The Sahel region is
becoming greener, but in unexpected ways
The Sahel region south of the Sahara desert is well known
for the disastrous droughts that struck the region in the 1970s and 1980s, which
ignited global concerns about a remorselessly advancing desert perpetuated by
unsustainable farming practices. New climate data shows, however, that the
decline in rainfall during the 1970s and 1980s was, in a global historical
perspective, an exceptionally rapid and enduring climatic event. The recovery
in rainfall since the crisis period is thus expected to be accompanied by a regreening
(returning vegetation) of Sahelian landscapes. Such a regreening is also
documented for the region. However, as a recently published study by Hendrik Hänke
and co-authors based on a case study from northern Burkina Faso shows, it is
not the same trees and bushes that returns in the landscape. Instead, a new mix
of more drought tolerant species dominates and many previously common trees are
in decline. This is an important, surprising and somehow paradoxical finding, as
more rain is not expected to stimulate a shift to trees and bushes that are
adapted to a drier climate. Hence, the results works against the logic that more
rain will allow more moisture demanding vegetation to grow. How is this
possible? The answer is that not only the amount of rainfall, but also human
land use practices, has a decisive effect on what trees and bushes thrive in a
specific environment. This conclusion challenges the dominant scientific
understanding of the Sahelian regreening as almost exclusively driven by
returning rainfall, and points at the importance of a better understanding of
how changing social-ecological relations may replace traditional agroforestry
landscapes with new a new mix of trees and bushes. Such a nuanced understanding
provide an important basis for any organization that wishes to design suitable
policies for climate change adaptation, biodiversity conservation and the sustainable
delivery of ecosystem services that benefit local livelihoods in one of the
world’s poorest regions.
Graphical abstract
A conceptual model illustrating different tree cover
pathways in relation to species composition and rainfall variability. The diagram
could be interpreted along any, even small, shifts along these gradients. Wet
and dry habitat indicates species thriving under relative wetter to dryer
conditions. Brown and green refers to a sparse and dense woody vegetation
cover, respectively.
The article is available here: https://doi.org/10.1016/j.landusepol.2016.08.023
