Forest Harvesting

FOREST harvesting refers to the process of cutting TREES and delivering them from the forest to sawmills, pulp mills and other wood-products-processing plants. It includes forest engineering, forest-road construction, logging and log transportation.

Forest engineering is the field of ENGINEERING that specializes in planning forest harvesting. A forest engineer working in naturally grown forests must plan and locate permanent roads that meet the long-term goals of forest management and which may later become public-access ROADS AND HIGHWAYS. The logging system that best meets environmental and financial objectives must be chosen; branch-road networks planned; road construction supervised; and logging machines selected.

A forest engineer requires knowledge of the principles of FORESTRY, SURVEYING, GEOLOGY and SOIL SCIENCE, and familiarity with available machinery. When developing a harvesting plan, the engineer starts with a long-term forest management plan, usually prepared by government and industrial foresters in consultation with specialists in fish and wildlife habitat, recreation, water and soil quality. This plan shows the timber area to be cut, the proposed rate of cutting and the special requirements of other forest users.

Forest-Road Construction
The Canadian forest industry builds approximately 15 000 km of logging roads each year. Half of those are temporary winter snow roads and unsurfaced summer roads. All of these roads require planning and surveying. They must be constructed to minimize erosion, protect water quality and cause the least impact on the forest growing site. Permanent roads must be surfaced for all-weather traffic and the bridges, culverts and ditches must be adequate to withstand major storms without constant maintenance. In BRITISH COLUMBIA temporary roads are rehabilitated after harvesting so that the forest site is available for growing trees. This also reduces the requirement for road maintenance and the risk of future erosion.

Bulldozers are used to build roads in dry and sandy soils, while backhoes are used in the wetlands of the boreal forest. On the BC coast, roads are expensive to construct because of the rock encountered in the mountains. Backhoes pioneer the subgrade and rock is drilled and blasted. On steep slopes blasted rock must be end-hauled back along the road to a place where it will not slide and cause erosion or damage fish-bearing streams.

Logging
Cutting methods include progressive clear-cutting, patch cutting and individual tree selection. Clear-cutting is commonly practised in natural, undeveloped forests. It requires the least initial road construction, permits loggers to concentrate their operations and enables foresters systematically to prepare sites and engage in REFORESTATION after cutting. Large cutover areas, however, are unpopular with the public. Logging scattered patches requires more initial road construction and exposes more fringe trees to wind damage. Patch-cutting is normally used for harvesting successive crops from a planted forest. Individual tree selection is used to thin an overstocked immature forest, to cut hardwood or other species which grow in shade, and to retain the cover along streams and on dry south-facing areas exposed to the direct sun.

The word "logging" may refer to all harvesting operations or may apply only to the stump-to-roadside activities.

Felling

Hand-held chainsaws are commonly used for felling (or falling) trees. The faller uses an undercut and wedges to control the direction of fall. Felling is dangerous and requires skill, especially if trees are large, partly rotten or have intertwined branches. Mechanical felling machines using chainsaws or circular saws mounted on tractors or excavators are used to fell trees up to 80 cm in diameter. Multi-function tree harvest machines are used in stands of small trees. They cut, limb and top the trees and move them to the roadside, or may perform any combination of these functions. Mechanical felling is safer than chainsaw felling but the machines are expensive and operate best where large numbers of trees can be cut in one location.

Skidding
Skidding involves dragging logs or trees to the roadside with a horse, wheel skidder or tractor. Horses and farm tractors are used on small private woodlots, but articulated, centre-steering wheel skidders (developed in Canada in the 1950s) are used on most operations. A faller with a hand-held chainsaw and a skidder operator often operate as a team: they log "hot," ie, skid each tree soon after it is cut. If mechanical cutters are used, the trees are felled days or weeks before skidding. Trees felled and bunched with a feller buncher are often skidded with a grapple skidder which can pick up the complete bunch. Crawler tractors with bulldozer blades are used for skidding on steep ground where trails are required.

Yarding
Yarding is the dragging of logs from stump to roadside using cables and yarders (winches). The most common methods are high-lead, in which logs are lifted at one end and dragged across the ground, and skyline, in which the log is transported wholly through the air. Normal yarding distances are up to 300 m, but special systems can yard at distances of 500 m and, in some cases, 700 m. Helicopters are used for logging valuable timber from places inaccessible by road or where roads would cause damage.

Processing and Sorting
Processing and sorting involves removing the limbs and tops from the trees, cutting them into merchantable log lengths and sorting them by grade and species so that each log goes to the particular mill that can recover the maximum value from it. Limbing and bucking may be done at the stump after the tree is felled, or at the landing with specialized machines. Sorting takes place at the woods landing, at the transfer point from trucks to secondary transportation, or at the mills. Front-end loaders, log stackers and cranes are used. Frequent communication between the forest operations and the mills is necessary to ensure that logs are cut to the correct length and go to the right mill.

Log Transportation
Most trees harvested in Canada are transported by truck. Front-end loaders, cranes and special loaders load trucks in the landings. Pulpwood is often hauled crossways on flat-deck semitrailers; in BC and ALBERTA long logs are hauled on pole trailers. Many new truck and trailed configurations have been developed to permit the safe hauling of maximum loads and comply with the highway regulations.

Water transport is a common form of secondary log transport on lakes and rivers and on the Pacific coast. Most river drives in eastern Canada have been eliminated because of environmental concerns and log losses through sinkage. On the BC coast, logs are transported by truck to the water and then formed into RAFTS of log bundles for transport to mills. Bundling logs reduces losses from sinkage and escape. Logs from HAIDA GWAII and the west coast of VANCOUVER ISLAND are transported through rough seas on barges and log ships. Water transport is cheap and is the only method of transporting logs from isolated islands or coastal inlets. The forest industry in BC supports a large secondary industry of tugs and barges, which move not only logs but pulp, pulp chips, lumber and other products.

Forest Products
Canadas forests produce a large variety of commercial products, and Canada is the worlds leading exporter of lumber, pulp and newsprint. Higher-grade BIRCH, MAPLE, OAK, DOUGLAS FIR and Sitka SPRUCE are manufactured into expensive veneers and finished lumber. White spruce, western HEMLOCK and lodgepole PINE are used for construction lumber and plywood; black spruce, jack pine hemlock and ASPEN are excellent for newsprint. Lower grades of all species are made into pulp. Sawmills are being improved to produce better and more valuable products and to recover more fibre from each log. Small pieces of wood are finger-jointed and spliced or laminated into timbers using improved glues. Sawdust and low quality wood not suitable for pulp are made into composite panel boards. The manufacture and sale of forest products in Canada is highly integrated and specialized to ensure that each tree is cut into the most valuable product. In this way, Canada can conserve its remaining stands of quality trees and derive the maximum benefits from the forests.

Author G.V. WELLBURN

Links to Other Sites
International Year of Forests, 2011
The United Nations website for the International Year of Forests. 2011. Check out the calendar of international events and the latest news about the International Forest Film Festival.

The Forest Products Association of Canada
FPAC represents Canada’s wood, pulp, and paper producers nationally and internationally in government, trade, and environmental affairs. Their website offers background information about economic and sustainability issues related to their industry.

Natural Resources
An extensive collection of photographs about Canada’s natural resource industries, including forestry, energy, and mining. Part of the CN Images of Canada Gallery at the Canada Science and Technology Museum website.

Canadian Boreal Initiative
The Canadian Boreal Initiative is working with a wide range of conservation organizations, First Nations, industry and other interested parties to link science, policy and conservation activities in Canada's boreal forest.

Overview of Quebec's Forests
This website focuses on the economic and environmental issues related to the management of Québec's extensive forestry resources. Features a great selection of links to related websites.

Upper Canada Woods Cooperative
The Upper Canada Woods Cooperative is a forest landowner management, processing and marketing co-op that promotes sustainable, environmentally responsible forest practices, landowner and consumer education, and local manufacturing of value-added products.

borealforest.org
This site offers descriptions of mammals, birds, amphibians and reptiles, fish, and plant life found in boreal forest regions. Also includes a glossary of terms related to forestry.

Glossary: Logging and Lumbering
This glossary defines terms related to logging and lumbering operations. From the website for Past Forward Heritage Limited.

Glossary: Logging Operations
Definitions of terms related to conservation and logging operations on private land in alberta. A Government of Alberta website.

Logging in Saskatchewan
This teachers guide chronicles the colourful history of the lumber industry in Saskatchewan. From the Western Development Museum.