There are few ecosystems in the world that have not been impacted by humans. Humans can eliminate species and disrupt natural processes, degrading or even destroying complex local webs of life. Ecological restoration is human facilitation of the repair of a damaged or destroyed ecosystem. Restored environments may take years to function without human intervention and may never be the same as their intact predecessors, but restoration remains an important part of the conservation toolbox.
There are different ways to measure restoration and determine when the work is done. The focus can be on species assemblages, ecosystem processes, disturbance regimes, resiliency or the trajectory of the environment. Restoration can also be measured by the absence of such factors as evidence of dysfunction or the need for human maintenance. Ultimately, the restored project is compared to a reference ecosystem, which could be the same location in the past or a similar intact system.
Typically, degraded ecosystems are missing species, groups of species, or even whole functional groups, such as top-level predators. Sowing native seeds or transplanting individual plants is one step in restoring biodiversity. Restoration projects may include reintroducing large vertebrates, such as bison in American prairie redevelopment. Bison are a keystone species with such broad impacts that the ecosystem cannot function in the same way without them. Other examples of keystone species include prairie dogs on high plains and starfish in tidal pools.
Putting species back on the landscape can be like putting all of the pieces of a watch on a table and expecting it to work. There are complex interactions, such as resilient food webs and nutrient cycles, that need to resume in a restored environment. One way to restore function is to recreate disturbance regimes, or episodes of temporary environmental change, that encourage historical succession patterns. For example, setting controlled burns clears underbrush, and in some plants, encourages growth or seed dispersal. In rivers, releasing large amounts of water from a reservoir pushes sediments downstream.
Restored ecosystems tend to be small and isolated, making genetic diversity and the integration of the restored area into the landscape important considerations. Ensuring healthy genetic diversity requires drawing from as wide a genetic pool as possible. It also requires creating physical connections for travel that allow the exchange of genetic information across the landscape. In practice, creating corridors of habitat between isolated islands of intact and restored ecosystems restores connectivity.
How You Can Get Involved
Most restoration projects are done by experts, and you could join their ranks with graduate training in restoration ecology. You can also help out with restoration activities in your community. Many restorations involve labor-intensive activities like removing invasive species or collecting native seeds for planting, which are accomplished with the help of community volunteer groups. The Society for Ecological Restoration, for example, holds "Make A Difference Day" events in various communities. Check with your local natural resource agency, naturalist program, or university to locate a project near you.
- Nature: Restoration Ecology
- Restoration Ecology: A Synthetic Approach to Ecological Research; William R Jordan III, Michael E Gilpin, John D Aber
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