Unmanaged naturally regenerating forests approach intact forest canopy structure but are susceptible to climate and human stress

Maintaining newly re-established forests is an important policy and challenge for ecosystem restoration and climate-change mitigation. However, a global assessment of canopy structure in regenerating forests under different management and whether they are developing toward that of intact forests is lacking, impeding the understanding of their roles in carbon cycling and biodiversity recovery. Here we present the first near-global assessment of regenerating forest canopy structure at a 1-km resolution and its progress toward attaining intact forest characteristics. We show that canopy structure in unmanaged naturally regenerating forests more closely resemble intact forests than managed naturally regenerating forests and planted forests, but they are more susceptible to climate and human stress. Meanwhile, managed naturally regenerating forests experience substantial re-clearance. Our findings underscore the high ecological recovery potential of naturally regenerating forests and call for urgent action to enhance socio-ecological conditions for their persistence, unlocking their potential in sustainable development.