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Selective Cutting

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Forestry Processes
A Forest Landscape After Selective Felling
Selective cutting,
also known as selective felling, is a more ecologically sustainable practice than clearcutting. As a silviculture system it is designed to maintain an uneven or all-aged forest of trees varying not only in age, but in size and species as well.[1] The staggering of light cuttings in a forest stand as the trees grow and mature also lessens the ecological and visual impact harvesting has on a forest and provides an opportunity to create gaps in the forest canopy to encourage natural regeneration. Contrary to clearcutting, the selective harvesting of a timber stand is typically more expensive and produces less timber but is considered ideal for the harvesting and regeneration of shade tolerant species of trees.[2]

Contents

[edit] Process

In selective cutting, each tree must be individually assessed to determine whether it will be cut, left, measured, counted, or marked. The single most important factor used to determine what trees get harvested is economics. Other factors closely scrutinized include rate of growth, the potential for future growth, health and quality of a tree, spacing, and species type.[3]

Trees selected for harvesting are then cut at specific intervals. This process is referred to as a cutting cycle, meaning the trees cut are those one third or less than the maximum age of the oldest age class of tree within a stand. The trees harvested can either be individual trees scattered throughout the stand or small pockets of trees grouped together. Trees are spaced, thinned, or weeded in such a way that enough sunlight can reach ground level and allow for the natural regeneration of desired tree species to take place. Managing an uneven forest canopy as well as three distinct age classes of tree species within a stand is common of selective cutting.[4]

[edit] Pros and cons

Some of the advantages of selective cutting are: 

  • It supports more varieties of wildlife than clearcutting
  • It is more resistant to disease and insect manifestations than clearcutting
  • It leaves a lighter ecological footprint
  • It creates a more natural-looking forest stand after harvesting
  • At higher elevations and in northern forests, it encourages growth of desirable shade tolerant tree species

[edit] Types

Single tree selection is when new age classes of trees are introduced by the removal of individual trees of all size classes more or less uniformly throughout the stand. Sometimes this system is mistaken for high-grading partial cuts that harvest only the best and largest trees. A legitimate selection system, however, will always aim to improve and maintain the health and quality of a forest by removing the weakest and worse trees first.[5]

Group selection is when trees are removed in defined groups at a width no less than two times the height of adjacent mature trees. This system can be used for both even-aged and uneven-aged stands or for converting an even-aged stand to an uneven-aged stand.[6]

Strip selection is a modification of group selection in which narrow strips measuring a width of less than two times the height of adjacent maturing trees are progressively cut in long linear strips throughout the stand.[7]


[edit] References

  1. Selective Cutting. ACES Forestry Manual. 05-03-2009.
  2. Understanding Silviculture. Boreal Forest. 05-03-2009.
  3. Understanding Silviculture. Boreal Forest. 05-03-2009.
  4. Understanding Silviculture. Boreal Forest. 05-03-2009.
  5. Silvicultural Systems Guidebook. Government of British Columbia.05-03-2009.
  6. Silvicultural Systems Guidebook. Government of British Columbia.05-03-2009.
  7. Silvicultural Systems Guidebook. Government of British Columbia.05-03-2009.