Africa is forecasted to experience large and rapid climate change1 and population growth2 during the twenty-first century, which threatens the world’s second largest rainforest. Protecting and sustainably managing these African forests requires an increased understanding of their compositional heterogeneity, the environmental drivers of forest composition and their vulnerability to ongoing changes. Here, using a very large dataset of 6 million trees in more than 180,000 field plots, we jointly model the distribution in abundance of the most dominant tree taxa in central Africa, and produce continuous maps of the floristic and functional composition of central African forests. Our results show that the uncertainty in taxon-specific distributions averages out at the community level, and reveal highly deterministic assemblages. We uncover contrasting floristic and functional compositions across climates, soil types and anthropogenic gradients, with functional convergence among types of forest that are floristically dissimilar. Combining these spatial predictions with scenarios of climatic and anthropogenic global change suggests a high vulnerability of the northern and southern forest margins, the Atlantic forests and most forests in the Democratic Republic of the Congo, where both climate and anthropogenic threats are expected to increase sharply by 2085. These results constitute key quantitative benchmarks for scientists and policymakers to shape transnational conservation and management strategies that aim to provide a sustainable future for central African forests.
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All maps and data used for this article are accessible online in a public repository at https://doi.org/10.18167/DVN1/UCNCA7. Raw floristic data are, however, archived in a private data repository, owing to the highly sensitive nature of commercial inventory data, and access may be granted for research purposes using the form provided in the public repository.
R scripts are available at https://github.com/MaximeRM/ScriptNature.
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We thank the 105 forest companies that provided access, albeit restricted, to their inventory data for research purposes and members of the central African plot network (https://central-african-plot-network.netlify.app/), Y. Yalibanda, F. Allah-Barem, F. Baya, F. Boyemba, M. Mbasi Mbula, P. Berenger, M. Mazengue, V. Istace, I. Zombo, E. Forni, Nature+ and the CEB-Precious Woods company for giving access to the scientific inventories described in Supplementary Fig. 4, some of which were funded by the AFD and the FFEM (for example, DynAfFor and P3FAC projects). We thank J. Chave, P. Couteron, S. Lewis and M. Tadesse for their comments and discussions on previous versions, B. Sultan for useful discussions on climate projections, O. J. Hardy for advice on phylogenetical analyses, B. Locatelli for advice on vulnerability analyses, G. Vieilledent for discussions on the human-induced forest-disturbance intensity index and A. Stokes for English editing. This work was supported by the CoForTips project (ANR‐12‐EBID‐0002) funded by the ERA-NET BiodivERsA, with the national funders ANR, BELSPO and FWF, as part of the 2012 BiodivERsA call for research proposals, the GAMBAS project funded by the French National Research Agency (ANR-18-CE02-0025) and the project 3DForMod funded by the UE FACCE ERA-GAS consortium (ANR-17-EGAS-0002-01). This study is a contribution to the research program of LMI DYCOFAC (Dynamique des écosystèmes continentaux d’Afrique Centrale en contexte de changements globaux).
The authors declare no competing interests.
Peer review information Nature thanks Jonas Geldmann, Marion Pfeifer, Philip Platts and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
In green, the current distribution of tropical forests following the ESA-CCI landcover product (v.1.6), with a dark-green-to-white gradient representing anthropogenic pressure (see Methods) and non-forested areas represented in beige. The sampling grid cells (n = 1,571 10 × 10-km2 grid cells) are in black and the flooding forests, as proposed by the ESA-CCI landcover, are in blue.
a, CC1 and CC2. b, CC1 and CC3. c, CC2 and CC3. All climatic variables with a correlation of less than 0.75 with the two components (dashed circle) were excluded for the sake of clarity. For abbreviations, see Extended Data Table 2.
a–c, The observed and predicted community weighted mean trait values within the 1,571 10x10-km2 grid cells are given for wood density (a), deciduousness (b) and maximum diameter (c). The 1:1 line is displayed in red.
Extended Data Fig. 6 Projected changes under the RCP 4.5 scenario in 2085 of the climatic conditions of the 10 forest types.
Areas for which climate models predict similar climatic components (CCs) values to those currently found within forest types (in black) are illustrated with a colour gradient indicating the level of agreement amongst the 18 climate models (as a percentage; no colour indicates that none of the original 18 climate models predicted similar conditions). More specifically, we used 3D concave hull (alpha shape) models to assess where the combinations of current CCs corresponding to each forest type are predicted to be represented in 2085.
Extended Data Fig. 7 The vulnerability map under two different RCP scenarios and for two different years.
a–d, Vulnerability maps under RCP 4.5 in 2055 (a), RCP 8.5 in 2055 (b), RCP 4.5 in 2085 (c) and RCP 8.5 in 2085 (d). As can be seen, the predicted vulnerability is little affected by the IPCC scenario chosen because it expresses a relative vulnerability over the study area and, if different scenarios predict different amplitudes of climate change, spatial patterns of climate exposure remains similar (see Methods).
a, b, Current (a) and projected (b) anthropogenic pressure predicted from our index of human-induced forest-disturbance intensity.
Extended Data Fig. 9 Protected area network and areas dedicated to logging activities in central Africa.
The protected area network is shown in blue; areas dedicated to logging are shown in orange and red. Data on protected areas were obtained from the World Database on Protected Areas (https://www.iucn.org/theme/protected-areas/our-work/world-database-protected-areas, last accessed 14 August 2018), excluding marine, hunting and game-oriented areas, except for the Democratic Republic of the Congo, for which data from the World Resource Institute were used and downloaded from ArcGIS hub (https://hub.arcgis.com/datasets/1bcd463cbb6549c9a0676edb9f751f9b, last accessed 1 June 2019). Logging activity data were provided by the Observatoire des Forêts d’Afrique Centrale based on an unpublished work completed in June 2018, except for the Democratic Republic of the Congo, for which more updated data (June 2019) were provided by the AGEDUFOR national project. Areas in orange illustrate forest concessions that are known to have, or to be in the process of having, an officially validated sustainable forest management plan. Red areas illustrate forest areas that are currently dedicated to logging but that either do not have an official management plan or have an uncertain status.
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Réjou-Méchain, M., Mortier, F., Bastin, JF. et al. Unveiling African rainforest composition and vulnerability to global change. Nature 593, 90–94 (2021). https://doi.org/10.1038/s41586-021-03483-6