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When and where to protect forests


Ongoing deforestation poses a major threat to biodiversity1,2. With limited resources and imminent threats, deciding when as well as where to conserve is a fundamental question. Here we use a dynamic optimization approach to identify an optimal sequence for the conservation of plant species in 458 forested ecoregions globally over the next 50 years. The optimization approach includes species richness in each forested ecoregion, complementarity of species across ecoregions, costs of conservation that rise with cumulative protection in an ecoregion, the existing degree of protection, the rate of deforestation and the potential for reforestation in each ecoregion. The optimal conservation strategy for this formulation initially targets a small number of ecoregions where further deforestation leads to large reductions in species and where the costs of conservation are low. In later years, conservation efforts spread to more ecoregions, and invest in both expanded protection of primary forest and reforestation. The largest gains in species conservation come in Melanesia, South and Southeast Asia, the Anatolian peninsula, northern South America and Central America. The results highlight the potentially large gains in conservation that can be made with carefully targeted investments.

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Fig. 1: Forested ecoregions with conservation spending resulting in additional species protection over the 50-year planning horizon with an annual budget of US $1 billion.
Fig. 2: Optimal conservation strategy: determinants and comparison with heuristics.

Data availability

Data used for the analysis in this paper can be found at Zenodo: data are provided with this paper.

Code availability

Code for this paper can be found at Zenodo: data are provided with this paper.


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We thank P. Armsworth, M. Burgman and members of his laboratory group, J. Fargione, E. Game, K. Helmstedt and G. Iacona for their comments on the manuscript; S. Andelman, J. Bielecki, M. Bode and H. Possingham for early discussions and development of the ideas; and J. Smith for help on addressing species complementarity.

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Authors and Affiliations



S.P. conceived the original idea. All authors devised the theoretical method and application. I.L. and S.J.M. collected and analysed the data and S.J.M. performed the numerical optimizations. All authors wrote the manuscript and participated in in the discussion and interpretation of the results, and the determination of the conclusions.

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Correspondence to Ian H. Luby.

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Nature thanks Ian Bateman, Laura Pollock, Henrique Pereira and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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Luby, I.H., Miller, S.J. & Polasky, S. When and where to protect forests. Nature 609, 89–93 (2022).

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