In an account of Forest Soils (Chap. 147, Encyclopedia of Soil Science by Ratan Lal, published by CRC Press in 2005)，Nicholas B. Comerford asked “Why study forest soils? If there is a subdiscipline called forest soils，why not study com or tomato soils?” He replied himself by saying that studying forest soil science is justified because “a long-lived forest cover imposes a unique set of characteristics in which it grows”. He further argued that “soil characteristics and processes important to the forest soil scientists are not of great concern to cropland soil scientists for whom the biological and economic time frames of food production are relatively short”. Forest soil characteristics are not only unique but their interpretations are also differ¬ent A dense and thick vegetative cover，a continuous forest floor, very deep root systems, long duration (centuries for natural forests; decades for man-made forests) of occupancy of site, and natural succession of vegetation and soil as a coupled system make forest soils a distinctly dif-ferent entity. For example, we do not get a good crop harvest from a poorly fertile soil unless we add adequate fertilizers to an agricultural soil, but very productive tropical rainforests often can occur in poorly fertile Oxisols and Ultisols. Consideration of both native soil fertility and nutrient recycling may better give a projection of the forest site quality and productivity.
Forests cover almost one-third land area of the world. Scientific investigations of forest soil properties have also been considerable in Europe, America, and the former USSR. But I could find only a few books on forest soils when I had to deliver lectures on the subject to my second semester B.Sc. (Hons.) students in the Institute of Forestry and Environmental Sciences as a guest faculty during 1990s. The following books were very good books of soil science for foresters: Forest Soils and Forest Growth, S. A. Wilde (1950) Chronica Botanica Co.; Forest Soils: Properties and Processes^ K. A. Araιsoπ (1977) University of Toronto Press; Properties and Management of Forest Soils, William L. Pritchett and Richard F. Fisher (1987) Academic Press (latter edition Ecology and Management of Forest Soils，Richard F. Fisher and Dan Bin¬kley 2000,3rd Edition, Wiley), but I felt the necessity of a good book on forest soil science that would meet the requirements of general soil, forest soil, and environmental scientists.
Several dozens of good books are available on agricultural soils probably because agri¬cultural soils are related to our food security, agricultural crop lands are intensively managed systems and farmers often find problems in their management. Now-a-days, forest planta¬tions, particularly those for biomass energy production, are also being intensively managed with weeding, thinning, irrigation, and fertilizer addition. Good management without being well acquainted with the resource base is not possible. Forests are also useful in the context of global climate change adaptation and mitigation. These views inspired me to write this book Forest Soils: Properties and Management suited to students of soil science, forestry, and environmental sciences, and professionals of related disciplines. It has ten chapters. Chapter 1 gives background information on pedology. It will familiarize readers，may be even non-soil people, with the origin and development of soils. Chapters 2,3 and 5 describe physical，chemi¬cal, and biological properties of forest soils and their impacts on forest vegetation. Chapter 4 narrates forest soil organic matter. Nutrient dynamics in forest ecosystems are explained and elaborated in Chap. 6. An account of soil classification systems of the world and a description of the types of soils in different forest types of the world are given in Chap. 7. Forest soil degra¬dation due to natural and human induced forest disturbances is discussed in Chap. 8. Chapter 9 presents the relationship between forest soil quality and climate change. Forest management and silvicultural treatments related to seedling development, site preparation, planting, tend¬ing, weeding, fertilization, and irrigation and their effects on soil and environment have been discussed in considerable details in Chap. 10.
For last 20 years, I taught forest soils to undergraduate students of Soil Science and For¬estry and Environmental Sciences. The general outline of the preset book has been tested on these students during this period. I am grateful to my students. Their reactions and responses inspired me to shape this book. I tried to incorporate recent information and I hope this book will be helpful to foresters, forest managers, environmental experts, and students.

1 Rocks, Minerals, and Soils 1

1.1 Rocks 1

      1.1.1 Igneous Rocks 1

      1.1.2 Sedimentaιy Rocks 2

      1.1.3 Metamorphic Rocks 2

1.2 Minerals 3

      1.2.1 Classification of Minerals 3

1.3 Weathering 6

      1.3.1 Physical Weathering 6

      1.3.2 Chemical Weathering 7

      1.3.3 Biochemical Weathering 7

      1.3.4 Weatherabilty of Minerals and Weathering Products 7

1.4 Soils 8

      1.4.1 Pedoπ 8

      1.4.2 Soil Profile 8

1.5 Soil Formation 9

      1.5.1 Soil-Forming Factors 9

      1.5.2 Soil-Forming Processes 14

Study Questions 16

References

2 Physical Properties of Forest Soils 19

2.1 Soil Particles !9

2.2 Soil Texture 20

      2.2.1 Suitable Forest Tree Species for Different Soil Textures 20

      2.2.2 Soil Texture and Species Distribution 22

2.3 Soil Structure 22

      2.3.1 Soil Structure Formation 23

      2.3.2 Soil Structure and Tree Growth 24

2.4 Density, Porosity, and Compaction 24

      2.4.1 Effect of Soil Compaction on Forest Tree Growth 26

2.5 Soil Air 26

      2.5.1 Aeration 27

      2.5.2 Effect of Soil Air on Forest Tree Growth 27

2.6 Soil Temperature 27

      2.6.1 Factors Affecting Forest Soil Temperature 27

      2.6.2 Effect of Soil Temperature on Forest Tree Growth and Physiology 29

      2.6.3 Effect of Soil Temperature on Forest Soil Processes 30

      2.6.4 Control of Forest Soil Temperature 31

2.7 Hydrological Properties of Forest Soils 31

      2.7.1 Hydrologic Cycle 31

      2.7.2 Effect of Water Stress on Forest Trees 35

      2.7.3 Effect of Waterlogging on Forest Trees 35

2.8 Soil Water 36

Study Questions 38

References 38

3 Chemical Properties of Forest Soils 45

3.1 Chemical Composition of Soils 45

3.2 Soil Solution 45

3.3 Soil Reaction 47

3.4 Liming 50

3.5 Buffering Capacity 50

3.6 Ion Exchange 51

3.7 Base Saturation Percentage 52

3.8 Salinity and Sodicity 53

3.9 Free Carbonates 56

3.10 Redox Potential (Eh) 57

Study Questions 58

References 58

4 Organic Matter of Forest Soils 63

4.1 Soil Organic Matter 63

4.2 Sources of Organic Matter in Forest Soil 63

4.3 Categories of SOM 64

4.4 Functions of Organic Matter in Forest Soil 64

4.5 Forest Floor 66

4.6 Chemical Composition of SOM 67

4.7 Dissolved Organic Matter in Forest Soil 69

4.8 Types of Humus in Forest Soils 71

4.9 Organic Matter Content in Forest Soils 72

4.10 SOM Turnover 73

Study Questions 74

References 74

5 Biological Properties of Forest Soils 77

5.1 Forest Soil Organisms 77

5.2 Plant Roots 78

5.3 Mycorrhizae 79

5.4 Soil Microflora 79

      5.4.1 Functions of Microflora in Forest Soil 80

5.5 Soil Fauna 83

      5.5.1 Macrofauna in Soils of Different Types of Forests 91

      5.5.2 Functions of Macrofauna 91

Study Questions 92

References 92

6 Nutrient Dynamics in Forest Soil 97

6.1 Biomass and Nutrients 97

      6.1.1 Biomass Production 97

6.2 Nutrient Retranslocation 101

6.3 Nutrient Recycling 102

      6.3.1 Nutrient Uptake 102

      6.3.2 Nutrient Retention 103

      6.3.3 Nutrient Return 103

      6.3.4 Nutrient Release 110

6.4 Forest Floor Biomass and Nutrients 114

Study Questions 115

References 115

7 Forest Types and Their Associated Soils 123

7.1 Forest Types of the World 123

      7.1.1 Tropical Forests 124

      7.1.2 Temperate Forests 128

      7.1.3 Boreal Forests 131

      7.1.4 Regional distribution of forests 133

7.2 General characteristics of forest soils 133

      7.2.1 Limitations of forest soils 134

      7.2.2 Natural Succession 134

      7.2.3 Forest Floor 135

7.3 Modem Soil Classification Systems 135

      7.3.1 Soil Taxonomy 135

      7.3.2 WRB for Soil Resources 139

7.4 Soils of Major Forest Types of the World 141

      7.4.1 Soils of Tropical Rainforests, Evergreen Forests and Deciduous Forests 141

      7.4.2 Soils of Tropical Montane Forests 145

      7.4.3 Soils of Tropical Freshwater Swamp Forests 147

      7.4.4 Soils of Tropical Mangrove Forests 147

      7.4.5 Soils of Tropical Miscellaneous Forests 148

      7.4.6 Soils of Temperate Forests 149

      7.4.7 Soils of Boreal Forest. 150

Study Questions 151

References 152

8 Forest Disturbances and Soil Degradation 157

8.1 Forest Disturbances 157

      8.1.1 Forest Harvest 159

      8.1.2 Fuel Biomass Collection 160

      8.1.3 Shifting Cultivation 160

      8.1.4 Forest Fires 162

      8.1.5 Deforestation 164

Study Questions 167

References 167

9 Forest Soil and Climate Change 173

9.1 Climate Change and Forests 173

9.2 Climate Change and Soil 175

9.3 Carbon Stock in Forest Soils 177

9.4 Temperature and Soil Organic Carbon 177

9.5 GHG Emissions from Forest Soils 178

9.6 Forestry Activities to Adapt to and Mitigate Climate Change 179

      9.6.1 Planting Forests 179

      9.6.2 Protecting Existing Forests 179

      9.6.3 Improved Forestry Techniques to Reduce Emissions 179

      9.6.4 Replacing High-energy Materials with Climate-friendly Substitutes 179

      9.6.5 Fossil Fuel Substitution Through Renewable Wood Energy 180

Study Questions 180

References 180

10 Forest Soil Management and Silvicultural Treatments 183

10.1 Objectives of Forest Soil Management 183

10.2 Soil Management-Related Terminologies 183

      10.2.1 Land Capability 183

      10.2.2 Soil Quality : 184

      10.2.3 Soil Productivity 185

      10.2.4 Site Quality and Site index 186

      10.2.5 Soil-site Evaluation 186

10.3 Forest Management 187

      10.3.1 Management of Natural Forests 187

10.4 Forest Plantations.. 188

      10.4.1 Major Plantation Tree Species 188

      10.4.2 Plantation Development 192

10.5 Effects of Forest Plantations on Soil 202

Study Questions 203

References 203

Index 211

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