LOCAL PERCEPTIONS OF WOODY VEGETATION DYNAMICS IN THE CONTEXT OF A ‘GREENING SAHEL’: A CASE STUDY FROM BURKINA FASO T. K. SOP* AND J. OLDELAND Biodiversity, Evolution and Ecology of Plants, Biocentre Klein Flottbek and Botanical Garden, University of Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany Received: 9 May 2011; Revised: 6 July 2011; Accepted: 13 July 2011 ABSTRACT After decades of drought in the Sahel, several studies have reported a ‘(re)greening’ of the area. However, most of these studies were based on large scale climatological or remotely sensed observations, with little or no ground truthing. The aim of this study was to assess the local perceptions of the distribution of socio-economically important tree species in the Sub-Sahel of Burkina Faso. Semi-structured interviews were performed with 87 groups of informants from 20 villages belonging to three ethnic groups (Mossi, Fulani and Samo). Univariate and multivariate statistics were used to compare perceptions between the targeted ethnic groups. According to the locals, more than 80 per cent of the 90 listed species were declining, with over 40 per cent identified as threatened, including numerous plants of great economic value. Increasing species were mostly drought-tolerant plants such as Balanites aegyptiaca. A few species were listed as locally extinct. Gender and age did not significantly affect local knowledge, whereas ethnicity did. The major causes of species decline were identified to be drought, deforestation and bushfires. In all ethnic groups, informants observed a southward shift in species distribution. Local perceptions suggest a general decline in woody vegetation. Thus, the alleged (re)greening in the Sahel might not have reversed the degradation of woody species in the area. Data derived from local ecological knowledge were consistent with that of many ecological studies, suggesting the reliability of people’s knowledge for obtaining ecological data. Information from this study can be used as baseline for conservation of species identified as threatened. Copyright © 2011 John Wiley & Sons, Ltd. key words: woody species; vegetation dynamics; Sub-Sahel; species shift; local ecological knowledge; ‘greening’; remote sensing; Sahelisation; ANOSIM INTRODUCTION Because of severe droughts in the 1970s and 1980s, climatic and environmental change in the West African Sahel has attracted much scientific research (West et al., 2008). The last decade had been characterized by a controversial debate on the ‘(re)greening’ of the West African Sahel, which is described as a possible reverse of the process of deserti- fication in the area (Rasmussen et al., 2001; Olsson et al., 2005; Hein and De Ridder, 2006; Prince et al., 2007; Olsson and Hall-Beyer, 2008). Numerous studies, mostly based on remotely sensed data, have documented a recovery of the vegetation of the Sudano-Sahelian zone of Burkina Faso (Hountondji et al., 2006) and in other Sahelian areas in Africa (Anyamba and Tucker, 2005; Seaquist et al., 2008; Olsson et al., 2005; Hermann et al., 2005). The interpreta- tion of this (re)greening pattern has caused much contro- versy in the scientific community, which remains unsettled. Some scientists consider the re-greening as a recovery process of the vegetation from a long period of degradation, recovery that is thought to be correlated with an increase in rainfall (Rasmussen et al., 2001; Nicholson, 2005; Eklundh and Olsson, 2003). Another school of thought also acknowledged that rainfall played an important role, but considered changes in land use and land management practices in the Sahel to be the driving factors. Other important influences were identified as cultural issues, ownership of trees, forestry laws and economic opportunities (Reij et al., 2009). The latter observed that the (re)greening pattern was associated with a significant increase in tree abundance on private farms. However, investigations of local ethnobotanical knowledge coupled with botanical investigations consistently indicated a decline, not a recovery, of woody vegetation in the West African Sahel and in Burkina Faso, resulting from both natural and anthropogenic factors (Lykke et al., 1999; Wezel and Haidis, 2001; Müller and Wittig, 2002; Kristensen and Balslev, 2003; Lykke et al., 2004; Wezel and Lykke, 2006; Ayantunde et al., 2008; Paré et al., 2010; Sop et al., 2010). These contradictory results raised concern over the credibility and the real meaning of the alleged (re)greening pattern and its impact on species diversity and plant abundance on ground. In regards to *Correspondence to: Tene Kwetche Sop, Biodiversity, Evolution and Ecol- ogy of Plants, Biocentre Klein Flottbek and Botanical Garden, University of Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany. E-mail: tenesop@googlemail.com; tene.kwetche.sop@botanik.uni-hamburg.de Copyright © 2011 John Wiley & Sons, Ltd. land degradation & development Land Degrad. Develop. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ldr.1144