Ecological boundaries in the context of hierarchy theory

Ecological boundaries have been described as being multiscalar or hierarchical entities. However, the concept of the ecological boundary has not been explicitly examined in the context of hierarchy theory. We explore how ecological boundaries might be envisioned as constituents of scalar hierarchical systems. Boundaries may be represented by the surfaces of constituents or as constituents themselves. Where surfaces would correspond to abrupt transition zones, boundary systems might be quite varied depending on hierarchical context. We conclude that hierarchy theory is compatible with a functional vision of ecological boundaries where functions can be largely represented as the processing or filtering of ecological signals. Furthermore, we postulate that emergent ecological boundaries that arise on a new hierarchical level may contribute to the overconnectedness of mature ecosystems. Nevertheless, a thermodynamic approach to the emergence and development of boundary systems does indicate that in many situations, ecological boundaries would persist in time by contributing to the energy production of higher hierarchical levels. (c) 2008 Elsevier Ireland Ltd. All rights reserved.