General Description of Timber Yielding Plants

What are Timber plants?

• Timber plants, fundamental to human civilization, encompass a variety of tree species cultivated primarily for their wood. This natural resource has been essential throughout history, serving various functions from the construction of shelters to the creation of tools and utensils. As humanity has evolved, so too has the utilization of timber, which continues to be integral to modern society despite the advent of alternative materials such as metals and synthetics.
• The term “timber” refers specifically to trees that are harvested for lumber, a terminology commonly used in the United States and Canada. Timber trees can be classified based on their wood type into softwoods, semi-hardwoods, and hardwoods. Hardwood, derived from angiosperms, particularly dicotyledonous plants, is characterized by its durability and longevity. This quality makes hardwoods such as oak, birch, and beech particularly sought after for high-end applications, including furniture, flooring, and even residential construction. Their dense structure provides enhanced resistance to wear, making them ideal for enduring environments.
• In contrast, softwoods originate from gymnosperms, primarily coniferous species. Although generally less durable than hardwoods, softwoods serve important roles in the economy, being commonly used in products like crates, crafts, and paper. The distinction between these wood types is crucial for understanding their applications, as each has unique characteristics that dictate its suitability for various uses.
• The products derived from timber, commonly referred to as timber products, include an array of items, from structural materials to decorative finishes. These wood products, often obtained from the stems and other woody parts of plants, are characterized by a high strength-to-weight ratio, making them versatile for numerous applications. The inherent properties of wood, such as its workability and aesthetic appeal, contribute to its persistent demand across various industries.
• Timber not only serves practical purposes but also embodies an ecological significance. Overexploitation of forests has raised concerns regarding sustainability and resource management. Therefore, responsible forestry practices are essential to preserve these valuable ecosystems. Effective management ensures that timber plantations remain viable, allowing for the continued use of wood without jeopardizing forest health.

Important timber yielding plants

1. Tectona grandis

Tectona grandis, commonly known as teak, is a prominent species within the family Verbenaceae. Renowned for its exceptional qualities, teak is one of the most significant commercial timber crops in tropical regions.

• Distribution: Tectona grandis is native to Southeast Asia and Malaya, thriving primarily in countries like Myanmar and Thailand, which boast extensive teak forests. In India, teak is cultivated across several states, including Madhya Pradesh, Maharashtra, Gujarat, Karnataka, Rajasthan, Kerala, Tamil Nadu, and Andhra Pradesh.
• Characteristics:
  • Morphology: Tectona grandis is a large, deciduous tree that can reach heights of up to 40 meters with a bole diameter of approximately 1 meter. This species has a lifespan that may exceed 200 years, highlighting its long-term viability as a timber source.
  • Flowers and Leaves: The tree produces fragrant, small white flowers. Its leaves are large, ovate-elliptic, and typically papery, often exhibiting a hairy texture on the lower surface.
  • Fruits: The fruit of the teak tree is globose in shape.
• Wood Properties: Teak is highly esteemed for its wood, which is characterized by exceptional durability and water resistance. The wood’s qualities include:
  • Sapwood vs. Heartwood: The sapwood is pale and susceptible to termite attacks and fungal rot, while the heartwood is golden yellow to golden brown when freshly cut, darkening with age. The heartwood exhibits relative immunity to insect damage.
  • Texture and Stability: Teak wood is greasy to the touch and has a scent reminiscent of old leather. It possesses a coarse and uneven texture with straight grain. Notably, it is resistant to warping, splitting, or cracking, which makes it particularly valuable for various construction applications.
  • Weight and Density: The average weight of dry teak wood ranges from 609 to 689 kg/m³. It exhibits distinct growth rings, is ring porous, and features larger vessels in early wood compared to late wood. These vessels are often arranged in concentric circles in transverse sections, and tyloses (growths that can block vessels) are quite common.
• Uses: The applications of teak are extensive and varied. Teak ranks among the world’s finest timbers, serving critical roles in:
  • Construction: It is widely used in the building of houses, bridges, and other structures due to its strength and durability.
  • Shipbuilding: Teak wood is preferred over oak for constructing ships, highlighting its superior quality in marine applications.
  • Furniture and Plywood: The wood is commonly utilized for making cabinets, flooring, toys, and other furniture items. Additionally, it is favored in plywood manufacturing due to its favorable physical properties.
  • Carving: Teak is also popular for artistic endeavors, such as carving, due to its workability and aesthetic appeal.

2. Dalbergia sissoo Roxb

Dalbergia sissoo Roxb, commonly known as shisham or sissoo, is a prominent species within the Fabaceae family. This tropical tree is highly regarded for its durable and aesthetically pleasing timber, making it a sought-after material for various applications.

• Distribution:
  • Dalbergia sissoo thrives across the sub-Himalayan regions, extending to Assam.
  • It is part of a broader genus of tropical trees that includes other valuable species, such as Dalbergia latifolia (Indian rosewood), which is found in central and southern India and sub-Himalayan tracts.
  • Additional notable species in the Dalbergia genus include D. nigra (Brazilian rosewood), D. melanoxylon (African blackwood), D. retusa (cocobolo), and D. stevensonii (Honduras rosewood).
• Characteristics:
  • Morphology: Dalbergia sissoo is classified as a medium to large deciduous tree, reaching heights of 10 to 15 meters.
  • Leaves: The leaves are compound, typically consisting of about five alternate leaflets. Each petiole measures approximately 15 cm in length, with the leaflets widest at the base and tapering to a fine point.
  • Flowers and Fruits: The tree produces panicles of small, yellow or white papilionaceous flowers that occur in dense clusters on short stalks. The dry fruit takes the form of a pale brown pod, which is flat, thin, and papery, measuring around 7 cm in length, with seeds visible from within the pod.
• Wood Properties:
  • The sapwood of Dalbergia sissoo ranges from white to brownish, while the heartwood can be golden brown to dark brown. This distinction between sapwood and heartwood is clearly demarcated.
  • The average weight of the wood is between 800 and 850 kg/m³, although Indian rosewood exhibits variations where the sapwood is yellowish and the heartwood ranges from dull brown to almost purple.
  • Dalbergia sissoo wood is recognized for its durability, particularly in aquatic environments, and weighs between 800 and 960 kg/m³. While it may not be easy to work with, it carves well, showcasing its potential for artistic applications.
• Uses:
  • The timber from Dalbergia sissoo is prized for high-quality furniture and cabinets, contributing significantly to the craftsmanship in this sector.
  • Besides furniture, the wood serves various construction purposes, including railway sleepers and general-purpose timber.
  • Its applications extend to the production of musical instruments, hammer handles, shoe heels, and tobacco pipes.
  • Furthermore, Dalbergia sissoo wood is suitable for charcoal making and is often used for decorative veneers, enhancing aesthetic appeal in various woodworking projects.

3. Pinus roxburghii, P. wallichiana

Pinus roxburghii and Pinus wallichiana are two notable species within the Pinaceae family, commonly referred to as chir pine and kail pine, respectively. These species are prominent timber sources in India, valued for their unique characteristics and versatile applications.

• Distribution:
  • Pinus roxburghii, known as chir pine, primarily inhabits the outer hill ranges of the Siwalik region and the valleys of the Himalayas.
  • In contrast, Pinus wallichiana, or kail pine, is typically found at higher altitudes in the same geographic regions.
  • Both species are prevalent in northern Indian states, including Himachal Pradesh, Jammu and Kashmir, Punjab, and Uttar Pradesh.
  • Other significant commercial pine species include Pinus strobus (American yellow pine), Pinus monticola (Western white pine), Pinus sylvestris (Scots pine), and Pinus ponderosa (Ponderosa pine).
• Characteristics:
  • Morphology: Pines are generally tall trees characterized by needle-like leaves and distinct male and female cones.
  • Branch Structure: They possess two types of branches: long shoots and short shoots, along with three types of leaves—primordial, scale, and adult.
  • Leaf Arrangement: The triangular scale leaves are lance-shaped and are borne on the long shoots of older trees. Both types of shoots develop in the axils of the deciduous scale leaves.
  • Photosynthesis: Adult leaves are needle-like and are arranged in fascicles (bundles) of two to five, occasionally up to eight or solitary, at the tips of short shoots. These leaves typically contain two or more resin canals, which are crucial for the tree’s defense mechanisms and overall health.
• Timber Classification:
  • Pine timber is categorized into two broad types: soft or white pines and hard, yellow or pitch pines.
  • Soft or White Pines: This category includes species like Pinus roxburghii. Their wood is soft, light-colored, tinged pink in the heartwood, and nearly white in the sapwood. Soft pines typically have needles in bundles of five and are used for products like matches, crates, and rough carpentry.
  • Hard or Yellow Pines: These have a resinous, heavy, hard, and durable wood with a pronounced grain pattern. Although their wood is light and easy to work with, it lacks durability. Examples of hard pines include P. sylvestris and P. ponderosa, which are utilized in construction, including buildings, bridges, and ships.
• Wood Properties:
  • Soft pines have a close-grained structure with thin, nearly white sapwood and scales lacking prickles, making them suitable for lightweight applications.
  • Conversely, hard pines, characterized by coarse-grained, often dark-colored wood, have thick sapwood and persistent leaf sheaths. They typically exhibit a greater amount of resin, contributing to their strength and durability.

4. Cedrus deodara

Cedrus deodara, commonly known as deodar or Himalayan cedar, is a prominent species within the Pinaceae family. Recognized for its impressive size and quality wood, this tree plays a vital role in both ecological systems and human applications.

• Taxonomy:
  • The Cedrus genus comprises four primary species: Cedrus atlantica (Atlas cedar), Cedrus brevifolia (Cyprian cedar), Cedrus libani (Cedar of Lebanon), and Cedrus deodara (Deodar cedar).
  • Additionally, there are several species often referred to as “false cedars,” primarily found in North America, including Alaskan yellow cedar (Cupressus nootkatensis), Bermuda cedar (Juniperus bermudiana), Eastern red cedar (Juniperus virginiana), and others. Although these are not classified under the Cedrus genus, they share similar characteristics and are commonly associated with the term “cedar.”
• Distribution:
  • Cedrus deodara is native to mountainous regions of the Mediterranean and the western Himalayas.
  • This tree predominantly thrives in the northwestern Himalayas, specifically in states such as Kashmir, Himachal Pradesh, Uttar Pradesh, and Punjab, where it has become a critical component of the local ecology and economy.
• Characteristics:
  • Morphology: Deodar is a tall evergreen tree, typically reaching heights of 45 to 60 meters.
  • Foliage and Branching: The tree exhibits horizontal, spreading branches that contribute to its characteristic skyscraper-like appearance. Young trees are covered with smooth, dark-gray bark, which evolves into a brown, fissured, and scaly texture with age.
  • Leaves: The leaves are needle-like, three-sided, and rigid, arranged in a scattered pattern along the long shoots, while dense tufts form at the ends of short spurs.
  • Cones: Female cones are notably large and barrel-shaped, exhibiting a resinous quality, and can appear greenish or purplish. They are borne on short stalks and covered by broad, thin, overlapping woody scales, each featuring a claw-like projection.
• Wood Properties:
  • Cedarwood is characterized as light, soft, resinous, and notably durable.
  • The sapwood is white, while the heartwood is light yellow, darkening to brown upon exposure to air.
  • This timber is prized for its durability and resistance to insect damage. The wood’s texture is fine and uniform, contributing to its suitability for various applications. True cedars, including Cedrus deodara, possess aromatic, often red-tinged wood that resists decay, making them particularly valuable in construction and manufacturing.
• Uses:
  • The applications of deodar wood are extensive. It is commonly used in the construction of railway coaches, beams, posts, doors, window frames, and bridges.
  • Additionally, the wood serves various purposes, including the manufacture of pencils, chests, closet linings, carvings, fence posts, and packaging materials.
  • Furthermore, the distilled oil extracted from deodar wood finds its way into many toiletries, showcasing the tree’s economic significance beyond timber.

Different uses of wood

Wood, as a versatile natural resource, has been employed for a multitude of purposes throughout history. Its unique properties and accessibility make it an invaluable material in various sectors. Below is a detailed exploration of the different uses of wood, encompassing its processing, applications in fuel, construction materials, containers, chemical products, cellulose-derived products, and paper-making.

• Processing Wood for Use:
  • The journey of wood begins with the felling of trees, where the trunk is cut close to the ground, and branches are removed.
  • The main trunk is then sectioned into appropriate lengths known as saw logs.
  • In contemporary practices, powered saws have largely replaced hand saws, facilitating the mechanized processing of fresh logs.
  • The unique characteristics of wood, including its versatility and lack of substitutes, allow it to be utilized in various forms: fuel, construction materials, furniture, containers, and both mechanically and chemically processed products.
• Fuel:
  • Historically, wood has been a primary source of fuel for heating and cooking.
  • While fossil fuels and electricity have increasingly taken precedence, wood remains widely used for fuel purposes.
  • Approximately 90% of oven-dried wood is combustible, making it an efficient energy source.
  • Fuel value varies significantly among wood types, largely influenced by density, chemical makeup, and moisture content.
  • Hardwoods such as beech, oak, maple, and birch are considered the best fuel woods, offering an average calorific value of around 4600 cal/kg.
• Construction Materials:
  • Poles: Utilized mainly for telephone, telegraph, and electrical transmission lines, durable and lightweight coniferous woods are preferred.
  • Pilings: Employed in constructing docks and bridges, these are typically straight, round timbers driven beneath water, with pine and oak as common materials.
  • Posts: Essential for fencing along boundaries, railroads, and highways, various local species can be used based on strength and durability requirements.
  • Mine Timbers: Various wooden supports such as props and crossbars are utilized in mine tunnel constructions to prevent debris falls, with durable hardwoods being the material of choice.
  • Railroad Ties: Serving as supports for railroad tracks, oak is the most commonly used wood, treated for longevity and durability.
  • Veneers: Thin sheets of wood created through peeling, slicing, or sawing logs, with rotary cutting being the most common method.
  • Plywood: Composed of multiple thin sheets of veneer glued under pressure, plywood is valued for its dimensional stability and strength. It is extensively used in construction, furniture, and cabinetry.
• Containers:
  • Cooperage: The craft of creating wooden containers such as barrels and tanks. This industry is divided into slack cooperage for dry materials and tight cooperage for liquids.
  • Woods selected for slack cooperage must be lightweight and elastic, while tight cooperage utilizes stronger hardwoods to prevent leakage.
• Chemical Products:
  • Wood serves as a raw material for numerous chemical products, primarily due to its composition of cellulose, hemicellulose, and lignin.
  • Wood Distillation: An ancient process involving the heating of wood in the absence of air to produce charcoal, pyroligneous acid, and wood gas, among other products.
  • Tapping for Naval Stores: Originally used for pitch, this process yields gum turpentine and gum rosin, which have applications in various industries, including maritime.
• Cellulose-Derived Products:
  • Wood is an essential source of cellulose, used primarily in paper and rayon manufacturing.
  • Manufacture of Wood Pulp: Wood is converted into pulp through mechanical, chemical, or semi-chemical processes.
    • Mechanical Pulping: Involves grinding wood into a fibrous mass, yielding high volumes but retaining lignin, leading to paper deterioration over time.
    • Chemical Pulping: Uses high temperatures and chemical solutions to extract pure cellulose fibers, yielding high-quality paper with lower volumes of pulp.
    • Semi-Chemical Pulping: Combines mild chemical treatment with mechanical defibration, producing a balance between yield and quality suitable for corrugated boards and other applications.
• Paper Making:
  • Historically reliant on cotton and linen rags, wood pulp now constitutes about 97% of the global paper supply, with coniferous woods being the primary source.
  • The process involves washing, screening, bleaching, and beating pulp to enhance quality and prepare it for paper-making machines.
  • Additives such as mineral fillers and sizings are incorporated to improve paper attributes, while various wood species are utilized to achieve desired characteristics in the final product.