What Ever Happened to Neem Decline in the Sahel?

Abstract

Neem is planted extensively in the Sahel and is a vital species in a region where harsh conditions provide limited options for planting trees. The reputation of neem as a valuable option for agroforestry was significantly damaged by reports of a steady decline of trees in Niger, first noted in 1990. Short-term studies up to 1996 quickly established that neem decline was also present in northern Nigeria, Chad and Cameroon. The decline prompted the creation of the International Neem Network and the establishment of provenance trials for genetic improvement. No evidence was found for association with a pest or pathogen and neem decline became yet another poorly understood tree disorder of abiotic origin. There is some evidence to link neem decline to a prolonged drought in the Sahel even though such events had occurred before the 1990s without any reports of any similar effects on neem. There have been no further reports of neem decline in the Sahel or elsewhere, though there is increasing evidence that trees do not thrive in single stands. Neem decline may have dented the reputation of neem yet the tree is still popular in 2023. It would be wrong to assume that neem decline will never resurface in the current climate crisis. © The Author 2024