Is an ecosystem perspective sufficient to understand meta‐ecosystem processes? A critical reflection

Meta‐ecosystems are the largest and probably most complex structures investigated in ecology. Because of their complexity they are often separated into their respective sub‐systems and then studied in isolation. This is often done without analysing whether an understanding of the individual ecosystems can lead to a proper understanding of the meta‐ecosystem, likely because we lack clear guidelines as to when such a separation is sufficient. Here, we propose four conceptual models for which a separation may approximate the full dynamics. For each of these models we provide empirical evidence from riparian meta‐ecosystems to showcase that the terrestrial or aquatic ecosystem should likely not be studied in isolation. Finally, we provide a theoretical framework to assess how strongly two ecosystems are linked and test this new method on virtual data. We show that the new method is a good approximation of the coupling strength between two ecosystems. Finally, we discuss how this framework might be applied in future empirical research.