The complete recovery of biodiversity after restoration: fact or fancy?

After centuries of environmental degradation, global efforts have increasingly focused on ecological restoration as a strategy to recover damaged ecosystems. Restoration initiatives employ diverse methods and metrics to evaluate success, typically comparing restored areas with reference ecosystems. A central challenge in this process is determining how biodiversity recovery should be measured and what outcomes are achievable. Evidence suggests that biodiversity tends to increase during the early stages of natural regeneration, but research studies indicate that restored ecosystems never reach the biodiversity levels of mature reference forests. Long‐term studies show that even after several decades of natural regeneration, diversity remains lower than in undisturbed areas, and tree species composition may still differ significantly even after more than a century. The situation may be more constrained in actively restored forests, where restoration projects often use only a small fraction of the tree species in the reference areas. Therefore, restoration processes may also lead to ecological homogenization. Additionally, secondary forests generally fail to match the carbon storage capacity of mature forests, reinforcing the irreplaceable ecological value of intact ecosystems.