Managing forest regeneration and expansion at a time of unprecedented global change

Forests provide fundamental ecosystems services to mitigate climate change and support biodiversity but they are seriously threated by local human pressures and the outcomes of global climate change (Trumbore et al., 2015). According to FAO estimates, some 420 million hectares of forest have been lost since 1990, although the rate of deforestation has decreased over the past three decades from 16 × 106 ha/year in the 1990s to 10 × 106 ha/year from 2015 to 2020 (FAO, 2020). There is, however, broad agreement that deforestation still prevails in the tropics, whereas extratropical regions tend to gain in forest cover as rural lands become depopulated, abandoned and recolonized by forest species (Chazdon, 2014; García et al., 2014). Consequently, the proportion of second-growth forests—that is, forest or woodland areas that have re-established after the complete loss of the original tree cover—is rapidly increasing across both hemispheres.