alleviate biodiversity loss.