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Restoration of Ailing Wetlands

Figure 1

Different potential ways that ecosystem state may change in relation to the level of environmental disturbance.

Solid lines denote pathways of state changes from natural to degraded conditions, and the dashed line indicates a transition where the system jumps from a natural to a degraded state. The figure illustrates three general scenarios. Ecosystems may undergo gradual degradation with a rise in disturbance level and may recovery gradually as the disturbance is abated. Ecosystems may exhibit threshold-like behavior in which a certain level of disturbance causes an abrupt change in state and disturbance abatement causes an abrupt “up-hill” return in ecosystem state. Finally, an ecosystem may exhibit a threshold shift in ecosystem state that may only be recoverable with a large turnaround of the critical environmental parameter or disturbance that caused the system to shift from the original state. The scientific challenges in restoration ecology are: characterizing what a natural “green” state is; identifying how long a perturbation must be in place to determine whether the system changes gradually or abruptly; and how long it will take to reverse the effects of a disturbance. Figure is adapted from [10].

Figure 1

doi: https://doi.org/10.1371/journal.pbio.1001248.g001