Habitat Restoration is the act of using biological and ecological principles to return a severely human-impacted area to its pre-colonization state. Usually this consists of removing alien species of plants and planting natives, however it also may consist of restoring hydrological regimes, removing debris, introducing animals, etc. It is linked with the bioregionalism movement and is becoming popular in many ecologically sensitive areas. Sometimes the government requires a developer to do restoration in exchange for land he is destroying, in a process known as mitigation.