More than one quarter of Africa’s tree cover is found outside areas previously classified as forest

Florian Reiner (1) , Martin S. Brandt (1) , Xiaoye Tong (1) , David L. Skole (2) , Ankit Kariryaa (1) , Philippe Ciais (3) , Andrew B. Davies (4) , Pierre H.Y. Hiernaux (5) , Jérôme Chave (6) , Maurice Mugabowindekwe (1) , Christian Igel (1) , Stefan Oehmcke (1) , Fabian Cristian Gieseke (1, 7) , Sizhuo Li (8) , Siyu Liu (1) , Sassan S. Saatchi (9) , Peter Brehm Boucher (4) , Jenia Singh (4) , Simon Taugourdeau (10) , Morgane Dendoncker (11) , Xiaopeng Song (12) , Ole Mertz (1) , Compton James Tucker (13) , R. Fensholt (1)

1 UCPH - University of Copenhagen = Københavns Universitet
2 Michigan State University [East Lansing]
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 Harvard University
5 PastoC - Pastoralisme Conseil
6 UT3 - Université Toulouse III - Paul Sabatier
7 WWU - Westfälische Wilhelms-Universität Münster = University of Münster
8 SOURCE - SOUtenabilité et RésilienCE
9 CALTECH - California Institute of Technology
10 UMR SELMET - Systèmes d'élevage méditerranéens et tropicaux
11 UCL - Université Catholique de Louvain = Catholic University of Louvain
12 University of Maryland [College Park]
13 GSFC - NASA Goddard Space Flight Center

The consistent monitoring of trees both inside and outside of forests is key to sustainable land management. Current monitoring systems either ignore trees outside forests or are too expensive to be applied consistently across countries on a repeated basis. Here we use the PlanetScope nanosatellite constellation, which delivers global very high-resolution daily imagery, to map both forest and non-forest tree cover for continental Africa using images from a single year. Our prototype map of 2019 (RMSE = 9.57%, bias = −6.9%). demonstrates that a precise assessment of all tree-based ecosystems is possible at continental scale, and reveals that 29% of tree cover is found outside areas previously classified as tree cover in state-of-the-art maps, such as in croplands and grassland. Such accurate mapping of tree cover down to the level of individual trees and consistent among countries has the potential to redefine land use impacts in non-forest landscapes, move beyond the need for forest definitions, and build the basis for natural climate solutions and tree-related studies.

Mots clés: TROPICAL FOREST; SAVANNAS

Domaines: Sciences du Vivant [q-bio]

Florian Reiner, Martin S. Brandt, Xiaoye Tong, David L. Skole, Ankit Kariryaa, et al.. More than one quarter of Africa’s tree cover is found outside areas previously classified as forest. Nature Communications, 2023, 14 (1), ⟨10.1038/s41467-023-37880-4⟩. ⟨hal-04106270⟩