Logging
Categories: Forestry | Resource extraction | Environmentalism
- For another article about a different type of logging, see data logging.
Logging is the practice of cutting down trees, then cutting out their central boles (the clear trunk or central stem) and possibly branches in order to use the wood directly or to market it 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 sawlogs are sixteen feet long. Trees may be referred to as "two-saw-log-trees", for instance, meaning that they have a clear bole for at least 34 or so feet (allowing for the remaining 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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Logging methods
There are two principle variants of clearcutting. In the first, just mentioned, all marketable trees are removed and trees too small for market, including saplings, are left. However, clearcutting in the case of pulpwood production usually involves cutting away all woody plants, often producing a "shaved" effect. This may be also true in the case of chipwood production. This type of clearcut area takes a longer time to regenerate forest and suffers more erosion than does mixed-stand clearcutting that leaves younger trees intact.
There are supportable claims that clearcutting can be an ecologically healthy forestry practice, mimicking the effects of a natural disturbance. However, clearcutting is also the most economically-efficient way to remove timber. Obviously, large poorly planned clearcuts are far more destructive than cuts that take into consideration natural topography, and bioregions. The effects of sustainable clearcutting can mimic the effects of a forest fire or other natural disturbance in a number of important ways. Conscientious logging will leave standing snags and 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 lighter 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.
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, but clearcutting opens up the land to large-scale colonization by such species as Japanese Honeysuckle, Multiflora Rose, Kudzu, Oriental Bittersweet, Garlic Mustard, and other species which take over the ecosystem and displace other plant species and dependent animal species.
Selective logging vs. clearcut logging
Selective cutting is the practice of only taking certain trees that are deemed the most desirable for harvest, and leaving the rest. This is a practice most often engaged in by woodlot owners who wish to sustain their timber yield. Only the largest, most commercially viable trees are cut, leaving younger trees and non commercial trees to continue to grow. For instance, trees that were originally open-grown have much lower value for lumber than do forest-grown trees, and strongly cross-grained trees such as elms tend to be avoided for firewood production. 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.
This can be a problem with selective logging, if the best trees are cut removing them from the seedstock, an evolutionary pressure towards lower quality results. Many tree species require large amount of light to grow therefore, trees will grow faster in an open area than in a gradually "thinned" forest. However, selective logging can allow for higher production over time, but this practice does not maximize profit. 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.
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 always 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.
Construction of these roads almost invariably accelerates erosion and increases downstream sedimentation. In fact, the major source of sediment 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.
Forest regeneration, silviculture and biodiversity
In clearcuts where natural regeneration is poor, 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.
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.