In Forestry
Thinning in forestry is the selective removal of trees, primarily undertaken to improve the growth rate or health of the remaining trees. This may be done to make the stand more profitable in an upcoming final felling. Overcrowded trees are under competitive stress from their neighbors. Thinning may be done to increase the resistance of the stand to environmental stress such as drought, insect infestation or extreme temperature.
A thinning in which the trees removed have little or no economic value is called a pre-commercial thinning. Ecological Thinning is a variant of this being trialled for use in forest conservation in Australia. Chemical thinning is a form of non-commercial thinning in which the trees are killed while they stand by injecting a chemical such as glyphosate (Round Up) into a cut made in the stem. This reduces the number of live stems remaining, providing a benefit to those that remain and may be undertaken where the cost of a traditional thin is high. It can also be done on very exposed sites where breaking the canopy through a traditional thinning operation would expose the stand to a high risk of windthrow.
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