Although natural regeneration can be ecologically effective in the right environmental and socio-economic contexts, the importance of the Bonn Challenge should not be downplayed (see S. L. Lewis et al. Nature 568, 25–28; 2019). Its aim is to promote the recovery of degraded and deforested lands (see go.nature.com/2jc5it3), rather than solely to mitigate climate change, as the authors imply.

Some of the land pledged in response to the challenge will consist of plantations, but not to the extent suggested by the authors. Brazil, for example, is committed to regenerating 12 million hectares (not 19 million hectares), which includes restoration of native forest as well as new plantations. Also, given that restoration must accommodate a multiplicity of needs, including those of smallholder farmers, we disagree that agroforestry should be confined to treeless regions. And some agroforestry systems use native species for restoration — Evergreen Agriculture integrates crops with Faidherbia albida trees, for example.