This book provides a quantitative analysis of the role of woody plants in semi-arid regions, for the aSSessment of their benefits in agrosylvopastoralland-use systems with productive and sus tainability objectives. The insights presented and conclusions drawn allow the additional benefits of woody plants for specific climatic and physical site conditions and land-use systems to be estimated. The Sahel and Sudan zones in West Africa, on which the book focusses, represent resource-poor conditions, whose ecological dynamics have been relatively well studied. The role of woody plants in this region, as assessed in this book, is extrapolated to other semi-arid regions, leading to general conclusions on agroforestry's potential as an option for sustainable land use in semi-arid regions. The origins of this book go back to 1982, when the Club du Sahel requested that available data on woody plants in the Sahel region be synthesised, to provide basic information to enable better attention to be given to woody plants in rural development programmes. We are grateful to the Club du Sahel for this challenge. Various people contributed to studies used in this book. The preliminary inventory of the data available was made by Frits Ohler; later his work was continued by Franciska Dekker.

Inhalt
1 Introduction.- 2 The Distribution and Canopy Cover of Woody Species.- 2.1 Introduction and Methodology.- 2.2 Distribution and Canopy Cover Data.- 2.3 An Ecological Interpretation of Woody Vegetation in the SSWA.- 2.4 Human Influences on Woody Plants.- 2.5 Conclusions.- 3 Production of Woody Plants.- 3.1 Introduction.- 3.2 Productivity and Biomass of Woody Plant Communities.- 3.3 Production of Woody Plant Components.- 3.4 Estimating Woody Plant Production.- 3.5 Phenology.- 3.6 Nutrient Concentrations, Digestibility and Palatability.- 4 The Influence of Woody Plants on Plant Production Factors.- 4.1 Introduction.- 4.2 Interactions Between the Woody and Herbaceous Layer.- 4.3 Root Systems of Woody Plants.- 4.4 Influences of Woody Plants on Water Availability.- 4.5 Influences of Woody Plants on Nutrient Availability.- 4.6 Soil Organic Matter and its Functions in Relation to Woody Plants.- 4.7 Influences of Woody Plants on Light Availability.- 4.8 Potential Influences of Woody Plants on Plant Production.- 5 Synthesis, Generalisation and Recommendations.- 5.1 Introduction.- 5.2 Woody Plants and Plant Production Factors.- 5.3 Productive Benefits by Woody Plants.- 5.4 The Role of Woody Plants in Land-Use-Systems.- References.