Drought-tolerant species thrive despite returning rains in the Sahel
Following the devastating droughts in the 70s and 80s in the Sahel region south of the Sahara desert, vegetation has now recovered. What surprise the researchers is that although it is now raining more and has become greener, it is particularly the more drought resistant species that thrive instead of the tree and shrub vegetation that has long been characteristic of the area. This is shown in a study from Stockholm University published in the journal Land Use Policy. The conclusion is that not only rain but also agriculture and human utilization of trees, bushes and land affect the plants recovering.
The expected pattern is that a drier climate favours drought resistant species, and that a wetter climate makes it possible for species that require more rainfall to thrive. A new study, however, shows the opposite effect; that a shift to more drought tolerant species is occurring, even though it's raining more. This shows that the recent regreening of the Sahel region can not only be explained by the fact that it rains more, which until now has been the dominant explanation.
"What we see is the beginning of a fairly dramatic change in the traditional agroforestry landscape in the area. Although it is not yet possible to say exactly what the consequences are for local livelihood and conservation, these are important issues that we will continue to work with. By, for example, examining what people in the area use different trees and shrubs for and look at how the landscape changes, we can better understand how land use, social change, climate and ecosystems interact, even in ways that can be unexpected", says Lowe Börjeson, Associate Professor at the Department of Human Geography, Stockholm University.
The study suggests that an understanding of how human use of the landscape interact with climate and ecosystem processes is important for organizations that want to develop strategies for climate change adaptation, biodiversity conservation and local development in one of the world's poorest regions.
Facts about the Sahel region
The Sahel is a semi-arid belt of land in Africa south of the Sahara and north of the wetter areas to the south. The Sahel extends east from the Atlantic Ocean through northern Senegal, southern Mauritania, Mali, Burkina Faso, southern Niger, northeastern Nigeria, Chad and the Sudan. Most of the Sahel region consists of savannah.
The recurrent droughts in the 1970s and 1980s had disastrous consequences for agriculture, livestock and the environment in the area, with widespread famine as a result. The drought in the region also gave rise to a global discussion and concern for desertification as an emerging environmental problem. In recent years, research has shown that the area since the 1980s, has instead become greener aw the vegetation has recovered.
More information: Hendrik Hänke et al. Drought tolerant species dominate as rainfall and tree cover returns in the West African Sahel, Land Use Policy (2016). DOI: 10.1016/j.landusepol.2016.08.023
Provided by Stockholm University