Robustness of the pollination-herbivory system with high-order interactions to habitat loss

Despite the prevalence of high-order interactions (HOIs) in pollination-herbivory metacommunities, few studies have yet explored the dynamical implications of such high-order interacting effects on the metacommunity persistence in a spatial context. Here we develop a spatially implicit patch-dynamic framework for a simple three-species system (with one pollinator and one herbivore sharing one plant species), in order to check whether and how the HOIs induced by the herbivore modify system robustness to habitat loss. We find that high-order interacting effects are a complex function of demographic characteristics, habitat loss and top-down control. Interestingly, HOIs do not affect species extinction thresholds, though they can mediate species abundances depending on habitat loss and top-down control. Furthermore, habitat loss initiates a bottom-up cascade of species extinction regardless of HOIs. The herbivore shows most susceptible to habitat loss, while both mutualists suffer the abrupt extinction at the same threshold because of their interdependence. Finally we observe that both mutualists surprisingly display diverse (including negative, positive or neutral) responses to an increase in feeding pressure, but the herbivore shows a monotonic decline in population abundance. Overall, we provide an important theoretical framework to explore the effect of HOIs on metacommunity robustness of the pollination-herbivory interactions to habitat loss at a regional scale.