Long-term frequent fires do not decrease topsoil carbon and nitrogen in an Afromontane grassland

Contrary to expectations, long-term frequent fires do not decrease topsoil carbon and nitrogen in Afromontane grasslands of the Maloti-Drakensberg Park. Instead, annual spring burning significantly increased soil organic carbon (SOC) and nitrogen (SON), with an average C sequestration rate of 0.30 Mg ha⁻¹ y⁻¹ across all treatments. This unexpected finding is attributed to the aluandic properties of Drakensberg soils, which are acidic and high in organic matter. The study compared SOC and SON from six fire regimes (annual, biennial, five-year, infrequent) with varying seasons over a 39-year period, revealing that autumn burning did not yield similar increases. Infrequently burnt plots exhibited the lowest carbon stocks, highlighting the importance of fire season in shaping soil organic matter dynamics.

Findlay, N., Manson, A., Cromsigt, J. P., Gordijn, P., Nixon, C., Rietkerk, M., Thibaud, G., Wassen, M. J., & Beest, M. t. (2022). Long-term frequent fires do not decrease topsoil carbon and nitrogen in an Afromontane grassland. African Journal of Range & Forage Science, 39(1), 44–55. https://doi.org/10.2989/10220119.2021.2016966