The seventh edition of this classic student text explores the multitude of impacts that humans have had over time upon vegetation, animals, soils, water, landforms and the atmosphere. It also looks into the future and considers the ways in which climate changes and modifications in land cover may change the environment in coming decades. Extensively re-written, it contains many new statistical tables, figures, and references. It is essential reading for undergraduates in geography and environmental science, and for those who want a thorough, wide-ranging and balanced overview of the impacts of humans upon natural processes and systems from the Stone Age to the Anthropocene and who wish to understand the major environmental issues that concern the human race at the present time.

InhaltsangabePREFACE TO THE SEVENTH EDITION xi ABOUT THE COMPANION WEBSITE xii PART I: THE PAST AND PRESENT 1 1 INTRODUCTION 3 Chapter Overview 3 The development of ideas 3 The development of human population and stages of cultural development 7 Hunting and gathering 11 Humans as cultivators, keepers and metal workers 13 Modern industrial and urban civilizations 20 Points for review 25 Guide to reading 25 2 THE HUMAN IMPACT ON VEGETATION 26 Chapter Overview 26 Introduction 26 The use of fire 27 Fires: natural and anthropogenic 29 Some consequences of fire suppression 30 Some effects of fire on vegetation 32 The role of grazing 32 Deforestation 34 Secondary rain forest 42 The human role in the creation and maintenance of savanna 43 The spread of desert vegetation on desert margins 46 The maquis of the mediterranean lands 51 The prairies and other mid-latitude and high-altitude grasslands 51 Postglacial vegetational change in Britain and Europe 53 Lowland heaths 55 Introduction, invasion and explosion 56 Air pollution and its effects on plants 61 Forest decline 63 Miscellaneous causes of plant decline 65 The change in genetic and species diversity 66 Conclusion: threats to plant life 67 Points for review 68 Guide to reading 69 3 HUMAN INFLUENCE ON ANIMALS 70 Chapter Overview 70 Domestication of animals 71 Dispersal and invasions of animals 71 Human influence on the expansion of animal populations 76 Causes of animal contractions and decline: pollution 80 Habitat change and animal decline 83 Other causes of animal decline 86 Animal extinctions in prehistoric times 90 Modernday extinctions 94 Points for review 101 Guide to reading 102 4 THE HUMAN IMPACT ON THE SOIL 103 Chapter Overview 103 Introduction 103 Salinity: natural sources 104 Human agency and increased salinity 105 Irrigation salinity 105 Dryland salinity 107 Urban salinity 108 Interbasin water transfers 108 Coastal zone salinity 109 Consequences of salinity 110 Reclamation of salt-affected lands 113 Lateritization 113 Accelerated podzolization and acidification 114 Some anthrosols resulting from agriculture and urbanization 115 Soil carbon 116 Soil structure alteration 116 Soil drainage and its impact 118 Soil fertilization 119 Fires and soil quality 120 Soil erosion: general considerations 120 Soil erosion associated with deforestation and agriculture 122 Accelerated wind erosion 126 Soil erosion produced by fi re 128 Soil erosion associated with construction and urbanization 129 Soil conservation 130 Points for review 133 Guide to reading 133 5 THE HUMAN IMPACT ON THE WATERS 134 Chapter Overview 134 Introduction 134 Deliberate modification of rivers 135 Urbanization and its effects on river flow 143 Vegetation modification and its effect on river flow 145 The human impact on lake levels 148 Changes in groundwater conditions 150 Water pollution 155 Chemical pollution by agriculture and other activities 157 Deforestation and its effects on water quality 162 Thermal pollution 164 Pollution with suspended sediments 165 Marine pollution 165 Points for review 168 Guide to reading 168 6 HUMAN AGENCY IN GEOMORPHOLOGY 169 Chapter Overview 169 Introduction 169 Landforms produced by excavation 171 Landforms produced by construction and dumping 173 Sediment transport by rivers 174 Accelerated sedimentation 179 Ground subsidence 184 Arroyo trenching, gullies and peat haggs 187 Accelerated weathering and the tufa decline 191 Accelerated mass movements 192 Deliberate modification of channels 195 Nondeliberate riverchannel changes 195 Reactivation and stabilization of sand dunes 201 Accelerated coastal erosion 203 Changing rates of salt marsh accretion 209 The human impact o

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