Logging
From Free net encyclopedia
- For articles about other types of logging, see data logging or well logging.
Image:Loggers.jpeg Image:Truck load of ponderosa pine, Edward Hines Lumber Co, operations in Malheur National Forest, Grant County, Oregon, July 1942.jpg
Logging is the practice of felling (cutting down) trees, and removing them from the forest in order to use the wood as an economic resource. Standing trees viewed as a potential economic resources are termed timber.
Most conventional logging is either for pulpwood production for the manufacture of paper products or for sawlogs for lumber production. In the United States, standard softwood sawlogs are sixteen feet long, whereas hardwood sawlogs are typically eight feet in length. Trees may be referred to as "two-saw-log-trees", for instance, meaning that they have a clear bole for at least 34 (softwood) or 17 feet (hardwood) (after allowing 12-18 inches for the stump).
A significant amount of logging is also done for firewood production, and, today, a very large and growing amount of logging is being done for chipwood production.
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Harvest Methods
There are three basic types of logging systems:
Tree-length
Trees are felled then delimbed and topped at the stump. The log is then transported roadside, often by skidding, where it is bucked at a landing and loaded on a truck. This leaves the slash in the cut area.Full-tree
Trees are felled and transported roadside with top and limbs intact. In the yarding step, a grapple skidder grabs each bunch in its grapple and drags them to the landing. Bunches can be taken individually or in low multiples. Next, each stem is cleaned of limbs and cut to length. This is done with chainsaws or log processors. Log processors come in two general varieties, referred to colloquially as "strokers" and "dangler-heads". Next, the processed logs are loaded onto trucks, then sent to their destination, most often a lumber mill. Loggers have been known to use many different devices to load trucks with in times of need, including bucket-and-thumb excavators and forwarders. This method has the disadvantage of leaving large piles of slash to be disposed of. Full tree harvesting also refers to utilization of the entire tree including branches and tops.Cut to Length
In cut to length trees are felled delimbed and bucked and sorted (pulpwood, sawlog, etc.) at the stump area leaving limbs tops and sawdust in the forest. Some falling is performed by machines called "harvesters", which can chop the tree down, process it, and then place it in bunks to be brought to the landing.
Silvicultural Systems
Clearcutting
The most common and most criticized method of timber harvest in industrial operations is clearcutting, a practice that removes essentially all the trees in a selected area. In the case of a pure-age stand, such as a plantation, or in certain even-aged mature forests, such as some of the virgin Douglas-fir stands of the West, virtually all trees are cut. Clearcutting is also the most economically-efficient way to remove timber but treatment following a clearcut can lead to higher costs. Large poorly planned clearcuts are far more destructive than cuts that take into consideration natural topography, and bioregions. There are supportable claims that clearcutting can be an ecologically healthy forestry practice, mimicking the effects of a natural disturbance. The effects of sustainable clearcutting can mimic the effects of a forest fire or other natural disturbance in a number of important ways. In fact, some tree species, referred to as "shade intolerant" species, only regenerate well in bright sunlight, as in after a clearcut. Conscientious logging will leave standing snags and a mosaic of small "residual patches" for wildlife, and organic matter such as "slash piles" of unusable material are left on-site as ash to fertilize the soil or as partly-burnt wood that will quickly decay into the soil. If logged on frozen ground with low ground pressure machinery, or even horses, the ground can be left generally undisturbed and unbroken which can let groundcover regenerate quickly. In the case of a poorly planned larger (over 1 km²) clearcut, there are few or no residual patches or wildlife snags left behind and the ground will be highly disturbed and compacted; erosion and poor forest regeneration will result. Most forest managers do not consider large clearcuts to be appropriate in a forest managed for multiple uses. Some forest types are especially intolerant of clearcutting exposing soils to direct sun and winter rains, which damages soil nutrients and fungi required for healthy forests.
Selection cut
Selection cutting is the practice of removing mature timber or thinning to improve the timber stand. This system is used to maintain uneven-aged stands to protect forest soils and to maintain wildlife habitat. A particular type of selective cutting that targets only the highest-quality trees of certain species is termed high-grading, which ultimately results in much lower-quality woodlands. If the best trees are cut removing them from the seedstock, an evolutionary pressure towards lower quality results. High-grading also lowers the quality of the remaining forest by leaving undesireable tree species standing, as well as poorly formed trees from desirable species. This can create conditions where no substantial quality timber will naturally grow for many decades. Selection cutting may include opening up areas to allow tree species that require large amount of light to grow but that are not large enough to meet the legal definition of a clearcut.
Overstory removal
Overstory removal or sheltwood cutting is a variation of select cutting. In this method all the large trees are taken and the understory of saplings and smaller trees are left for regeneration. Overstory removal requires care be used to avoid residual stand damage.
Logging and the environment
Harvesting on steep slopes can lead to erosion. Harvesting adjacent to streams can decrease water quality and increase water temperatures. Logging on wetlands or saturated soils can cause ruts, change drainage patterns. The use of heavy machinery in the forest can cause soil compaction. These problems can be mitagated by using best management practices. These practices set standards for building roads reducing erosion and establishment of riparian strips. Harvesting in high value ecologically sensitive lands can lead to habitat loss. Ecologically important lands should be set aside as reserves.
A problem with poorly operated forestry practices, especially in the eastern North American hardwood forests, is the problem of colonization of the forest area by invasive exotics. In a normal, intact forest, or even in a carefully-managed woodlot, such species find it very difficult to gain a toe-hold.
Logging roads
As most logging is done far from developed areas, roads must be constructed for access. These are narrow, unpaved, and usually have no hard shoulder or guardrails. Bridges, if any, are invariably only wide enough for one vehicle. The most common traffic on these roads will be logging trucks, which, when loaded, can carry up to 4,500 kg of wood. As such, drivers on logging roads generally follow one simple rule: A loaded logging truck has the right of way. This is regardless of what the local motor vehicle code may actually say. In areas where this practice is regulated (or is supposed to be) non-highway roads with heavy logging traffic may be "radio-controlled", which is to say a CB radio on board any vehicle on the road is advised for safety reasons.
Construction of these roads, especially on steep slopes, increases the risk of erosion and landslides which can lead to increases in downstream sedimentation. The major source of sediment, (estimated to be about 90% ) from erosion in logging operations is from logging roads, which continues long after operations are completed in the area. The decommissioning of these roads involves the restoring of natural habitat, which can be quite expensive, usually as much as it cost to construct the road in the first place. However, a new alternative, mycofiltration, which is the use of mushrooms to prevent erosion, has been developed at a far lesser expense.
The cost to the public (in public forests) of such road-building varies with each jurisdiction and the type of logging licence. Although many roads are justified to the public as providing access for recreational and other non-logging users, they are often quickly "decommissioned" after their use to log extraction is at an end, and become relatively useless to other vehicular users. Mountainbikers and hikers and others still can access these roads, but they are not maintained.
Forest regeneration, silviculture and biodiversity
In clearcuts where natural regeneration is insufficient, sound forestry legislation will demand that a logging company plant seedlings to aid the natural regeneration of the forest. Some argue that treeplanting leads to a "monoculture" forest which destroys the biodiversity of the area. Most seedlings used in reforestation come from the seeds found in the recently cut forest as these trees are naturally adapted to the area. In many areas multiple species will be planted according to the smaller ecoregions of the cutblock ie) lodgepole pine, white or black spruce, cedar, etc. However, clearcutting exposes previously shaded forest soils to direct sun and rainstorms which damage the microbiol diversities required for healthy forest growth.
Riparian strips or zoning is an important forest management practice in which trees are left standing along waterways to protect the banks and water quality. Failure to do so has historically exacerbated flooding, erosion and siltation, and caused local extirpations of sensitive plant and animal species. Some of the most marked effects of large-scale clearcutting, including the stream corridors, has been seen in the American Pacific Northwest, where salmon streams have lost their salmon-supporting capability, and local populations of salmon and even subspecies have become extinct as a result.
Image:Biodiversity on clearcut.jpg
The negative portrayal of logging by the media and popular culture
The logging industry is often portrayed in the media and popular culture as one of the most ecologically destructive corporate practices on earth. However, logging companies contend that despite some notable cases of severe environmental degradation by large, multinational logging operations, agriculture, livestock grazing, mineral mining, the petroleum industry and urban sprawl are even greater contributors to deforestation and ecological degradation. As an example, they cite that a house built out of steel, plastic and concrete requires more energy and non-renewable resources to produce than a house built with wood products.
See also
External links
- Horse Logging (Enviro-friendly) in Wales (UK)
- Boreal forests
- Consumers companies linked to forest destruction
- NASA Earth Observatory
- CTL Logging (Enviro-friendly)
- America's Only National Logging & Forestry Magazine
- Movie of logging in Maine, 1906
- Bailey's Logger and Woodsman Supplies
- Logging Lingo
- Palm Oil as a smokescreen for Loggingde:Fälltechnik