Desertification: Natural Background and Human Mismanagement

ISBN-13: 9783642861864 / Angielski / Miękka / 2012 / 314 str.

Monique Mainguet

Opis

After UNCED (United Conference on Environment and Development, Rio de Janeiro, July 1992), a second edition of Desertification was necessary. About 150 corrections, amendments and additions take scientific progress into account. The author also presents an updated chapter in which the results of UNCED are analyzed.
This book aims at an understanding of what is commonly called "desertification" - a term which is proposed to be replaced by "land degradation." Each level of technology, excessive or insufficient, creates its own mismanagement. This is reflected in an increase in land degradation and eventually a decrease in soil productivity. The benefit to the reader is an awareness of the ecozones and a global overview of the phenomena, mechanisms and existing solutions.

Spis treści

1. What is Desertification?: Definitions and Evolution of the Concept.- 1.1 Definitions of Desertification.- 1.2 The Evolution of the Concept of Desertification.- 1.2.1 The Age of Awareness.- 1.2.2 The Age of Wrong Perception or Misconception.- 1.2.3 The Age of Doubt.- 1.2.4 The Myth of the Encroaching Desert.- 1.2.5 The Dawning of the New Realism.- 1.3 General Conclusion, Chapter 1.- 2. “Desertification” or Land Degradation: Location and Dimension in Time, Vulnerabilitiy of Soil and Plants in Drylands.- 2.1 Introduction.- 2.2 Location of “Desertification” or Land Degradation, Threatened Areas and Drought-Prone Regions.- 2.3 Dryness Ratio and Drought.- 2.3.1 Dryness Ratio.- 2.3.2 Drought.- 2.3.2.1 Meteorological Drought.- 2.3.2.2 Hydrological Drought.- 2.3.2.3 Agricultural Drought.- 2.4 The Droughts of the 20th Century Throughout the World.- 2.5 The Vulnerability of Soils in Drylands.- 2.6 The Survival of Plants in Dry or Seasonally Dry Ecozones.- 2.7 General Conclusion, Chapter 2.- 3. Dimensions in Space of “Desertification” or Land Degradation: The Degree and Specificity in Each Continent.- 3.1 Introduction: Global Dimension in Space of “Desertification”.- 3.2 Sub-Saharan Africa: Traditional Extensive Agriculture, Unadapted High Technology, and Land Degradation.- 3.2.1 Droughts in the Sahel.- 3.2.1.1 Paleo-Droughts and Historical Droughts.- 3.2.1.2 20th Century Droughts.- 3.2.1.3 Drought and Shifting Isohyets in Eastern Mali. Where Are the Most Severe Effects of Drought?.- 3.2.2 The Bioclimatological Ecozones.- 3.2.3 Traditional Land Occupation. Potentialities and Agricultural Limits in High Climatic Risk Drylands.- 3.2.3.1 Hunting.- 3.2.3.2 Fishing.- 3.2.3.3 Domesticated Stock-Keeping.- 3.2.3.4 Agriculture in Sub-Saharan Drylands.- 3.2.4 What Are the Risks and How Can They Be Avoided?.- 3.2.4.1 In the Sahel.- 3.2.4.2 In the Sudanian Zone.- 3.2.4.3 The Sudano-Guinean Subzone.- 3.2.5 Environmental Difficulties of Development. Disasters: What Disasters?.- 3.2.5.1 Overgrazing.- 3.2.5.2 Overcropping and Deforestation.- 3.2.6 Conclusion.- 3.3 Egypt: An Example of the Misapplication of High Technology Leading to Man-Made “Desertification”.- 3.3.1 Causes of Land Degradation.- 3.3.2 Processes of Land Degradation.- 3.3.2.1 Water Table Rising.- 3.3.2.2 Absence of Nile Alluvium Resulting in Wind Erosion.- 3.3.2.3 Loss of Nutrients.- 3.3.3 Effects of Land Degradation.- 3.3.4 Conclusion.- 3.4 China: A Sophisticated Traditional Intensive Agriculture Beginning to Be Modified by High Technological Methods and “Desertification” or Land Degradation.- 3.4.1 Introduction: The Agricultural Origin of Land and Degradation in China.- 3.4.2 Classification of the Desertified Areas in China.- 3.4.2.1 Deserted Land and Desertified Land in the Arid Ecosystems.- 3.4.2.2 A Second Type of Desertified or Degraded Land in China in Semi-Arid and Dry Subhumid Steppes.- 3.4.3 The Major Indicators of Degradation.- 3.4.3.1 Changes in Topography.- 3.4.3.2 Changes in Composition of the Vegetative Cover.- 3.4.3.3 Changes in Texture of the Top Soil.- 3.4.4 Human Factors Leading to Environmental Change in Semi-Arid and Dry Subhumid Zones in China.- 3.4.4.1 Overcultivation and Degradation.- 3.4.4.2 Overgrazing and Degradation.- 3.4.4.3 Firewood Collection and Degradation.- 3.4.4.4 Land Degradation by Misuse of Water Resources.- 3.4.4.5 Land Deterioration and Nonrural Human Activities.- 3.4.5 Conclusion.- 3.5 Transition from Traditional Low Technological to High Industrial Agriculture and Land Degradation in the Former USSR.- 3.5.1 Dry Ecozones in the Former USSR.- 3..5.2 Aridity and Other Physical Factors Leading to Land Degradation.- 3.5.2.1 The Climatic Factors.- 3.5.2.2 Soils.- 3.5.2.3 The Vegetation Resources.- 3.5.2.4 Water Resources.- 3.5.3 Human Activities and Land Degradation.- 3.5.3.1 Old Oases.- 3.5.3.2 Land Degradation in Desert Rangelands.- 3.5.3.3 Ecological Implication of Irrigation in Drylands.- 3.5.3.4 Environmental Impact of Industrial Development in Dryland of the Former USSR.- 3.5.4 Aeolian Action and Land Degradation in the Sandy Deserts of the Former USSR.- 3.5.5 Conclusion.- 3.6 High Technological Capital-Intensive Pastoralism and Land Degradation or “Desertification” in a Dry Continent: Australia.- 3.6.1 Human Causes of Land Degradation in Arid Australia.- 3.6.2 Grazing and Other Agricultural Activities in Semi-Arid Australia.- 3.6.3 Land Degradation in Irrigated Areas.- 3.6.4 Land Degradation in Nonagricultural Areas.- 3.6.4.1 Impact of Urban Settlements.- 3.6.4.2 Impact of Mining.- 3.6.5 Conclusion.- 3.7 High Technological Capital-Intensive Agriculture and Soil Degradation or “Desertification” in North America.- 3.7.1 Location of Land Degradation in the Drylands of the USA.- 3.7.2 The Causes of Land Degradation.- 3.7.2.1 Excessive Water Consumption: First Cause of Land Degradation.- 3.7.2.2 Overgrazing: Second Cause of Land Degradation.- 3.7.2.3 Salinization: Third Cause of Land Degradation.- 3.7.2.4 Physical Soil Erosion: Fourth Cause of Land Degradation.- 3.7.2.5 Combined Causes and Mechanisms of Land Degradation.- 3.7.3 Conclusion.- 3.8 General Conclusion, Chapter 3.- 4. Processes Leading to Soil Degradation and “Desertification”.- 4.1 Introduction.- 4.2 Physicochemical Processes of Degradation.- 4.2.1 Potential Modifications and Decay of Soil Structure.- 4.2.2 Leaching.- 4.2.2.1 Aspects of Degradation by Leaching in the Upper Horizons of the Soil.- 4.2.2.2 Aspects of Degradation by Leaching in the Lower Horizons of the Soil.- 4.2.3 Waterlogging.- 4.2.4 Salinization and Alkalinization.- 4.2.4.1 Processes.- 4.2.4.2 Case Studies of Salinization: An Age-Old Irrigation Problem.- 4.2.5 Conclusion.- 4.3 Physical Processes of Land Degradation: Water Erosion.- 4.3.1 Soil Loss.- 4.3.2 Deteriorating Mechanisms of Water Action.- 4.3.3 Raindrop and Splash Effect.- 4.3.4 Runoff Action.- 4.3.5 Conclusion.- 4.4 Physical Processes of Land Degradation: Wind Erosion; Where Is the Danger?.- 4.4.1 What is Wind?.- 4.4.2 The Influence of Topography on Wind Conditions.- 4.4.3 The Wind Action Sytem.- 4.4.3.1 Source Area.- 4.4.3.2 Transport Area.- 4.4.3.3 Deposit Area and Dune Formation.- 4.4.4 The Effects of Wind on Vegetation.- 4.4.5 Aeolian Soil Erosion.- 4.5 General Conclusion, Chapter 4.- 5. Prevention and Remendies.- 5.1 Introduction.- 5.2 Possibilities for Overcoming Climatic Risks in Drylands.- 5.2.1 Cloud Seeding an Weather Modifications.- 5.2.2 Strengthening of Meteorological Services.- 5.3 Avoiding the Threat to Vegetation.- 5.3.1 Vulnerability of Dryland Vegetation.- 5.3.2 How to Obtain Biological Recovery.- 5.3.2.1 Natural Recovery.- 5.3.2.2 Artificial Recovery.- 5.3.3 Solutions to Avoid Grazing Effects.- 5.3.3.1 Carrying Capacity.- 5.3.3.2 Mobile Resources for Nomadic Pastoralism.- 5.3.3.3 Game Ranching Instead of Cattle.- 5.3.3.4 Fodder Harvesting.- 5.4 Some Solutions to Improve Drylands Agriculture.- 5.4.1 Drought-Adapted Plants.- 5.4.2 Introduction of Lesser-Known Plants.- 5.4.3 Reclaiming Salty Soils and Water.- 5.4.4 Plant Breeding.- 5.5 More Integrated Rural Activities for Agriculture Amelioration.- 5.5.1 Multicrop Agriculture.- 5.5.2 Natural Bushland Exploitation.- 5.5.3 Soil Degradation and Rehabilitation of an Agropastoral Land in Tanzania. Hopeful “De-Desertification”: Case Study.- 5.5.3.1 Degradation.- 5.5.3.2 Results of the HADO Projekt “De-Desertification” in Tanzania.- 5.6 Water Conservation Measures.- 5.6.1 Introduction.- 5.6.2 Difficulties in Obtaining Water.- 5.6.2.1 High Technology Solutions: A Mitigated Success.- 5.6.2.2 Low Technology Irrigation Systems and Water Conservation Measures.- 5.6.2.3 The Basic Requirements of Irrigation.- 5.6.2.4 Deep Borewells.- 5.6.3 Water Harvesting.- 5.6.4 Desalinization Techniques in the Search for Freshwater.- 5.6.5 Conclusions.- 5.7 Maintaining Soil Quality.- 5.7.1 Introduction.- 5.7.2 Halting Water Erosion.- 5.7.2.1 Control of Sheet-Wash and Rillwash.- 5.7.2.2 Gully Reclamation.- 5.7.3 Control of Damaging Wind Effects.- 5.7.3.1 Methods for Preventing Progression of the Barchans.- 5.7.3.2 Control of Seif Dunes.- 5.7.3.3 Strategies for the Control and Prevention of Sand Encroachment.- 5.7.3.4 Windbreaks, Shelterbelts, and Wind Barriers.- 5.7.3.5 Additional Methods of Controlling the Wind.- 5.8 Training and Research.- 5.8.1 Training.- 5.8.1.1 What Is Not Working?.- 5.8.1.2 What Can Tradition Bring?.- 5.8.2 Research Results.- 5.9 General Conclusion, Chapter 5.- 5.9.1 The Specific Solutions for China.- 5.9.2 Africa Must Find its Own Specific Remedies.- 6. General Conclusion: The Need for a New Realism.- 7. New Developments in Desertification (September 1993).- 7.1 Natural Causes: Droughts Since the Beginning of the Century.- 7.2 Human Causes.- References.- Author Index.- Subject hidex.