1 Definition, Geographical Limits, Contacts with Other Ecoclimatic Zones.- 2 Environmental Characteristics.- 2.1 Climatic Factors.- 2.2 Edaphic Factors.- 2.3 Anthropozoic Factors: Man and Land Use.- 2.4 Ecoclimatic Classification.- 3 Flora and Vegetation.- 3.1 Flora.- 3.2 Vegetation.- 4 Wildlife.- 4.1 General.- 4.2 Invertebrates.- 4.3 Vertebrates.- 4.4 Conclusions.- 5 Livestock.- 5.1 General.- 5.2 Livestock Numbers, Evolution of Numbers, Densities, Stocking Rates.- 5.3 Breeds.- 5.4 Herd and Flock Structure and Demography.- 5.5 Average Production Parameters.- 5.6 Productivity.- 5.7 Disease, Parasitism, Predation, Theft.- 5.8 Production Systems and Herd Management.- 5.9 Nutrition, Plant-Animal Relationships, Grazing Patterns, Grazing and Herding Management, Stock Behaviour, Stocking Rates and Carrying Capacities.- 6 Development Outlook; Constraints and Limits.- 6.1 Range Improvement and Development.- 6.2 Development Outlook.- 7 Monitoring: A Case Study, the Ferlo Region of Northern Senegal.- 7.1 Introduction.- 7.2 The Pilot Zone of the Ferlo.- 7.3 Monitoring.- 7.4 Conclusions on Monitoring.- 8 General Conclusions: Towards an Ecological Management of the Sahelian Ecosystems.- References.- Index of Scientific Names.- Animals.- Plants.