Species → Blue Wildebeest
Blue Wildebeest
Connochaetes taurinus
What if it disappeared?
Impact MajorWhen rinderpest was decimating Serengeti wildebeest before the 1960s, ungrazed grass fueled more extensive brush fires and blocked tree recruitment. After the disease was eradicated in surrounding livestock, the wildebeest population grew from about 250,000 to over a million individuals within about fifteen years — this return of grazing markedly reduced the extent of fires and allowed massive tree recruitment, proof by omission of what wildebeest contribute in numbers.
DocumentedDetail
Holdo, R.M., Sinclair, A.R.E. et al. (2009). A disease-mediated trophic cascade in the Serengeti and its implications for ecosystem carbon. PLoS Biology, 7(9), e1000210.
The study reconstructs the dynamics over decades from aerial censuses, fire surveys, and tree-density measurements. The model identifies wildebeest abundance and within-year rainfall variation as the best predictors of fire occurrence, with fire itself the main driver of the observed changes in tree density — a cascade in which herbivory indirectly suppresses fire, which in turn allows woody regeneration.
If wildebeest were to disappear from the Serengeti again as they did before the 1960s, the ecosystem could revert to being the net carbon source it once was, rather than the net sink it has become — currently drawing down on the order of a million tonnes of carbon a year from the atmosphere — but this figure rests on an assumption current data cannot directly verify.
ExtrapolatedDetail
Même étude, Holdo & Sinclair et al. 2009, PLoS Biology — les auteurs distinguent explicitement ce volet comme modélisé plutôt que mesuré.
The authors say so themselves: lacking repeated data on the size-class distribution of trees, they must assume carbon stocks are directly proportional to observed tree density alone. The wildebeest population reconstruction and the fire-tree relationship rest on solid, multiple data sources; the resulting carbon-sink figure remains, by the authors' own admission, an extrapolation.
What's missing to confirm it: Repeated monitoring of the size-class distribution (not just the density) of Serengeti trees would make it possible to verify the true scale of the carbon sink rather than infer it from a proportionality assumption.
Documentation
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Holdo, Sinclair et al. (2009) — A disease-mediated trophic cascade in the Serengeti and its implications for ecosystem carbon, PLoS Biology
Accessed August 7, 2026
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PMC — texte intégral de l'étude Holdo et al. 2009
Accessed August 7, 2026
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Wikipedia (synthèse sourcée IUCN) — Blue wildebeest, statut et population
Accessed August 7, 2026
Last verified: August 14, 2026