Burning poop: Chemical composition and carbon dynamics of large herbivore dung burned in African savanna fires

[Background] Fire and herbivores are essential to savanna ecosystems, consuming vegetation and recycling nutrients. Fire volatilises some elements and makes others readily available through ash, while herbivores redistribute nutrients via dung (excrement, faeces).

[Aims] We investigate, for the first time, fire’s role in consuming dung and affecting nutrient cycling.

[Methods] We examined the chemical characteristics of wild large herbivore dung (buffalo, elephant, giraffe, wildebeest, zebra) burned during African savanna fires (Kruger National Park, South Africa) and estimated carbon and nutrients losses from dung burning.

[Key results] Smouldering combustion of dung led to high carbon loss to the atmosphere (C: 41% and 4.1% in unburned and burned dung) and high enrichment of nutrients (e.g. Ca, P) and metals (e.g. Cu, Fe, Zn) in the burned residue. Flaming combustion of grass resulted in lower carbon loss (C: 43% and 23% in vegetation and ash), leaving more carbon in the ash and lower relative enrichment of other nutrients and metals.

[Conclusions] Burned dung forms nutrient hotspots with physicochemical characteristics distinct from vegetation ash.

[Implications] Taking dung from wild or domestic herbivores into account in fuel inventories can improve estimations of fire-related carbon emissions and provide better understanding of fire impacts on nutrients cycling.

During manuscript preparation C. Sánchez-García and S. H. Doerr received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101003890. Fieldwork was funded by The Leverhulme Trust (grant RPG-2014-095). Chemical analyses were supported by Natural Environment Research Council grant (NE/R011125/1) and by the Consellería de Educacion, Universidade e Formacion Profesional–Xunta de Galicia (Axudas á consolidacion e estruturacion de unidades de investigacion competitivas do SUG del Plan Galego IDT, Ambiosol Group ref. ED431C 2022/40).

Peer reviewed