Resistance of African tropical forests to an extreme climate anomaly

Citation

Bennett AC, Dargie GC, Cuni-Sanchez A, Mukendi JT, Hubau W, Mukinzi JM, Phillips OL, Malhi Y, Sullivan MJP, Cooper DLM, Adu-Bredu S, Affum-Baffoe K, Amani CA, Jeffery KJ & White LJT (2021) Resistance of African tropical forests to an extreme climate anomaly. Proceedings of the National Academy of Sciences, 118 (21), Art. No.: e2003169118. https://doi.org/10.1073/pnas.2003169118

Abstract
The responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015–2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015–2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha−1 y−1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.

Keywords
temperature; drought; ENSO; carbon cycle; El Niño

Notes
Additional co-authors: Lindsay F. Banin, Hans Beeckman, Serge K. Begne, Yannick E. Bocko, Pascal Boeckx, Jan Bogaert, Terry Brncic, Eric Chezeaux, Connie J. Clark, Armandu K. Daniels, Thales de Haulleville, Marie-Noël Djuikouo Kamdem, Jean-Louis Doucet, Fidèle Evouna Ondo, Corneille E. N. Ewango, Ted R. Feldpausch, Ernest G. Foli, Christelle Gonmadje, Jefferson S. Hall, Olivier J. Hardy, David J. Harris, Suspense A. Ifo, Elizabeth Kearsley, Miguel Leal, Aurora Levesley, Jean-Remy Makana, Faustin Mbayu Lukasu, Vincent P. Medjibe, Vianet Mihindu, Sam Moore, Natacha Nssi Begone, Georgia C. Pickavance, John R. Poulsen, Jan Reitsma, Bonaventure Sonké, Terry C. H. Sunderland, Hermann Taedoumg, Joey Talbot, Darlington S. Tuagben, Peter M. Umunay, Hans Verbeeck, Jason Vleminckx, Hannsjoerg Woell, John T. Woods, Lise Zemagho, and Simon L. Lewis

Journal
Proceedings of the National Academy of Sciences: Volume 118, Issue 21