Heli-logging

Tandem-rotor helicopter lifting a log

Heli-Logging, or Helicopter Logging, is a method of logging that uses helicopters to remove cut trees from forests by lifting them on cables attached to a helicopter.^[1] Helicopter logging is often used in inaccessible areas of forests. Because the use of helicopters reduces the level of infrastructure required to log in a specific location, the method also helps to reduce the environmental impact of logging. It also can increase the productivity in these remote areas.^[2]

History

Standing Stem Harvesting, a selective harvesting method within Heli Logging, was invented by Philip Jarman of Port Alberni, British Columbia between May and October 1997. The initial harvesting equipment used wire rope or chokers to rig the stem and a modified external hook to engage the choker and lift the stem clear of the stump. In this way the process of harvesting, which includes climbing, measuring, cutting, rigging, and lifting was pioneered by a single pilot flying a light utility helicopter. In 1998, the inventor supervised the building of an experimental grapple which was to be operated by a K-Max Lift Truck helicopter. However, because the K-Max had no hydraulics, it was necessary to design and install an externally mounted, jettisonable sled carrying a hydraulic power pack, to operate the grapple. Initial flight trials were carried out using the external hook and wire rope configuration on the 25th of April 1998. In late October 1998, a successful full scale harvesting trial using a grapple designed by the inventor and funded by the timber licensee was carried out at Lunchtime Lake on Vancouver Island.

Press releases and logging industry recognition followed. Patent applications in the United States and Canada were submitted and granted in 2001 and 2002 respectively.

Process

Heli-Logging is also known as standing stem harvesting which is based on individual tree selection (ITS).^[3] The selection process is done by engineers and surveyors. The trees are selected based on demand for specific types and grades. Before the selection process is complete the selected trees are bored to check their reliability. The selected trees are then marked and their diameters are recorded. The diameter of the tree is measured at 1.3 meters above the ground. The sizes of the trees that are selected are controlled by two things. The minimum size is controlled by the economy while the maximum size is controlled by the capacity of the helicopter. Once the trees are selected they are climbed, the limbs are removed and the trees are topped. The length of the tree and the diameter at its top are then recorded. All the recorded data is then entered into a database which calculates volumes, weights, etc. The selected trees are then partially cut at the stem and supported by wooden wedges. The stem is then grappled by the helicopter and pulled until the wood breaks at the partial cut. The logged trees are then brought by helicopter to a predetermined roadside location or dropped into open water where they are collected.^[3]

Advantages

Conventional logging allows the stems to fall. On rocky terrains this often results in damage to the stems that makes them unusable. On steep terrains falling trees can slide downhill and become irretrievable. Heli-logging allows logging to take place in more remote places. It also allows certain trees to be logged that previously could not be due to their proximity to a structure or pipeline. These issues make conventional logging less efficient than heli-logging. Logging using helicopters is safer than conventional logging. Falling trees are dangerous for the loggers as well as for surrounding structures or utilities. Heli-logging also extends the logging season. This is due to the lack of snow load on a standing stem.

Helicopters remove the branches and trunks as soon as they are cut. Because of this roads do not need to be built to the site were the logging is taking place. Fewer roads are built in the process and less heavy equipment is moved through the forest.

Research by Roberts, Ward and Rollerson done in 2004 shows that post-logging landslides are more common after conventional cable-based logging than heli-logging. Landslide rates following conventional logging are one and a half times more common than landslide rates following heli-logging.^[4]

Disadvantages

Although there is no direct cost from road construction or expansion, heli-logging incurs high costs. Operation of a helicopter as well as the selection processes and methods increase the cost. The use of a helicopter to transport the stems limits the size and weight of the selected trees more than equipment would using conventional logging.^[3]

References

1. Heli-Logging at Forestry.com
2. An Analysis of Utilizing Helicopter Logging in Turkish Forestry
3. Cleaver, D. 2001. Standing Stem Harvesting. The International Mountain Logging and 11th Pacific Northwest Skyline Symposium 2001, 280-284.
4. Roberts, B., Ward, B., & Rollerson, T. 2004. A comparison of landslide rates following helicopter and conventional cable-based clear-cut logging operations in the Southwest Coast Mountains of British Columbia. Geomorphology, 61, 337-346. Retrieved from Science Direct.