Regenerating ecosystems are increasingly recognized for conserving biodiversity and mitigating global climate change, but these and other desired outcomes are contingent on a sufficient recovery time. Unfortunately, regenerating ecosystems are frequently re-cleared for agriculture or other land uses before they recover to pre-disturbance conditions. This observation raises two questions: (1) How long do regenerating ecosystems persist? and (2) Why do some persist for much longer than others? To approach these questions, we have reviewed literature, tracked site histories in an existing forest restoration experiment, surveyed restoration practitioners, and tracked regenerating forests using historical, aerial imagery in Costa Rica and Brazil.
Results/Conclusions
Our observations suggest that restored and regenerating ecosystems have a temporal dimension that is variable, often finite, and predictable to some extent based on the attributes of stakeholders, the local environment, and governance. For example, using historical, aerial imagery from 1947-2014 in a 320 km2 landscape in southern Costa Rica, we found that regenerating tropical forests had relatively short lifespans, with 50% of forest patches re-cleared within 20 years and 85% re-cleared within 54 years of when they were first observed. Riparian forests were at lower risk of re-clearance, as were secondary forests owned by foreigners – suggesting that the permanence of regenerating forests may be greater on agriculturally marginal lands, on lands protected from deforestation by legislation (i.e., riparian buffers), and when key stakeholders have a preference for natural ecosystems. Much remains to be learned about the permanence or ephemerality of regenerating ecosystems, but it is likely that decision makers and practitioners have considerable leverage to increase the probability that a restored ecosystem persists into the future.