Pulpwood
Encyclopedia
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
with the principal use of making wood pulp
Wood pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
for paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
production.
Applications
- Trees raised specifically for pulp production account for 16% of world pulp production, old growth forestOld growth forestAn old-growth forest is a forest that has attained great age , and thereby exhibits unique ecological features. An old growth forest has also usually reached a climax community...
s 9% and second- and third- and more generation forests account for the balance. ReforestationReforestationReforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation....
is practised in most areas, so trees are a renewable resource. - Pulpwood is also used as the raw material for some wood products, such as oriented strand boardOriented strand boardOriented strand board, also known as OSB and SmartPly , is an engineered wood product formed by layering strands of wood in specific orientations. In appearance, it may have a rough and variegated surface with the individual strips Oriented strand board, also known as OSB (UK) and SmartPly (UK &...
(OSB). - There is an increasing demand for pulpwood as a source of 'green energy' by the bio-energy sector.
Properties
The fibre length of the cellulose fibresCellulose fiber
Cellulose fibers are fibres of cellulose from any source, either natural or manufactured.-Textile:In the textile industry regenerated cellulose is used as fibers such as rayon, . Cellulose fibers are manufactured from dissolving pulp...
is the most important parameter of the pulpwood and determines what it may be used for. The first separation is into softwood
Softwood
The term softwood is used to describe wood from trees that are known as gymnosperms.Conifers are an example. It may also be used to describe trees, which tend to be evergreen, notable exceptions being bald cypress and the larches....
and hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
, that have long and short fibres respectively. In paper production
Paper mill
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags and other ingredients using a Fourdrinier machine or other type of paper machine.- History :...
fibres from softwood gives tensile strength
Tensile strength
Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...
and fibres from hardwood gives opacity
Opacity (optics)
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...
.
Logging
In the loggingLogging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
of mixed forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
stands, the better tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s are usually used for sawlogs for lumber
Lumber
Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
production, while the inferior trees and components are harvested for pulpwood production. Pulpwood usually derives from four types of woody materials in a mixed logging operation:
- Open-grown trees, that are heavily branched low on the trunk, and so make poor sawlogs.
- Dead or diseased trees.
- Tops cut from trees harvested for sawlogs (branches are rarely used since they contain little usable wood after the bark has been removed).
- Small trees, too small to harvest for sawlogs.
Natural forest stands may also be harvested solely for pulpwood where, for various reasons, the value of the trees as sawlogs is low. This may be due to the predominant species in the forest stand (for example, some aspen
Aspen
Populus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by...
forests in northern North America), or to the relative proximity of the nearest sawmill or pulp mill
Pulp mill
A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fibre board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical or fully chemical methods...
.
Plantations
Pulpwood is also harvested from plantations/tree farms established for the specific purpose of growing pulpwood, with little or minimal sawlog production. MonocultureMonoculture
Monoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...
s of species intended specifically for pulpwood include loblolly/slash pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
in the southern USA; various species of eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
(most commonly Eucalyptus globulus
Eucalyptus globulus
The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30 to 55 m tall. The tallest currently known specimen in Tasmania is 90.7 m tall...
and Eucalyptus grandis
Eucalyptus grandis
Eucalyptus grandis, commonly known as the Flooded gum or Rose gum, is a tall tree with smooth bark, rough at the base fibrous or flaky, grey to grey-brown...
) in Latin America, Iberian Peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
, Australia, south-east Asia and southern Africa and acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
(most commonly Acacia mangium
Acacia mangium
Acacia mangium is a species of flowering tree in the pea family, Fabaceae, that is native to northeastern Queensland in Australia, the Western Province of Papua New Guinea, Papua, and the eastern Maluku Islands. Common names include Black Wattle, Hickory Wattle and Mangium...
) in south-east Asia and southern Africa.
Salvage cuttings
Salvage cuts after forest fires, tornadoTornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...
es, hurricanes, or other natural disasters are often used for pulpwood. An alternative source of wood for use in kraft pulping
Kraft process
The kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
is recovered lumber from demolition, industrial processing of wood and wooden pallets.
Wood residuals
Saw residuals are used as pulp wood. The most important of these are the side cuttings from lumber edgersLumber edger
A lumber edger is a saw used to straighten and smooth rough lumber or bowed stock by making a cut along the sides of the boards. The result of this process is dimensional lumber....
. This gives wood with almost only sapwood
Sapwood
Sapwood may refer to:* Sapwood, the part of living wood where sap flows, as distinct from the heartwood, where it doesn't* SS-6 Sapwood, the NATO reporting name for the R-7 Semyorka intercontinental ballistic missile...
and no hearthwood. The sapwood is easier to pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
. due to a more open structure and less content of extractives
Black liquor
Black liquor is the spent cooking liquor from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers....
than the hearthwood. The fibre length of sapwood is generally longer than the fibre length of hearthwood. The sapwood is also normally lighter and that is an advantage when producing mechanical pulp as less bleaching
Bleaching of wood pulp
Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter. The main use of wood pulp is to make paper where whiteness is an important characteristic...
is needed.
Earlier sawdust
Sawdust
Sawdust is a by-product of cutting lumber with a saw, composed of fine particles of wood. It can present a hazard in manufacturing industries, especially in terms of its flammability....
had some limited use in paper production. It gives very short fibres that are suitable as part of the furnish for paper tissue and writing papers. Saw blades have become thinner and with smaller teeth making the sawdust too small as fibre source.
Economical important pulpwoods
- Hardwoods
- AcaciaAcaciaAcacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
- AspenAspenPopulus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by...
- BirchBirchBirch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
- EucalyptusEucalyptusEucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
- MapleMapleAcer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
- Pacific AlbusPacific AlbusPacific Albus is a hybrid Poplar grown in the Pacific Northwest, near Boardman, Oregon. Its name is from the Latin word albus meaning white. It has similar characteristics to Aspen and Cottonwood.-History:...
- Softwoods
- PinePinePines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
- SpruceSpruceA spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
Chemical composition of some pulpwoods
| Chemical composition of pulpwood (%) | |||||
|---|---|---|---|---|---|
| Wood Wood Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression... |
Cellulose Cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units.... |
Lignin Lignin Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood... |
Mannan Mannan Mannan is a plant polysaccharide that is a polymer of the sugar mannose.Detection of mannan leads to lysis in the mannan-binding lectin pathway.It is generally found in yeast, bacteria and plants. It shows α linkage. It is a form of storage polysaccharide.-See Also:Mannan Oligosaccharides... |
Araban Araban Araban is a district of Gaziantep Province of Turkey. The population is 9,863 as of 2010.... |
Xylan Xylan Xylan is a generic term used to describe a wide variety of highly complex polysaccharides that are found in plant cell walls and some algae. Xylans are polysaccharides made from units of xylose .... |
| Aspen Aspen Populus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by... |
56.5 | 16.3 | 2.3 | 0.4 | 16.0 |
| Paper Birch Paper Birch Betula papyrifera is a species of birch native to northern North America.-Description:... |
44.5 | 18.9 | 1.5 | 0.5 | 24.6 |
| Red maple Red Maple Acer rubrum , is one of the most common and widespread deciduous trees of eastern North America. It ranges from the Lake of the Woods on the border between Ontario and Minnesota, east to Newfoundland, south to near Miami, Florida, and southwest to east Texas... |
44.8 | 24 | 3.5 | 0.5 | 17.3 |
| Balsam fir Balsam Fir The balsam fir is a North American fir, native to most of eastern and central Canada and the northeastern United States .-Growth:It is a small to medium-size evergreen tree typically tall, rarely to tall, with a narrow conic crown... |
47.7 | 29.4 | 12.4 | 0.5 | 4.8 |
| Jack pine Jack Pine Jack pine is a North American pine with its native range in Canada east of the Rocky Mountains from Northwest Territories to Nova Scotia, and the northeast of the United States from Minnesota to Maine, with the southernmost part of the range just into northwest Indiana... |
45.0 | 28.6 | 10.8 | 1.4 | 7.1 |
| White spruce White Spruce Picea glauca is a species of spruce native to boreal forests in the north of North America, from central Alaska east to Newfoundland, and south to northern Montana, Minnesota, Wisconsin, Michigan, upstate New York, Vermont, New Hampshire, and Maine; there is also an isolated population in the... |
48.5 | 27.1 | 11.6 | 1.6 | 6.8 |