Abstract
After the severe droughts in the 1970s and 1980s, and subsequent debates about desertification, analyses of satellite images reveal that the West African Sahel has become greener again. In this paper we report a study on changes in tree cover and tree species composition in three village landscapes in northern Burkina Faso, based on a combination of methods: tree density change detection using aerial photos and satellite images, a tree species inventory including size class distribution analysis, and interviews with local farmers about woody vegetation changes. Our results show a decrease in tree cover in the 1970s followed by an increase since the mid-1980s, a pattern correlating with the temporal trends in rainfall as well as remotely sensed greening in the region. However, both the inventory and interview data shows that the species composition has changed substantially towards a higher dominance of drought-resistant and exotic species. This shift, occurring during a period of increasing annual precipitation, points to the complexity of current landscape changes and questions rain as the sole primary driver of the increase in tree cover. We propose that the observed changes in woody vegetation (densities, species composition and spatial distribution) are mediated by changes in land use, including intensification and promotion of drought tolerant and fast growing species. Our findings, which indicate a rather surprising trajectory of land cover change, highlight the importance of studies that integrate evidence of changes in tree density and species composition to complement our understanding of land use and vegetation change trajectories in the Sahel obtained from satellite images. We conclude that a better understanding of the social-ecological relations and emerging land use trajectories that produce new types of agroforestry parklands in the region is of crucial importance for designing 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.
Highlights
In a global perspective, the decline in rainfall over the Sahel during the 1970s and 1980s stands out as a dramatic change in decadal means
SCD- analysis To evaluate changes in tree species composition over time, we looked at the size class distribution (SCD) for each tree species inventoried in the larger sampling plots
Our results show that the increase in tree cover has been accompanied by a change in tree species composition from a typical Sahelian agroforestry parkland flora towards a tree flora dominated by drought resistant and exotic species, and more shrubs
Summary
The decline in rainfall over the Sahel during the 1970s and 1980s stands out as a dramatic change in decadal means. Rainfall isohyets shifted 1–2 ◦ of latitude as compared to the wetter conditions during the 1930s to 1960s (Nicholson, 2013). The drought’s disastrous effects on livelihoods and land use systems have received much attention from media, science, policy and civil society, and gave rise to extensive debates about desertification (Behnke and Mortimore, 2016; UNCCD, 1994). While desertification remains an influential science and policy framework, shaping e.g. climate change adaptation strategies (Mortimore and Turner, 2005; O’Connor and Ford, 2014), a different process of Sahelian environmental change has made the headlines more recently, as the region is reported to have become greener again since the 1980s (Brandt et al, 2015; Eklundh and Olsson, 2003; Herrmann et al, 2005; Kaptué et al, 2015). Hänke et al / Land Use Policy 59 (2016) 111–120
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
