Ecological restoration

Ecological restoration, or ecosystem restoration, is the process of assisting the recovery of an ecosystem that has been degraded, damaged, destroyed or transformed. It is distinct from conservation in that it attempts to retroactively repair already damaged ecosystems rather than take preventative measures. Ecological restoration can help to reverse biodiversity loss, combat climate change, support the provision of ecosystem services and support local economies. The United Nations has named 2021–2030 the Decade on Ecosystem Restoration.

Habitat restoration involves the deliberate rehabilitation of a specific area to reestablish a functional ecosystem. This may differ from historical baselines (the ecosystem's original condition at a particular point in time). To achieve successful habitat restoration, it is essential to understand the life cycles and interactions of species, as well as the essential elements such as food, water, nutrients, space, and shelter needed to support species populations.

Scientists estimate that the current species extinction rate, or the rate of the Holocene extinction, is 1,000 to 10,000 times higher than the normal, background rate. Habitat loss is a leading cause of species extinctions and ecosystem service decline. Two methods have been identified to slow the rate of species extinction and ecosystem service decline: conservation of quality habitat and restoration of degraded habitat. The number and size of ecological restoration projects have increased exponentially in recent years, with hundreds of thousands of projects across the globe.

Restoration goals reflect political choices, and differ by place and culture. On a global level, the concept of nature-positive has emerged as a societal goal to achieve full nature recovery by 2050, including through restoration of degraded ecosystems to reverse biodiversity loss.

The Society for Ecological Restoration defines restoration as "the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed." Restoration ecology is the academic study of the science of restoration, whereas ecological restoration is the implementation by practitioners. Ecological restoration includes a wide diversity of methods including erosion control, reforestation, removal of non-native species and weeds, revegetation of disturbed areas, daylighting streams, the reintroduction of native species, habitat and range improvement for targeted species and establishing wildlife corridors. Many scholars and practitioners argue that ecological restoration must include local communities and stakeholders: they call this process the "social-ecological restoration".

The goal of ecosystem restoration depends on the specific context of each location. Traditionally, the aim has been to return ecosystems to a past state (historic baseline), based on the idea that past conditions represent a 'pristine' or ideal functioning state. However, this approach is now questioned because human-driven environmental changes, including climate change, continuously alter ecosystems, resulting in a shifting baseline. Today, it's widely recognized that there may be several possible targets for restoration, based on a range of factors. Targets are set based on factors such as the level of ecosystem degradation, how much ecosystem functionality can realistically be restored, local community views, and the costs of restoration efforts.

There are many reasons to restore ecosystems. Some include:

There are considerable differences of opinion on how to set restoration goals and define their success. As Laura J. Martin writes, "Restoration targets are moral and political matters as well as logistical and scientific ones." Some restorationists urge active restoration (e.g. killing invasive animals) and others believe that protected areas should have the bare minimum of human interference, such as rewilding.