The early/late fire dichotomy: Time for a reassessment of Aubreville's savanna fire experiments

A fundamental principal of savanna fire ecology is that the fire regime determines vegetation cover, especially as it pertains to trees. A corollary is that late fires are more damaging to trees than early fires. Much evidence in support of this principle has been derived from a series of long-term burning experiments based on the pioneering work of Andre Aubreville. Eighty years ago, Aubreville devised an experiment to study the impacts of fire on savanna trees in Africa. The design conventions of this study remain highly influential. It is now clear, however, that the dates chosen by Aubreville and his followers do not reflect the burning practices of West African people. Dates that were chosen for early and late are not representative of actual fire timing; they represent extremes. This study has four goals: (i) to critically review the results of the burning experiments; (ii) to examine them in the context of results from recent savanna fire studies; (iii) to evaluate their limitations based on data for actual burning practices and fires from West Africa; and (iv) to critically evaluate the use of the early/late terminology in contemporary fire research. We find the majority of West African fires occur during the middle of the fire season. Our field studies find that fire temperature and burn completeness are highest in the middle-season. We conclude that the early/late fire dichotomy is not sufficient for understanding the impacts of anthropogenic fires in the region and we make suggestions for rethinking its use more broadly.