An investigation of the monocable system for cable yarding of small, low-value trees on steep, difficult sites.

摘要

About 70 percent of the commercial forestland in the western part of the Pacific Northwest contains second-growth timber stands. Thinning is currently necessary on 25 percent of this land for future stand rigor and value. Approximately 14 million tons of forest residues, such as dead or dying trees, tops, and limbs, accumulate each year in the United States. If these vast quantities of small, low-value trees can be recovered and used through thinning operations and forest residues, the following benefits can be expected: (1) Reduction of fire, insect, and other environmental problems. (2) Reduced reliance on petroleum imports. The energy potential of the 3.3 billion cubic feet of logging residues of pieces 4 inches and larger in diameter annually remaining in the forests of the United States is roughly equivalent to 100 million barrels of oil. (3) Improvement of aesthetics and future management capability for timber quality and value, soil and water quality, fish and wildlife habitat, and air quality.; Operations in low-value young stands and harvesting large amounts of forest residues are presently limited because of the lack of economically efficient and environmentally acceptable equipment and systems to transport the materials to the landing under adverse working conditions. Steep slopes, fragile soils, limited road systems, and scattered low-value stands contribute to adverse working conditions.; A yarding system that uses a unique monocable concept was investigated to help solve the problem in the Pacific Northwest and other mountainous areas in the United States. This dissertation presents results of a series of engineering research to determine the following operational characteristics of the monocable system: (1) Low initial cost; (2) Low hourly machine rate; (3) Low fuel consumption (0.2-0.4 gallons per hour); (4) High (Up to 2,500 feet) of yarding capability; (5) No limitation by degree of ground slope; (6) High capability of transporting small trees by precommercial and commercial thinning operations without damaging the standing residual trees; (7) High flexibility for the changing geometry of topography and terrain; (8) A productivity equal to or better than the existing small yarding equipment and systems in the United States; (9) High ability to meet environmental constraints.