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Cut-to-length Logging

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Forestry Processes

Cut-to-length logging (CTL) is a mechanized form of logging that involves the use of a harvester to fell, delimb, and buck timber, and a forwarder to transport the cut timber to a landing site. Also referred to as a shortwood operation, felled trees get cut at the stump and then processed and sorted inside the actual cutblock for different uses such as sawlogs, lathe logs, or pulpwood.

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[edit] Process

Cut-to-length logging is ideal for use in densely populated tree stands and on tree plantations. It is a relatively new form of tree harvesting that is more recognized in Europe, particularly in Scandinavian countries such as Finland where logging on tree plantations is common. In North America, full-tree logging has been more favorable and widely used, but this is slowly changing as the industry begins to realize the benefits presented by cut-to-length logging methods. For example, in the Lakes States region of the U.S., cut-to-length logging has been gaining popularity because many mills are able to process shorter logs. In comparison, mills in the southern U.S. are designed for processing wood from full-tree logging operations.[1] One reason for the rising use of cut-to-length logging in North America is its lighter ecological footprint. In some circles, cut-to-length logging has even been characterized as a low impact or gentle logging practice.[2] The method now accounts for 20 percent of the total volume of wood logged in Canada, east of Alberta.[3] The use of cut-to-length logging in isolated pockets of the U.S. and Canada is closely linked to mill requirements.

[edit] Cut-to-length Logging: A Snapshot

In cut-to-length logging, the log is usually cut 16 to 26 feet (5 to 8 m) above the stump.[4] Harvesters and forwarders are the two types of forest equipment associated with a cut-to-length logging operation. Harvesters are multi-functional felling machines that are tracked or wheeled and can maneuver right up to a tree. A rotating cutting head on a vertical axis affixed to the harvester via a telescopic pivoting boom arm is used to fell, delimb, and buck the tree into different-sized segments. This pivoting boom is highly flexible and capable of reaching in between trees to fell each tree individually with minimal damage to residual trees.[5] Once the tree is felled, the harvester positions the stem for bucking and delimbing. Some harvesters even come equipped with special processing heads that feed information to an on-board computer based system that calculates the approximate length stems should be cut into.[6] A forwarder travels behind the harvester to pick up and transport cut logs to a landing area where they are loaded onto logging trucks or a trailer for processing at a mill. Practically the entire tree trunk is used – only branches and crooked or un-marketable tree stems are left behind. This residual debris, called biomass or slash, is left on the ground to decompose.

[edit] Pros and Cons of Cut-to-length Logging

Compared to full-tree logging, cut-to-length logging has less environmental implications. One reason for this is that most operational activity in cut-to-length logging is isolated within the cutblock. Cut logs are lifted off the ground when transported to the landing site, resulting in less use of logging roads. Overall, site damage is greatly minimized and landing sites are often smaller.[7] In comparison, full-tree logging involves skidding or yarding logs to a landing site positioned at the roadside for sorting and processing. This involves the use of more logging roads and larger multiple landing sites. Dragging logs along the ground also disturbs the soil and increases the likelihood of soil erosion.[8]

One of the other environmental benefits of cut-to-length logging is that biomass or slash comprised of discarded stumpage and branches is dispersed throughout the cutblock after bucking and delimbing. This biomass creates a natural cushion or "travel mat" for harvesters and forwarders to work upon, especially when the ground is soft.[9] In addition, slash functions as a nutrient source for soil enrichment.[10]

Cut-to-length logging is also a highly flexible harvesting practice, since work can be carried out with low disturbance during wet periods and on steep slopes or terrain. As a result, a longer logging season is characteristic of this type of operation. In terms of adaptability, cut-to-length logging is a viable means of selective logging but can also be applied to most silvicultural systems and treatments including clearcutting, partial cutting, and thinning.[11]

Another advantage of cut-to-length logging is less handling of wood throughout the harvesting cycle, resulting in a better quality saw log product. Since wood breakage is kept to a minimum, the volume of mill production output greatly increases.[12]

Some of the drawbacks of CTL include a more expensive extraction phase than either full-tree or tree-length systems.[13] Harvesters and forwarders are quite expensive, costing anywhere between $100,000 to $200,000.[14] As a harvesting process, CTL is therefore limited to those areas where the benefits outweigh additional harvesting costs.[15] Comparable ground damage to that of full-tree or tree-length logging can also occur in operations that combine harvesters, skidders, forwarders, and loaders.

[edit] Equipment Used

[edit] References

  1. Forestry. John Deere. 2008-10-30.
  2. What is low-impact logging? West Virgina University. 2008-10-30.
  3. Harvesting Methods and Systems Defined. Dr. Reino Pulkki. Lakehead University, Faculty of Forestry. 2008-10-30.
  4. Harvesting Systems and Equipment in British Columbia. BC Ministry of Forests Forest Practices Branch. 2008-10-30.
  5. Cut to Length. Rothig Forest Products. 2008-10-30.
  6. What is low-impact logging? West Virginia University. 2008-10-30.
  7. Cut-To-Length. CTL Contractors Ltd. 2008-10-30.
  8. What is low-impact logging? West Virginia University. 2008-10-30.
  9. Harvesting Systems and Equipment in British Columbia. BC Ministry of Forests Forest Practices Branch. 2008-10-30.
  10. Cut To Length. Rothig Foresst Products. 2008-10-30.
  11. Harvesting Methods and Systems Defined. Dr.Reino Pulkki. Lakehead University, Faculty of Forestry. 2008-10-30.
  12. Cut-To-Length. CTL Contractors Ltd. 2008-10-30.
  13. Harvesting Systems and Equipment in British Columbia. BC Ministry of Forests and Forest Practices Branch. 2008-10-30.
  14. What is low-impact logging? West Virginia University. 2008-10-30.
  15. Harvesting Systems and Equipment in British Columbia. BC Ministry of Forests Forest Practices Branch. 2008-10-30.