COS 159-2 - CANCELLED - Proximity to natural forest failed to rescue a declining agroforestry tree species

Background/Question/Methods

The conservation of species in human-modified landscapes such as agroforestry systems is central to global biological diversity conservation and sustainable use. Understanding the dynamics of key species in agroforestry systems is important for predicting the sustainability of these systems. However, the dynamics of agroforestry tree species are often unknown, and planning for the management of these systems is generally grounded on the untested assumption that the tree component will persist over time. Here, we developed an integral projection model for shea butter tree species, the most important tree component of traditional agroforestry systems in West Africa. We collected three years of demographic data from six populations around the Pendjari Biosphere Reserve to parameterize this model and test the effect of populations’ proximity to natural habitats on the short- and long-term dynamics of shea butter trees.

Results/Conclusions

We found no significant effect of proximity on the long-term population dynamics. However, models suggest that the populations are declining at a rate of 10.6% yearly and within the next two decades, this tree will be locally extinct. Elasticity analyses show that the best strategy to slow down such a decline includes preserving the largest mature trees. However, traditional management systems that protect shea butter trees in agroforestry systems are now replaced by increasing cutting of the species to produce firewood and charcoal. The decline of this key agroforestry tree poses a broader threat to long-term sustainability of the agroforestry systems.