The ephemerality of secondary forests in southern Costa Rica

Secondary forests are increasingly recognized for conserving biodiversity and mitigating global climate change, but these and other desired outcomes can only be achieved after decades of regeneration, and secondary forests are frequently recleared before they recover to predisturbance conditions. We used a time series of aerial photographs (1947-2014) to evaluate multidecadal persistence of secondary forests across a 320 km(2) landscape in southern Costa Rica. Secondary forests had relatively short lifespans, with 50% recleared within 20 years and 85% recleared within 54 years of when they were first observed. Larger forest fragments and forests near rivers had a lower reclearance hazard, but forest persistence did not differ over time, indicating that regional forest regeneration may be generally ephemeral. Costa Rica has made an international commitment to restore 1 million ha of degraded land by 2020. Depending on how this is achieved, only half that target may remain forested by 2040.