Modeling Soil and Woody Vegetation in the Senegalese Sahel in the Context of Environmental Change

Martin Brandt, Tobias Grau, Cheikh Mbow and Cyrus Samimi
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Martin Brandt: Institute of Geography, University of Bayreuth, 95440 Bayreuth, Germany
Tobias Grau: Institute of Geography and Regional Research, University of Vienna, 1090 Vienna, Austria
Cheikh Mbow: Forestry-ICRAF (World Agroforestry Center), 00100 Nairobi, Kenya
Cyrus Samimi: Institute of Geography, University of Bayreuth, 95440 Bayreuth, Germany

Land, 2014, vol. 3, issue 3, 1-23

Abstract: Climatic stress and anthropogenic disturbances have caused significant environmental changes in the Sahel. In this context, the importance of soil is often underrepresented. Thus, we analyze and discuss the interdependency of soil and vegetation by classifying soil types and its woody cover for a region in the Senegalese Ferlo. Clustering of 28 soil parameters led to four soil types which correspond with local Wolof denotations: Dek, Bowel, Dior and Bardial. The soil types were confirmed by a Non-metric Multidimensional-Scaling (NMDS) ordination and extrapolated via a Random Forest classifier using six significant variables derived from Landsat imagery and a digital elevation model (out-of-bag error rate: 7.3%). In addition, canopy cover was modeled using Landsat and a Reduced-Major-Axis (RMA) regression (R 2 = 0.81). A woody vegetation survey showed that every soil type has its own species composition. However, 29% of Bowel regions are deforested (i.e., degraded) and interviews revealed extensive environmental changes and a strong decline and local extinction of woody species. The differences between the soil types are significant, showing that vegetation changes (i.e., degradation and greening), resilience to climatic stress and human activities largely depend on soil properties. We highlight that spatial heterogeneity is an important aspect when dealing with environmental changes in the Sahel, and local knowledge can be well used to classify spatial units by means of public Earth observation data.

Keywords: Sahel; degradation; environmental change; soil; NMDS; Random Forest; Senegal; Wolof; canopy cover; Ferlo (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2014
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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