Soil Erosion Control in Drylands

Preface
Contents
1 Soil Erosion: Factors, Processes and Effects
	1.1 Introduction
	1.2 Overview of the Effects of Soil Erosion
		1.2.1 The Effects in the Eroded Area (Intra-Regional)
		1.2.2 The Effects of Sediments in the Transport and Sedimentation Area (Extra-Regional)
		1.2.3 Effect of Soil Erosion on Greenhouse Gases
		1.2.4 Economic Losses of Soil Erosion
	1.3 Soil Erosion: Factors and Processes
	1.4 Effective Factors in Soil Erosion
		1.4.1 The Effect of Climate on Soil Erosion
		1.4.2 The Effect of Land Use and Vegetation on Soil Erosion
		1.4.3 The Effect of Topography on Soil Erosion
		1.4.4 The Effect of Soil Properties on Soil Erosion
		1.4.5 The Effect of Human Activities on Soil Erosion
	1.5 Intra-Regional Effects of Soil Erosion
		1.5.1 Erosion and Soil Quality
	1.6 Extra-Regional Effects of Soil Erosion
		1.6.1 Intra-Regional Control of Non-point Pollutants
	1.7 Global Effects of Soil Erosion
		1.7.1 Soil Carbon Storage and Its Changes
		1.7.2 Soil Erosion and Carbon Fluctuations
		1.7.3 Study of Soil Carbon Loss at Different Scales
		1.7.4 Soil Carbon Sequestration and Protection
	1.8 Economic Effects of Soil Erosion
	References
2 The Role of Vegetation in Confronting Erosion and Degradation of Soil and Land
	2.1 Introduction
	2.2 Definition of Bioengineering
	2.3 History
	2.4 Literature Review of Research Conducted
	2.5 Concepts and Terms
		2.5.1 Soil Cohesion
		2.5.2 Internal Friction Angle
		2.5.3 Stress
		2.5.4 Shear Stress
		2.5.5 Shear Strength
		2.5.6 Normal Stress
		2.5.7 Soil Shear Strength
		2.5.8 Slope Safety or Stability Factors
		2.5.9 Analysis of Slope Stability
	2.6 Methods for Measuring Soil Shear Strength (Without Root)
		2.6.1 Direct Shear Box Test
		2.6.2 Methods for Measuring the Shear Strength of Soil Containing Plants Roots
	2.7 Effect of Vegetation on Slope Stability
		2.7.1 Effect of Vegetation on Prevention and Control of Surface Erosion
		2.7.2 Effect of Plants on Prevention and Control of Streambank Erosion
		2.7.3 Effect of Vegetation on Prevention and Control of Soil and Land Mass Movements
		2.7.4 Effect of Vegetation on Slope Stability
		2.7.5 Effect of Plants Roots on Slope Stability
		2.7.6 Effect of Branches and Leaves on Slope Stability
		2.7.7 Negative Effects of Vegetation Cover on Steep Slope Stability
	2.8 Effect of Plants Vegetative Form on Erosion Prevention and Control
	2.9 Effect of Woody Vegetation on Soil Mass Stability
	2.10 Range of Plant Root Effect on Soil Mass Stabilization
		2.10.1 The Main Roots and Their Depth of Penetration into the Soil
		2.10.2 Effect of Tensile Strands and Plant Roots on Shear Strength of Soil
		2.10.3 Infinite Slope Analysis
		2.10.4 Effect of Root Mechanical and Compressive Force on Slope Stability
	2.11 Effect of Plant Species and Management of Vegetation Restoration Projects on Slope Stability
		2.11.1 Plant Successional Changes
		2.11.2 Functional Roles of Vegetation in Combating and Controlling Erosion
	2.12 Evaluation of Habitat
		2.12.1 Landscape
		2.12.2 Protection Designs
		2.12.3 Vegetation of Surrounding Lands
		2.12.4 Drainage Properties
		2.12.5 Soil Structure and Fertility
		2.12.6 Seed Quantity and Composition
		2.12.7 Landscape Design
	2.13 Selection of Plant Species
		2.13.1 Selection Methods
		2.13.2 Performing Tests
		2.13.3 Cultivation Methods
		2.13.4 Management and Monitoring
	2.14 Root Growth and Moisture Needed for Trees and Other Vegetative Types
		2.14.1 Root Growth
		2.14.2 Moisture Movement in Soil
		2.14.3 Surface Maintenance on Soil
		2.14.4 Relative Amount of Precipitation Received
	2.15 Methods of Plant Vegetation Establishment on Steep Slopes
		2.15.1 Root Properties in Slope Stabilization Design
		2.15.2 General Principles of Slope Stability
		2.15.3 Application of Robinia Pseudoacacia to Stabilize Slopes
		2.15.4 Root Properties
	2.16 Further Developments in Engineering and Stabilization of Slopes with Vegetation
		2.16.1 Advances in Eco-Engineering
		2.16.2 Signs of the Past
		2.16.3 Regions
		2.16.4 Tropical Regions
		2.16.5 Organizational Aspects
		2.16.6 Organizing Eco-Engineering Projects
		2.16.7 Insurance by Multilateral Foundations and NGOs
		2.16.8 Future-Design
		2.16.9 Methods
		2.16.10 Aspects of Project Management and Contracting in the Future
		2.16.11 Research
		2.16.12 Computer Modeling
		2.16.13 Further Effects and Future Objectives Trend
		2.16.14 Eco-Engineering Environmental Classification and Database
		2.16.15 Marginal Discoveries and Innovations
		2.16.16 Costs
		2.16.17 Summary
	2.17 The Role of Plants in Refining Soil Contamination
		2.17.1 Definition of Phytoremediation of Soil
		2.17.2 History of Phytoremediation
		2.17.3 Advantages and Disadvantages of Phytoremediation
		2.17.4 Contamination Refining Methods
		2.17.5 Plant Mechanisms for Soil Detoxification
		2.17.6 The Role of Root Secretion in Soil Detoxification
		2.17.7 Modification Materials and Increased Absorption Efficiency of Heavy Metals in the Plant
		2.17.8 Phytoremediation Methods
		2.17.9 Mechanism of Organic Remedies Solubility in Phytoabsorption
		2.17.10 Application of Mineral Agents to Increase Phytoabsorption
		2.17.11 Types of Contamination
		2.17.12 Phytoremediation of Petroleum Contaminants
		2.17.13 Decomposition of Petroleum Contaminants
		2.17.14 Effect of Plant Root Exudate on Soil Refining
		2.17.15 Plant Roles in the Bioavailability of Petroleum Contaminants
		2.17.16 Plant Roles in Increasing the Genes Affecting Contaminant Degradation
	2.18 Examples of Species Studied for Phytoremediation
	2.19 Water Harvesting in Arid Lands
		2.19.1 Introduction
		2.19.2 Rainwater Harvesting Techniques
		2.19.3 Choosing the Method for Water Harvesting
	References
3 Biological Control of Water Erosion
	3.1 Management Measures and Biomechanical Operations in Watershed
		3.1.1 Biological Methods of Preventing and Combating Soil Erosion
		3.1.2 Management Measures
		3.1.3 Plowing Modification
		3.1.4 Protection and Exclusion
		3.1.5 Exclusion Objectives
		3.1.6 Land Use Improvement
		3.1.7 Preserving Vegetation and Soil Humus
	3.2 Biological Operations
		3.2.1 The Reasons of Superiority for Biological Control of Soil Erosion Rather Than Mechanical (Structural) Methods
		3.2.2 Selection of Suitable Plants for Soil Conservation
		3.2.3 Plant Resistance to Pests and Diseases
	3.3 Biological Operations
		3.3.1 Rangeland Management
		3.3.2 Selection of Proper Species for Rangeland Management
		3.3.3 Properly Preparation of the Soil and Seed Bed
		3.3.4 Seeding
		3.3.5 Seeding and Its Different Types
		3.3.6 Interseeding
		3.3.7 Cultivation of Rangeland and Forage Plants and Creating Pasture
		3.3.8 Crop Rotation
		3.3.9 Rainfed Agriculture
		3.3.10 Raun Kaier’s Method
		3.3.11 Classification of Pabot
		3.3.12 Classification Based on the Precipitation Amount
		3.3.13 Other Classification Methods
		3.3.14 Plant Species Suitable for Different Vegetation Zones in Iran
		3.3.15 Shrub Planting
		3.3.16 Mount Culture
		3.3.17 Breeding and Preparation of Seedlings
		3.3.18 Increased Soil Moisture Storage for Planting Seedlings
		3.3.19 Evaporation Control
		3.3.20 Cuttings, Stool Shoots and Root Suckers
		3.3.21 Fertilizing Rangeland
		3.3.22 Stabilization of Sloping Lands by Plants
		3.3.23 Buffer Protection Areas
	3.4 Suitable Plants for Biological Control of Soil Erosion and Vegetation Restoration in Semi-arid Regions
		3.4.1 The Issues of Semi-arid Regions
		3.4.2 Suitable Plants for Biological Control of Soil Erosion and Rangeland Restoration in Semi-arid Regions
		3.4.3 Suitable Plants for Semi-arid Regions with an Average Annual Rainfall of 300–350 mm
		3.4.4 Suitable Plants for Semi-arid Regions with Average Annual Rainfall of 350–500 mm
		3.4.5 Suitable Plants for Semi-arid Regions with an Average Annual Rainfall of More Than 500 mm
	3.5 Vegetative Mulching
	3.6 Biological Control of Gully Erosion
		3.6.1 Method to Control Gully Erosion
		3.6.2 Characteristics of Suitable Plants for Biological Control of Gully Erosion
		3.6.3 Important and Suitable Plants for Prevention, Control, and Combating Against Gully Erosion
	3.7 Biological Control of Tunnel Erosion (Dissolution Erosion)
		3.7.1 Appropriate Methods for Biological Control of Tunnel Erosion and Created Gullies
	3.8 Biological Control of Stream and River Erosions
		3.8.1 Causes of Destruction in Riversides
		3.8.2 The Methods of Biological Control of Lateral Erosion
	3.9 Protecting the Structure of Earthen Dam and Beaches of Seas and Lakes Using Plants
	References
4 Wind Erosion Biological Control
	4.1 Direct Control
	4.2 Indirect Control
	4.3 Methods for Preservation and Regeneration of Vegetation in Deserts
		4.3.1 Role of Proper Methods in Water Resources Exploitation and Irrigation for Regenerating Vegetation in Deserts
		4.3.2 Correct Irrigation Methods in Deserts
		4.3.3 Appropriate Agricultural Approaches for Maintaining and Regenerating of Deserts’ Vegetation
		4.3.4 Vegetation Management
	4.4 Seedling Planting in Arid and Desert Regions
		4.4.1 Seeding Planting Objectives
		4.4.2 The Effect of Seedling on Preventing Wind Erosion
		4.4.3 The Role of Seedling in Creating Desired Conditions for Strengthening Vegetation
		4.4.4 The Role of Seedling in Minimizing Wind Erosion
		4.4.5 The Role of Seedling in Forming Windbreaks
		4.4.6 Windbreak Types and Their Properties
		4.4.7 The Role of Seedling and Forestry in Production and Supply of Plant Fuels
		4.4.8 The Role of Seedling in Beautification of the Environment and Promenade
		4.4.9 Seeding Process
		4.4.10 Seedling Planting Practices
		4.4.11 Different Forms of Seedlings Planting in Sand Dunes
	4.5 Seeding in Arid and Desert Regions
		4.5.1 Seeding Objectives
		4.5.2 Seeding Costs
		4.5.3 Seed Identification
		4.5.4 Adapted Plant Species Suitable for Cultivation in Arid and Desert Regions
		4.5.5 Seed Consumption in Arid and Semi-arid Regions
		4.5.6 Effective Factors on Seeding
		4.5.7 Proper Seeding Time
		4.5.8 Proper Depth of Seeding
		4.5.9 Proper Land and Seed Bed Preparation in Arid and Desert Regions Correctly
		4.5.10 Suitable Regions for Seeding
		4.5.11 Seeding in Saline Lands
		4.5.12 Seeding Practices
		4.5.13 Transplanting
		4.5.14 How to Sow Seed in Desert Areas
		4.5.15 Types of Seed Sowing
		4.5.16 Piling
		4.5.17 Care and Irrigation of Seeding and Seed Sowing Regions in Arid and Desert Areas: Applicable Methods
	4.6 Mulch and Mulching in Arid and Desert Areas
	4.7 Plants in Deserts of Iran
	4.8 Coastal Sand Dune Stabilization Methods
		4.8.1 Planting Pot Seedlings
		4.8.2 Characteristics of Plants Suitable for Biological Soil Erosion Control in Drylands and Sand Dunes
		4.8.3 Characteristics of Some of the Most Important Plants Suitable for Biological Soil Erosion Control in Arid and Desert Areas
	References
5 Biological and Biomechanical Methods for Stream Stabilization
	5.1 Introduction
	5.2 Advantages of Biotechnical Methods
	5.3 Role of Plants in Riverside
	5.4 Role of Plants in Slope Stability of Stream Side
	5.5 Structural Bioengineering Methods in Vulnerable Areas
	5.6 Basic Requirements for Natural Slope Construction
		5.6.1 Analysis of Safety Measures and Preferred Solutions
	5.7 Methods of Stabilizing the Slope of Streams and Rivers Walls
	5.8 Slope of Landslides
	5.9 Gabion with Planting and Reproduction with Cuttings
	5.10 Sample Projects
	5.11 Criterion of Selecting Construction Methods Using Living Plant Materials
	5.12 Biomechanical Structures to Combat and Inhibit a Variety of Water Erosion in Drained Lands
	5.13 Transversal Constructions
	5.14 Longitudinal Constructions
		5.14.1 Groins
	5.15 Log Bush Barriers
	References
6 Slope Stabilization Methods Using Biological and Biomechanical Measures
	6.1 Introduction
	6.2 Some Presented Principles for Biological Control of Soil Erosion
	6.3 Plant Properties for Soil Conservation and Erosion Control
		6.3.1 Choosing Appropriate Plants for Soil Conservation
		6.3.2 Field Choose
		6.3.3 Field Preparation
		6.3.4 Rainfall Harvesting and Surface Runoff Control
		6.3.5 Temporary Stabilization of Plant Beds
		6.3.6 The Methods of Saplings Transplantation to Natural Fields
		6.3.7 Propagating
		6.3.8 The Method of Sapling Conservation
	6.4 The Stabilization of Steep Lands by Means of Plants
		6.4.1 Plant Root System and Evapotranspiration
		6.4.2 Evapotranspiration and Its Effects on Soil Moisture
		6.4.3 Plantation on Steep Slopes
	6.5 The Usage of Plants for Gully Erosion Control
		6.5.1 Gully Erosion Control with Permanent Exclosure
		6.5.2 The Characteristics of Appropriate Plants for Biological Gully Erosion Control
		6.5.3 Important and Appropriate Plants for Gully Erosion Control and Prevention
		6.5.4 Gully Erosion Control by Means of Biological Control Without Exclosure
	6.6 Tunnel Erosion Control
		6.6.1 Appropriate Biological Methods for Tunnel and Gully Erosion Control
	6.7 Bank Erosion Biological Control
		6.7.1 The Causes of Land Degradation in River Margin
		6.7.2 Bank Erosion Control
		6.7.3 Protective and Retaining Living Walls
		6.7.4 Living Protector on the Steep Surface of River Side
		6.7.5 Short Living Lateral Obstacles for Bank Erosion Control
		6.7.6 Propagating and Planting Rooted Saplings in Floodways or River Margins
		6.7.7 Making Use of Tree Trunks for Rivers Margin Land Conservation
		6.7.8 Wire Screen Dead Parapets and Plantation
		6.7.9 Meander Course Reformation
		6.7.10 Conservation of Body Structure of Soiled Dams and Sea and Lake Coasts
		6.7.11 Combating Intrusive Plants, Pruning Excess Plant Jumps in River Margins
	6.8 Appropriate Plants for Biological Control of Soil Erosion in Semi-arid Regions and Plant Cover Restoration
		6.8.1 Introducing Appropriate Plants for Regions Which Have 180–350 mm/year Rainfall
		6.8.2 Appropriate Plants for Regions with 350–500 mm Precipitation Per year
		6.8.3 Appropriate Plants for Regions with More Than 500 mm Rainfall
	6.9 Appropriate Plants for Biological Soil Erosion Control in Arid Regions and Plant Cover Revitalization
	6.10 Costal Dune Stabilization
	6.11 Sand Dune Stabilization
	6.12 Engineering and Mechanical Methods
	6.13 Chemical Methods
	6.14 Planting Potted Plants
	6.15 The Properties of Plants Appropriate for Plant Cover Rehabilitation in Arid Regions
		6.15.1 Appropriate Plants for Biological Soil Erosion Control
	6.16 Introducing Significant and Appropriate Plants for Soil Erosion Control and Plant Cover Rehabilitation in Arid Regions
	6.17 Ground Bioengineering Systems
		6.17.1 Function and Effects
		6.17.2 Biological Building Materials
		6.17.3 Species Selection
		6.17.4 Vegetation Systems and Plant Origin
		6.17.5 Plant Propagation
		6.17.6 Preliminary Works
		6.17.7 Selection of the Method and Type of Construction
		6.17.8 Construction Timing
		6.17.9 Limits of Application
		6.17.10 Construction Costs
	6.18 Revegetation of Slopes by Surface Protection with Living Material
		6.18.1 Bush Mattress Construction (Bush Matting Construction) Procedure
		6.18.2 Materials
		6.18.3 Ecological and Technical Effectiveness
		6.18.4 Sodding (Turfing)
		6.18.5 Dry Seeding
		6.18.6 Mulch Seeding
		6.18.7 The Schiechteln Method (Mulch Seeding with Long Fiber Material) Procedure
		6.18.8 Placing of Seed Mats
		6.18.9 Placing of Concrete Blocks with Seeds
	6.19 Methods for Stabilizing Sloping Lands Adjoining Urban and Suburban Areas with Arid and Semi-Arid Climates Using Biological and Biomechanical Measures
		6.19.1 Introducing Some Drought Tolerant Plant Species for Highway Margin Landscaping
		6.19.2 Plant Characteristics Suitable for Vegetation Reclamation in Arid and Desert Areas and Highway Margins
		6.19.3 Suitable Plant Species for Landscaping Highway Margin
	6.20 Slope Stabilization Methods Using Living Materials
		6.20.1 Wattle (Wicker) Fences
		6.20.2 Cordon Construction
		6.20.3 Bush Wattles or Slope Fascines
		6.20.4 Groove (Furrow) Construction
		6.20.5 Hedge Layer Construction Procedure
		6.20.6 Bush Layer Construction
		6.20.7 Hedge Bush Layer Construction
		6.20.8 Placing of Cuttings, Including Wall Joint Planting
	6.21 Slope Stabilization by the Combined Use of Living and Non-living Materials
		6.21.1 Crib Wall Construction with Branch Layering Wooden Crib Wall
		6.21.2 Metal Crib Walls Constructed from Prefabricated Elements
		6.21.3 Vegetated Stone Walls and Rock Piles (Without Mortar)
		6.21.4 Vegetated Hard Gabions
		6.21.5 Soft Gabions
		6.21.6 Live Slope Gratings
		6.21.7 Lattice Construction
		6.21.8 Vegetated Palisade and Pole Construction
		6.21.9 Living Branch Layering of Gullies
	6.22 Biotechnical Drainage Systems
		6.22.1 Drainage by Using Pumping Plant Species (Phreatophytes)
		6.22.2 Grassed Waterways
		6.22.3 Live Fascine Drains
		6.22.4 Gravel Drains
	6.23 The Use of Geotextiles
		6.23.1 The Role of Geotextiles in Water Erosion Control
		6.23.2 Effects of Geotextiles on Hydrology
		6.23.3 Effects of Geotextiles on Soil Strength
		6.23.4 The Role of Geotextiles in Wind Erosion Control
		6.23.5 The Role of Geotextiles in Vegetation Establishment
		6.23.6 Effects of Geotextiles on Microclimate
		6.23.7 Effects of Geotextiles on Soil Conditions for Vegetation Establishment and Growth
		6.23.8 Comparisons Between Mulches and Geotextiles
		6.23.9 Care and Maintenance of Bioengineering Structures
	6.24 Rangeland Soil Management
		6.24.1 The Effects of Grazing on Rangeland Soils
		6.24.2 The Effect of Plant Covers on Rangeland Soils
		6.24.3 Rangeland Soil Restoration
		6.24.4 Organic Material and Soil Fertility
		6.24.5 The Cycle of Plant and Soil Organic Materials in Agroforestry
		6.24.6 The Effects of Plant Cover on Slope Stability
	6.25 Agroforestry
		6.25.1 Different Kinds of Agroforestry Systems
		6.25.2 Trees and Water Cycle
		6.25.3 Agroforestry Systems for Water Management
		6.25.4 Agroforestry and Soil Conservation
		6.25.5 Using Agroforestry System by Making Use of Trees to Control Erosion and Reform Existing Condition
		6.25.6 Advantages of Agroforestry System
	References
7 Agroforestry and Its Role in Soil Erosion Biological Control
	7.1 Integrated Land Use (Agroforestry)
	7.2 The Concept of Agroforestry
	7.3 The History of Agroforestry and Its Current Situation in the World
	7.4 Agroforestry Situation in Iran
		7.4.1 Agroforestry Systems in Caspian Region
		7.4.2 Agroforestry Systems in the Arasbaran Region
		7.4.3 Agroforestry Systems in Zagros Region
		7.4.4 Agroforestry Systems in Irano–Turanian Region
		7.4.5 Agroforestry Systems in Gulf-Oman Region
	7.5 Benefits of Agroforestry
		7.5.1 Ecological Benefits
		7.5.2 Economic Benefits
		7.5.3 Social Benefits
	7.6 Restrictions of Agroforestry
		7.6.1 Environmental Perspective
		7.6.2 Socioeconomic Perspective
	7.7 Measures for Soil Modification in Agroforestry Operations
	7.8 Selection of Tree Species
		7.8.1 Suitable Tree Species for Wetlands
		7.8.2 Selection of the Crop
	7.9 Types of Agroforestry Systems
		7.9.1 Periodic Cultivation
		7.9.2 Tree Fallow
		7.9.3 Intermediation Cultivation (Cultivation of Non-crop Plants Among Crops)
		7.9.4 Tongya
		7.9.5 Trees in the Arable Lands
		7.9.6 Multilevel System
		7.9.7 Marginal Cultivations
		7.9.8 Trees as Buildings to Control Erosion
		7.9.9 Windbreak and Wildlife Shield
		7.9.10 Row Intermediation Cultivation
		7.9.11 Strips on the Contour Lines
		7.9.12 Trees in Rangeland
		7.9.13 Live Rows and Hedges
	7.10 Multipurpose Trees in Agroforestry
		7.10.1 Benefits of Multipurpose Trees
		7.10.2 Properties of Multipurpose Trees Suitable for Agroforestry
		7.10.3 Trees for Forage Production
		7.10.4 Nitrogen-Fixing Trees
		7.10.5 Suitable Trees for Fuel Wood Production
	7.11 General Principles for the Management of Multipurpose Trees
	7.12 Management of Agroforestry System
		7.12.1 Primary Distance of Trees
		7.12.2 Pruning Type and Time
		7.12.3 The Amount and Time of Pruning
	7.13 Interactions of Trees and Crops
		7.13.1 The Interaction Effects
		7.13.2 Benefits of Studying Tree-Crop Interactions
		7.13.3 Required Information to Collect from Tree-Crop Interactions
		7.13.4 The Obvious Effects of Stresses on the Plant
		7.13.5 Environmental Factors in Agroforestry
		7.13.6 The Role of Environment in Agroforestry Systems
		7.13.7 The Environment and Tree-Crop Interactions
		7.13.8 Physical Environmental Factors
	7.14 Aspects of Soil Productivity in Agroforestry
		7.14.1 Soil Improvement Mechanisms in Agroforestry
		7.14.2 Effects of Trees on the Site Soil
		7.14.3 Effects of Trees on Their Productivity Soil Conservation
		7.14.4 Physical Conditions of Soil
		7.14.5 Soil Conservation and Agroforestry
		7.14.6 Benefits of Agroforestry Systems
	7.15 The Role of Haloxylon in Agroforestry
		7.15.1 Botanical Specifications of Haloxylon
		7.15.2 Haloxylon Cultivation
		7.15.3 Site
		7.15.4 The Role of Haloxylon as Windbreak in Agroforestry
		7.15.5 The Methods of Haloxylon Cultivation
		7.15.6 Impacts of Haloxylon on Some Physical and Chemical Properties of Soil
		7.15.7 The Role of Haloxylon in the Integrated Management of Pests and Diseases
		7.15.8 The Socio-economic Impacts of Haloxylon
		7.15.9 Importance of Haloxylon in Soil Conservation
	References