Қағаз өндірісі үшін ағаш шикізаты және оның экологиялық салдары

Timber intended for processing into wood pulp for paper production
Pulpwood can be defined as timber that is ground and processed into a fibrous pulp. It is a versatile natural resource commonly used for paper making but also made into low grade wood and used for chips, energy, pellets, and engineered products. Pulpwood can be derived from most types of trees. Categorizing trees into hardwood and softwood is the easiest way to characterize types of paper produced from pulpwood. Softwoods are the preferred raw material for strong papers, due to the length and slimness of the fibres. Low density softwoods, such as firs with thin walled fibres are preferred for papers with high demands for bonding related strength characteristics. Some of these characteristics include tensile, burst, and surface strength.

Paper production is the most common and main use for pulpwood. Paper can be produced from both hardwood and softwood trees, and each species for both types of trees have specific and unique properties that make the type of paper and other products produced differ. The short fibres of hardwoods trees produce smoother and more uniform paper, like printing paper. Softwood trees have longer fibres that produce industrial papers like newsprint.

The chemical method of breaking down wood pulp to make paper is more commonly used and energy efficient compared to the mechanical method. In the chemical method, the wood chips are 'cooked' in large tanks. The tanks are called digesters, and are like pressure cookers. Chemicals, referred to as 'cooking liquor' help break down wood chips into a mass of fibres.

To help feed pulp and paper mills, vast monocultures of conifers eucalyptus, acacia, and other species are being established both in the North and South, where fast tree growth, inexpensive land and labour, and lavish subsidies combine to make wood cheaper. A exotic trees invade native woodlands, grasslands, farmlands and pastures, consequences in most countries include impoverishment, environmental degradation, and rural strife. Plantations are full of trees similar to forests, but they differ greatly. A forest is a complex, self regenerating system, consisting of soil, water, microclimates, energy, a diverse ecosystem with a wide variety of plants and animals in mutual relation. In contrast, a commercial plantation is a cultivated area whose species and structure have been simplified dramatically to produce only a few goods, such as lumber, fuel, resin, oil or fruit. The trees in a plantation have a small range of species and ages, and require extensive and consistent human intervention. Plantations normally replace crops, grasslands, or scrub forests. Since they are used for commercial necessities, they are established on healthy soil, with their objective being short cycles of rapid growth that requires a certain level of fertility and water supply. Therefore, they tend to occupy areas already being used by local people. Salvage cutting is the removal of trees that have been killed or damaged by insects, disease, wind, ice, snow, volcanic activity, or wildfire. The purpose of salvage cutting is to recover the economic value of trees before they decay. Dead trees decay quickly, and the timing of salvage cutting is crucial to capture as much economic value as possible. Post fire salvage cutting helps manage fuels and future fire behaviour, as long as logging slash is treated after the harvest.

Saw residuals are used as pulpwood. The most important of these are the side cuttings from lumber edger. This gives wood with almost only sapwood and no heartwood. The sapwood is easier to pulp. due to a more open structure and less content of extractive than the heartwood. The fibre length of sapwood is generally longer than the fibre length of heartwood. The sapwood is also normally lighter and that is an advantage when producing mechanical pulp as less bleaching of wood pulp is needed. Sawdust 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.

Chemical composition of pulpwood (%) Wood Cellulose Lignin Mannan Araban Xylan Aspen 56.5 16.3 2.3 0.4 16.0 Paper Birch 44.5 18.9 1.5 0.5 24.6 Red maple 44.8 24 3.5 0.5 17.3 Balsam fir 47.7 29.4 12.4 0.5 4.8 Jack pine 45.0 28.6 10.8 1.4 7.1 White spruce 48.5 27.1 11.6 1.6 6.8