Covering an area of over 130 million km2 spanning the Mediterranean, equator and tropics, the African continent features a spectacular geographic diversity. Consequently, it is characterised by extremely variable climatic, edaphic and ecological conditions, associated with a wide range of natural vegetation and wildlife, as well as human population density, crops and livestock. In this book, Henry Le Houérou presents his bioclimatic and biogeographic classification of Africa. The extensive data provide the basis for comparisons between various African regions, and with regions on other continents such as Latin America or the Indian subcontinent. The results constitute a rational basis for national, regional and sub-regional rural development planning, and for agricultural research dealing with aspects such as plant and animal introductions, the extrapolation or interpolation of experimental or developmental findings, and ecosystems dynamics. Possible problems of applications are also examined.

Contents 1 Introduction 1.1 Scope 1.2 Basic Concepts 1.2.1 General 1.2.2 Energy Flow and Budget 1.2.3 Drought 1.2.4 Cold Stress: Relation to Latitude and Elevation 1.2.5 Frost Hazard Occurrence in Africa (explanatory notes) 1.3 Classification Criteria 1.3.1 Latitude 1.3.2 Rainfall 1.3.2.1 Annual Amount 1.3.2.2 Seasonal Patterns 1.3.2.3 Length of Rainy Season 1.3.2.4 Variability and Dependability of Annual Rainfall 1.3.2.5 Rainfall Gradients 1.3.2.6 Evolution of Annual Rainfall, Causes of the Sahel Drought 1.3.2.7 Other Geographic Factors Affecting Rainfall: the Role of Oceanic Currents 1.3.2.8 Occult Precipitation 1.3.3 Potential Evapotranspiration (PET) 1.3.4 The P/PETp and P/ETo Ratios 1.3.5 Temperature 1.3.6 Relationship Between Mean Annual Temperature and Mean Annual ETo in 21 Countries in Africa 1.3.7 Other Significant Weather Parameters 1.3.7.1 Vapour Pressure, Relative Humidity, Saturation Deficit 1.3.8 Soil Distribution Climatic Aridity and Edaphic Aridity, Rain-Use Efficiency (RUE) 1.3.9 Impact of Agro-hydraulic Works 1.3.10 Land-Use Patterns, Agricultural Systems and Crop Distribution 1.3.10.1 General 1.3.10.2 The Hyper-arid Agro-bioclimatic Zone 1.3.10.3 The Arid Agro-bioclimatic Zone 1.3.10.4 The Semi-arid Agro-bioclimatic Zone 1.3.10.5 The Sub-humid Agro-bioclimatic Zone 1.3.10.6 The Humid Agro-bioclimatic Zone 1.3.10.7 The Hyper-humid Agro-bioclimatic Zone 1.3.11 Rangelands, Pasture Production and Yields 1.3.12 Native Flora 1.3.13 Vegetation 1.3.14 Livestock Species and Breeds 1.3.15 Wildlife 1.3.16 Human and Animal Diseases and Parasites 1.3.17 Human Comfort 2 Bioclimatic Classification 2.1 General 2.2 Extra-tropical African Bioclimates, Particularly Mediterranean 2.2.1 Mediterranean Bioclimates (Weakly Bimodal Rainfall Regime, in Africa) 2.2.2 The Sahara 2.2.3 The Subtropical Bioclimates of South Africa 2.3 Inter-tropical Bioclimates 2.3.1 Tropical Agro-bioclimates 2.3.2 The Southern African Miombo Savanna and Woodland Zone 2.3.3 The Equatorial Agro-bioclimates 2.3.4 Overall Classification Sketch 2.4 Relations to Other Classifications 3 Land Degradation, Desertization and Rehabilitation 3.1 Causes of Land Degradation 3.2 Land Desertization 3.3 Land Rehabilitation 4 Conclusions Appendix Bibliography