Clearfelling
From Free net encyclopedia
Clearfelling or clearcutting is the process where all trees, or nearly all trees in a selected area, are taken in a logging operation. There is no agreed upon minimum area that constitutes a clear cut, but typically a clearcut would be 5 or more acres in size. Areas smaller than this that are "clearcut" would be considered patch cuts.
The reasons for clearcutting can be very different, ranging from greed (taking every tree worth any money) to optimizing the regeneration of a forest (explained below). Not all clearcutting is good, but not all clearcuting is negative or malicious.
Two sub-types of clearcutting exist: the commercial clearcut and the silvicultural clearcut. The former would be the removal of all merchantable trees (trees that could be turned into forest products or sold for such). The latter would be the removal of all trees (and shrubs) whose diameter 4.5 feet above ground level (dbh or diameter at breast height) is equal to or greater than 2 inches.
Commercial clearcutting would typically be done (but not always) by someone simply seeking to maximize the money coming from the logged area. Only trees worth money are removed and nothing is done (therefore saving time and money) with any other trees. However, in an area where abundant seedlings and saplings are already established, clearcutting the larger trees would provide more sunlight to the smaller trees beneath. If this is the case the term "release cut" or "overstory removal" would be more appropriate.
A silvicultural clearcut removes all designated trees 2 inches or greater in diameter at breast height. This isn't done to maximize dollars but rather to maximize the amount of sunlight that reaches the ground. Ecologically this would simulate a massive windstorm, a large fire, or perhaps a large insect or disease outbreak. Commonly clearcuts leave "reserve" trees -trees that won't be cut. These can be left to mimimize the aesthetic impact of a clearcut, to maintain cavity or den trees for wildlife, to maintain biodiversity, or other similar reasons.
Many trees species (e.g. aspen, pines, birch) are shade-intolerant. In other words, they don't grow well or perhaps not at all in the shade of other trees. In nature these trees typically establish themselves only after all the other trees in an area have died or been blown down (for example, in a fire or windstorm). Aspen, for example, will actually sucker (resprout from the roots) after being cut. There is no way to regenerate aspen in the shade of other trees, therefore clearcutting is the best tool foresters use to regenerate this species.
Depending on when, where, and the scale of the clearcut takes place effect on the environment can be massive, especially in erosion-prone country if counter-measures are not taken. Production forests practicing monoculture reforestation techniques (plantations) often use this method of harvesting the timber. Experience world-wide has shown the need to preserve riparian strips on watercourses. Devoid of trees, many areas denuded in this fashion quickly deteriorate.
Clearfelling of oldgrowth forest continues on the island of Tasmania to supply the growing demand for paper pulp supplies in east asia. This is followed by an often severe loss of topsoil and a conversion of the land to industrialized monoculture plantations.
Good forestry always looks to the future. Bad forestry (more appropriately called bad logging since it really isn't forestry at all) is purely extractive in nature and does not look to the future.
Forestry in general seeks to balance the needs and wants of society within the context of economics and ecology as it pertains to forested landscapes.