Wood is the usual end product of a forestry operation. Because of its importance, numerous studies have been made relative to wood prop­ erties, the causes of wood variation, and how best to develop wood for desired products. There is voluminous literature related to these subjects, but it is neither well known nor appreciated by foresters because the publications are often not available or are not well understood by the forester or by those who use the wood. Frequently, the literature is confusing and contradictory, making it difficult for the nonspecialist to use what information is available. In order to produce and use wood efficiently, the variation pat­ terns within trees, among trees within species, and among species must be understood. This also requires some knowledge of the causes of variation and the effects of different wood properties upon utiliza­ tion. The information about variation patterns, their causes, and con­ trol and effect upon the product must be known by the tree grower, the tree breeder, and the tree harvester as well as by those who ultimately convert wood into a final, salable product.

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1 Wood Variation and Wood Properties.- 1.1 What Is Wood?.- 1.2 Kinds of Trees and the Wood Produced by Them.- 1.3 Important Wood Properties.- 1.4 Wood Specific Gravity (Wood Density).- 1.4.1 What Determines Wood Specific Gravity?.- 1.4.2 The Importance of Specific Gravity.- 1.5 Cell Length.- 1.6 Other Wood Characteristics.- 1.7 Cell Chemistry.- 1.8 Factors Controlling Wood Properties.- 1.8.1 The Change from Earlywood to Latewood.- 1.9 Different Woody Tissues.- 1.9.1 Reaction Wood.- 1.9.2 Juvenile Wood.- 1.10 Relationships Among Wood Properties.- 1.11 The Literature Related to Wood Variation.- 2 The Effect of Provenance Variation and Exotic Plantations on Wood Properties.- 2.1 The Effect of Differing Environments on Wood Properties.- 2.2 Provenance Variation in Wood from Natural Stands Within the Range of a Species.- 2.2.1 Examples of Provenance Variation in Wood Properties in Natural Stands.- 2.2.2 A Summary of Provenance Variability in Wood from Natural Stands.- 2.3 Wood Variation Related to Species and Provenance in Plantation-Grown Trees.- 2.3.1 Examples of the Effect of Provenance upon Wood Properties of Trees in Plantations.- 2.4 Wood Properties of Trees Grown as Exotics.- 2.4.1 General Considerations.- 2.4.2 Changes of Wood Properties in Exotics.- 2.4.3 Wood Properties of Exotic Conifers - General.- 2.4.3.1 The Tropical Pines - Pinus caribaea Example.- 2.4.3.2 Conifers from Temperate Regions.- 2.4.3.3 Summary - Wood Properties of Exotic Conifers.- 2.4.4 Wood Properties of Exotic Hardwoods.- 2.4.4.1 Exotic Hardwoods Other than Eucalyptus.- 2.4.4.2 Wood of Eucalyptus When Grown as an Exotic.- 3 Variation Within and Among Ttees.- 3.1 Introduction.- 3.2 Tree to Tree Variability.- 3.3 Variation of Wood Properties Within Trees.- 3.3.1 Wood Differences Within Annual Rings.- 3.3.2 Wood Variability at Different Locations Within a Tree.- 3.4 The Juvenile Wood Concept.- 3.4.1 Occurrence of Juvenile Wood.- 3.4.2 Juvenile Wood and Growth Rate.- 3.4.3 Importance of Juvenile Wood.- 3.4.4 The Properties of Juvenile Wood.- 3.4.5 Can the Amount of Juvenile Wood Be Changed?.- 3.4.6 Utilization of Juvenile Wood.- 3.4.7 Summary of Juvenile Wood.- 3.5 Variation from the Tree Center to the Bark.- 3.5.1 Radial Trends in Wood Properties of Conifers.- 3.5.1.1 The Hard Pines - Specific Gravity.- 3.5.1.2 Other Conifers - Specific Gravity.- 3.5.1.3 Radial Changes in Conifer Wood of Properties Other than Specific Gravity.- 3.5.2 Radial Trends in Hardwoods.- 3.5.2.1 Specific Gravity.- 3.5.2.2 Other Wood Characteristics.- 3.6 Variation from the Base to the Top of the Tree.- 3.6.1 Breast Height to Total Tree Correlations.- 3.7 The Effect of Total Tree Age on Wood.- 4 Wood Property Variation as Related to Tree Form and Reaction Wood.- 4.1 Introduction.- 4.2 Wood Properties Associated with Poor Tree Form.- 4.2.1 Solid Wood Products.- 4.2.2 Fiber Products.- 4.2.2.1 The Effect of Limbs Upon Fiber Products.- 4.3 Reaction Wood.- 4.3.1 Compression Wood - Conifers 143.- 4.3.1.1 Characteristics of Compression Wood.- 4.3.1.2 Effects of Compression Wood.- 4.3.2 Tension Wood - Hardwoods.- 4.3.2.1 Characteristics of Tension Wood.- 4.3.2.2 Effects of Tension Wood.- 4.4 Methods to Improve Tree Form.- 4.4.1 Better Forest Management.- 4.4.2 Use of the Proper Seed Source.- 4.4.3 Breeding for Branching Characteristics and Bole Straightness.- 4.4.3.1 Summary of Form Improvement Through Genetics and Silviculture.- 5 The Effect of Growth Rate on Wood Properties.- 5.1 Introduction.- 5.1.1 Patterns in Wood Production Resulting from Growth Rate Differences.- 5.1.1.1 Growth Rate - Wood Property Grouping of Forest Trees.- 5.1.2 Literature on Growth Rate and Wood Properties..- 5.2 Growth Rate and Wood Specific Gravity in Conifers.- 5.2.1 Growth Rate - Specific Gravity Relationship in the Hard Pines.- 5.2.1.1 Summary - Specific Gravity and Growth Relationships in Hard Pines.- 5.2.2 Growth Rate - Specific Gravity Relationships in Other Conifers.- 5.3 Growth Rate and Wood Specific Gravity in Hardwoods..- 5.3.1 Specific Gravity and Growth Rate in Ring-Porous Hardwoods.- 5.3.2 Specific Gravity and Growth Rate in Diffuse- Porous Hardwoods.- 5.4 Summary of Growth Rate Effects on Specific Gravity.- 5.5 Cell Characteristics and Growth Rate.- 5.5.1 Summary of the Relation of Cell Length to Growth Rate.- 5.6 Growth Rate and Aesthetic Qualities of Wood.- 5.7 Practical Application of Wood Changes Caused by Growth Rate Differences.- 6 Wood Properties Affected by Environmental, Biological, and Other External Agencies.- 6.1 Introduction.- 6.2 Effect of Site, Soil, and Climate on Wood Properties.- 6.2.1 Soil Properties and Wood.- 6.2.2 Summary - Effect of Site, Soil, and Climate on Wood Properties.- 6.3 Moisture Availability and Wood Properties.- 6.3.1 Moisture Effects on Wood - A Summary.- 6.4 Miscellaneous Biological Factors that Affect Wood Properties.- 6.4.1 Forest Pests and Wood.- 6.4.1.1 Disease and Wood Properties.- 6.4.1.2 The Influence of Insects on Wood.- 6.4.1.3 Effects of Other Pests on Wood Properties.- 6.4.2 Compass Direction in the Tree Stem.- 6.4.3 Temperature, Light, and Wood Production.- 6.4.4 Position of the Tree in the Stand.- 6.5 Unusual Causes for Wood Variability.- 6.6 Growth Stresses and Strains in Tree Stems.- 7 The Effect of Silvicultural Practices on Wood Properties.- 7.1 Introduction.- 7.2 Effect of Nutrient Differences and Fertilization on Wood.- 7.2.1 Fertilizing Conifers.- 7.2.2 Fertilizing Hardwoods.- 7.2.3 Wood Uniformity Following Fertilization.- 7.3 Tree Spacing and Wood Properties.- 7.3.1 Stocking Control by Thinning as Related to Wood Properties.- 7.3.2 Plantation Spacing and Wood Properties.- 7.4 Effect of Pruning on Wood.- 7.4.1 Direct Effect of Pruning on Wood Properties.- 7.4.2 Pruning to Improve Tree Form and Quality.- 7.4.3 Other Considerations About Pruning.- 7.5 Planting Techniques and Wood Properties.- 7.6 Resin Tapping, Resin Induction, and Wood Properties.- 7.7 Wood Properties of Coppice and Root Sprouts.- 8 Control of Wood Properties by Breeding.- 8.1 Genetics of Wood Properties.- 8.1.1 What Are Genetic Differences and How Are They Measured?.- 8.1.1.1 Types of Genetic Variation.- 8.1.1.2 What Kind of Tests Are Necessary to Determine Genetic Variation?.- 8.1.1.3 How Is Genetic Control Measured?.- 8.2 Genetic Control of Wood Specific Gravity.- 8.2.1 What Are the Components of Wood Specific Gravity?.- 8.2.2 Inheritance of Wood Specific Gravity in Conifers.- 8.2.2.1 Genetic Variation Among Provenances.- 8.2.2.2 Stand to Stand Variation in Specific Gravity.- 8.2.2.3 Tree to Tree Variation in Specific Gravity.- 8.2.3 Inheritance of Wood Specific Gravity in Hardwoods.- 8.3 Genetic Control of Wood Properties Other than Specific Gravity.- 8.3.1 Latewood Percent.- 8.3.2 Cell Length.- 8.3.3 Tracheid Diameter and Wall Thickness.- 8.3.4 Chemical Compo…