Spatial ecology of peatland ecosystems: Spatial self-organization and catastrophic shifts in bogs

Abstract

Positive feedback interactions, as between plants and their abiotic environment, may have the consequence that an ecosystem has alternate stable equilibrium states. As a result, a gradual change in environmental conditions may lead to discontinuous, catastrophic shifts in such ecosystems. Until now, the occurrence of catastrophic shifts is hardly predictable. However, a recently developed idea is that self-organized vegetation patterns might serve as an indicator for imminent catastrophic shifts. Because self-organized vegetation patterns are a common feature of northern peatland bogs, we examine to what extent these causally related concepts (positive feedbacks, alternate stable states, spatial self-organization and catastrophic shifts) might contribute to a better understanding of this type of ecosystems. Empirical and theoretical studies reveal that many positive feedbacks can be present in bogs, which may generate alternate stable states. Furthermore, stratigraphic peat analysis has shown that large and abrupt transitions do occur in bogs. However, the relative contribution of each of these feedbacks to the self-organized vegetation patterns in bogs and the possible relation with catastrophic shifts remain unclear. Conclusively, a research design is discussed that addresses the current gaps in knowledge about the way positive feedbacks may lead to alternate stable states and spatial self-organization in bogs, and its possible indication of catastrophic shifts.