A drained wetland becomes a housing development. Twenty years later, ecologists breach the levees, replant the sedges, and wait. Restoration is the attempt to bring a degraded ecosystem back to something like its former state. It is slow, expensive, and rarely complete.

The science behind it has matured since the 1980s. Practitioners now talk about reference sites: nearby intact ecosystems used as benchmarks for species composition, hydrology, and soil chemistry. You cannot just plant trees and walk away. You have to restore the processes that keep them alive, like seasonal flooding, fire regimes, or pollinator populations.

Common restoration targets

• Wetlands drained for agriculture
• Mine sites stripped of topsoil
• Rivers straightened into canals
• Grasslands invaded by non-native species

The Knepp Estate in England is a well-known example. Once intensive farmland, it was left to rewild with minimal intervention. Storks, beavers, and purple emperor butterflies returned. Not every project goes that well. Some restored sites never recover their original species. Restoration is an attempt, not a guarantee. The honest ones measure success against realistic goals, not nostalgia.