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Silviculture Systems
......Extracting and replacing a living resource

Teacher Background - Part 3

Selection of the correct system minimizes
environmental impacts and permits a wide range of resource values
(multi-use or integrated forest management)

#1. CLEARCUTTING

  • the removal of all trees over an area of one hectare or more in a single harvest
  • variations of clearcutting include: clearcutting with reserves (some trees left in the cutblock to provide wildlife habitat and aesthetic value): patch cutting - small opening less and 1 hectare in size is cut
  • the size of clearcut patches has been reduced dramatically today - the large ones are usually due to an area that has bug kill or some other forest health problem (fire, disease)
  • certain species are candidates for clearcutting - for example, Lodgepole Pine trees need direct sunlight for regeneration - this species does not grow very large and the root system is rather shallow, so if there is too much space left between remaining trees, they often blow down
  • this type of harvesting is often done in an even-aged stand of trees (all of the trees are the same age)
  • this is the simplest and most economical method
  • the even-aged stand would be replanted or would regenerate naturally

#2. SEED TREE

  • small groups of trees or individual trees are left standing to provide a seed source for new growth (these would be hardy, healthy trees)
  • the largest and healthiest trees are left in the cutblock to provide high quality seeds for the next generation
  • the seed trees would be left until the next generation of trees is ready to be harvested - they would then be cut down or left to provide for wildlife habitat and aesthetic value
  • the even-aged stand would eventually return either naturally or by reforesting

#3. SHELTERWOOD

  • some mature trees are left standing to provide shelter (protection) for a new even-aged forest that will grow under them
  • once the new generation of trees is ready to be harvested, these shelterwood trees may be cut down or left for biological diversity, wildlife habitat or aesthetic value
  • more expensive than clearcutting

#4. SELECTION

  • creates an uneven-aged stand of trees by harvesting a limited number of trees of various sizes and ages, over time
  • mature and immature trees are harvested individually or in groups
  • doesn't often apply to many of the province's ecosystems and tree species
  • more expensive to do

FOR FURTHER DEVELOPMENT OR FOR INFORMATION

#1. See brochure in this package entitled "Silviculture Systems in British Columbia" - this brochure outlines advantages and disadvantages of all systems and provides some additional background information

#2. Contact a local forest company or the Ministry of Forests and Range office and request a classroom speaker to visit and to make a presentation on Forest Management - have students prepare questions ahead of time for your guest.

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