n. The process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed.
Ecological restoration is an activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity, and sustainability. Frequently, the ecosystem that requires restoration has been degraded, damaged, transformed, or entirely destroyed as the direct or indirect result of human activities. In some cases, these impacts to ecosystems have been caused or aggravated by natural agencies, such as fires, floods, storms, or volcanic eruption, to the point at which the ecosystem cannot recover its previous state or its historical developmental trajectory.
Because restoration attempts to return an ecosystem to its historical trajectory, historical conditions are the starting point for restoration design. The restored ecosystem will not necessarily recover its former state since contemporary constraints and conditions may cause it to develop along an altered trajectory. The historical trajectory of a severely impacted ecosystem may be difficult or impossible to determine with accuracy.
Nevertheless, the general direction and boundaries of that trajectory can be established through a combination of knowledge of the damaged ecosystemís pre-existing structure, composition, and functioning; studies on comparable intact ecosystems; information about regional environmental conditions; and analysis of other ecological, cultural, and historical reference information. These combined sources allow the historical trajectory or reference conditions to be charted from baseline ecological data and predictive models, and emulation of these reference conditions in the restoration process should aid in piloting the ecosystem toward integrity (Society for Ecological Restoration 2004)