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 km² 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.

中文翻译：

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哥斯达黎加南部次生林的短暂性

次生林在保护生物多样性和缓解全球气候变化方面得到越来越多的认可，但是这些和其他期望的结果只有在几十年的再生之后才能实现，并且次生林在恢复到扰乱前的状况下经常被清除。我们使用了一系列的航拍照片（1947-2014年）来评估320 km ²范围内次生林的数十年持久性哥斯达黎加南部的自然景观。次生林的寿命相对较短，初次观察时，在20年内砍伐了50％，在54年内砍伐了85％。较大的森林碎片和河流附近的森林具有较低的清除风险，但随着时间的推移，森林的持久性并没有不同，这表明区域性森林的更新通常可能只是短暂的。哥斯达黎加做出了一项国际承诺，到2020年恢复100万公顷的退化土地。根据实现的方式，到2040年，只有一半的目标仍可保持森林。