others who believe that protected areas should have the bare minimum of human interference, such as rewilding. Ecosystem restoration has generated controversy. Skeptics doubt that the benefits justify the economic investment or who point to failed restoration projects and question the feasibility of restoration altogether. It can be difficult to set restoration goals, in part because, as Anthony Bradshaw claims, "ecosystems are not static, but in a state of dynamic equilibrium…. [with restoration] we aim [for a] moving target." Some conservationists argue that, though an ecosystem may not be returned to its original state, the functions of the ecosystem (especially ones that provide services to us) may be more valuable in its current configuration (Bradshaw 1987). This is especially true in cases where the ecosystem services are central to the physical and cultural survival of human populations, as is the case with many Native groups in the United States and other communities around the world who subsist using ecological services and environmental resources. One reason to consider ecosystem restoration is to mitigate climate change through activities such as afforestation. Afforestation involves replanting forests, which remove carbon dioxide from the air. Carbon dioxide is a leading cause of global warming (Speth, 2005) and capturing it would help alleviate climate change. Another example of a common driver of restoration projects in the United States is the legal framework of the Clean Water Act, which often requires mitigation for damage inflicted on aquatic systems by development or other activities. Challenges Some view ecosystem restoration as impractical, partially because restorations often fall short of their goals. Hilderbrand et al. point out that many times uncertainty (about ecosystem functions, species relationships, and such) is not addressed, and that the time-scales set out for 'complete' restoration are unreasonably short, while other critical markers for full-scale restoration are either ignored or abridged due to feasibility concerns. In other instances an ecosystem may be so degraded that abandonment (allowing a severely degraded ecosystem to recover on its own) may be the wisest option. Local communities sometimes object to restorations that include the introduction of large predators or plants that require disturbance regimes such as regular fires, citing threat to human habitation in the area. High economic costs can also be perceived as a negative impact of the restoration process. Public opinion is very important in the feasibility of a restoration; if the public believes that the costs of