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Clearcutting

Clearcutting, otherwise known as clearfelling, is a controversial forestry/logging practice in which the majority or all of the trees in an area are uniformly cut down. Clearcutting, in addition to shelterwood and seed tree harvests, is utilized by foresters to construct certain types of forest ecosystems and to encourage select species that require plentiful sunlight or grow in large, even-age stands. Logging companies and forest-worker unions in certain countries support the practice for scientific, economic, and safety reasons. Detractors view clearcutting as synonymous with deforestation, destroying natural habitats and encouraging climatic change. Clearcutting is the famous and economically profitable manner for logging. It serves a dual purpose: marketing harvested wood and clearing the land for cattle farmers.

Various methods of clearcutting exist; the most common professional practices are standard clearcut, meaning the removal of every stem so no canopy remains. Patch clearcut, meaning removal of all the stems in a limited and predetermined area. Strip clearcut, meaning removal of all the stems in a row, normally placed perpendicular to the prevailing winds in order to minimize the potential of windthrow. Clearcutting-with-reserves, meaning the removal of most of the standing stems, saving a few that are reserved for other purposes. Slash-and-burn, meaning the permanent conservation of tropical and subtropicals for agricultural purposes. Selective Harvesting, meaning logs are selectively harvested around old-growth trees, whose durability and long interconnectedness with the ecosystem offer unique habitats for animals and plants. This method is used for the sole purpose of harvesting wood.

Clearcutting has the potential to cause negative impacts, both for humans and local fauna and flora. A study performed by the University of Oregon found that in certain zones, areas that were clear cut had almost three times the amount of erosion caused by slides. When the roads that are required for clearcutting were factored in, the increase in slide activity seemed to be about five times greater compared to nearby forested areas. It can also lead to an increased possibility of rapid runoff, lost of economic sustainability in that no timber products are available for a long period of time after clearcutting, loss of habitat for some species of wildlife, unattractive visual effect, greater possibility of unwanted shrubbery and grasses becoming established, in addition to a decrease in property values; diminished recreated, hunting, and fishing opportunities.

This act of clearcutting can be practiced to encourage the proliferation and growth of tree species that need high light intensity. Usually, a harvest area that is wider than double the height of the adjacent trees will no longer be subject to the moderating influence of woodland on the microclimate. The width of the area of harvest can thus determine which species will come to dominate. It can be used by foresters as a means of mimicking a natural disturbance and increasing primary successional species. It’s also been proved to be effective in constructing animal habitat and browsing areas, which otherwise wouldn’t exist without natural stand-replacing disturbances. Within temperate and boreal climates, clearcutting can have an effect on the depth of the snow, which is normally greater in a clearcut area than in the forest because of a lack of interception and evapotranspiration. This causes less soil frost, which combined with higher levels of direct sunlight results in snowmelt that occurs earlier in the spring. Clearcuts are also used to help regenerate species that can’t compete in mature forests. More recently, forest managers have discovered that clearcutting oak stands helps regenerate oak forests in areas of poor soil. The tree canopies in the oak forests frequently shade out the ground, making it impossible for newly sprouted oaks to grow. By taking away the older trees, the saplings stand a change of recruiting into the forest.

Environmental groups criticize clearcutting as destructive to the soil, water, wildlife, atmosphere, and recommend the use of sustainable alternatives. Clearcutting has a significant impact on the water cycle. Trees hold topsoil and water. Clearcutting within forests removes the trees which would otherwise have been transpiring large volumes of water and also physically damages the understorey level of grasses, lichens ferns, mosses etc. All of this biomass has the ability to retain water during rainfall. The removal or damage of the biota decreases the local capacity to retain water which can exacerbate flooding and can cause increased leaching of nutrients from soil. It also prevents trees from shading the riverbanks, which raises the temperature of riverbanks and rivers, encouraging the extinction of some fish and amphibian species.

Image Caption: Clearcutting in Southern Finland. Credit: Tero Laakso / Wikipedia (CC BY 2.0)

Clearcutting


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