Compacting cohesive soils for forest roads is relatively inexpensive ($500 to $1000 per km) and cost-effective, yet compaction still isn't used extensively by the forest industry. Increased soil density reduces settlement, increases soil strength, improves bearing capacity, limits volume changes and often leads to lower construction and maintenance costs. These savings often cover the cost of compaction. FERIC recently studied the impact of soil compaction in two road construction techniques: V-ditch embankment (in which density increased by 8% and penetration resistance tripled) and the lift-over rootmat method (in which density increased little and penetration resistance doubled).
The Mountain Alternative Silvicultural Systems (MASS) study is a multi-disciplinary, multi-agency project initiated both for silvicultural and social reasons. MacMillan Bloedel Limited, the Canadian Forest Service, and FERIC cooperated in the study, with participation by the University of Victoria and the University of British Columbia. Three alternative treatments representing a range of canopy removal levels - uniform shelterwood, green tree retention, and patch cutting - were implemented in the research area, located on the east coast of Vancouver Island. FERIC monitored the productivity and cost of the falling and forwarding operations, and measured site disturbance and coarse woody debris for each harvesting treatment. The results of FERIC's study are presented.
From July to September 1997, FERIC performed short-term case studies of five different implements used to till compacted landings in the Cariboo Forest Region. The case studies were part of a larger study by Lignum Ltd. and the B.C. Ministry of Forests, Cariboo Forest Region to investigate techniques for rehabiliting compacted medium and fine-textured soils. The five implements studied were: an excavator-mounted six-toothed silvicultural rake; a rake and a high-speed mixing head mounted on skid-steer loader; a Tilth winged subsoiler towed by a crawler tractor; standard ripper teeth mounted on a crawler tractor; and a skidder-mounted powered disc trencher. This report reviews the treatments, productivities and costs of using the five implements.
FERIC studied the impact of the use of ghost trails by a feller-buncher on the soil and on advance regeneration. Under the study conditions, the results indicated minimal soil disturbance in the ghost trails and a normal reduction in stocking for such an operation. Given that the productivity of the operation with ghost trails was comparable to that of a conventional operation, this approach appears promising.
In Canadian boreal forests, harvesting with protection of advance regeneration requires the creation of an intensively used network of skid trails. In this context, the effects of repeated skidder passes on soils were studied in terms of rut depth, the amount of displaced material in the trails, and soil bulks density. Two types of soil were studied: sands and clays. The factors that helped to explain the observed amount of soil disturbance were the number of skidder passes, the amount of wheel slippage, soil density, the soil's penetration resistance, and the soil's shear resistance. The results of the study indicated that the effects of skidder traffic on soil properties stabilized after a few skidder passes on sands, whereas the effects on clay soils continued to increase with an increasing number of skidder passes.
This report was prepared under the auspices of the ENFOR (Energy from the Forest) Program of the Canadian Forestry Service. It investigated compaction as an addition to comminution, or as an alternative to comminution, as a practical and economical means for handling transporting and processing logging residues so that they can become a greater source of energy in Canada.
The relationship between the forest, the soil and the harvesting equipment must be understood if forest companies are to achieve sustainable and environmentally acceptable forest practices. As the soil is both the pavement over which harvesting and site preparation equipment must travel and the growing medium for future harvests, the forest industry must understand the impact of equipment activity on future fibre supply. To provide information on the interaction between forest equipment and the soils, FERIC organized a workshop for forest operations and agency staff, and contractors. More than 80 people attended the workshop that was held in Whitecourt, Alberta on February 26th, 1999. The focus of the presentations was to provide the audience with information and basic soil properties, soil mechanics and vehicle dynamics, and the effects of compaction on soil physical properties. In addition, other presentations included summaries of studies undertaken in western Canada on the impacts of felling and skidding equipment on forest soils, and impacts of harvesting activities and deciduous and coniferous regeneration. Finally, management strategies for minimizing soil degradation were discussed. These Proceedings summarize the presentations during the workshop.
The Forest Engineering Research Institute of Canada (FERIC) monitored a summer roadside harvesting operation in a hardwood-dominated stand near Dawson Creek in northeastern British Columbia. This report presents the productivity and cost of the harvesting operation and describes the soil disturbance from skidding and loader-forwarding.
Cut-to-length harvesting with a Timberjack harvester and forwarder was studied in patch cut, partial cut, and clearcut harvesting blocks in southern B.C. from 1996 to 1999. The harvesting treatments were prescribed to salvage tree mortality form insect attack and windthrow. This study documented operational logistics, cost and productivity of harvesting, residual tree damage, slash loading, and change in soil surface condition.