Thinning of radiata pine by crawler tractor, on steep slopes in North-eastern Victoria: a preliminary study.  C. J. Leitch and G. B. Moore.  November 1981.  12 pp. (unpubl.)

SUMMARY

A study was carried out in north-eastern Victoria to investigate thinning of radiata pine (Pinus radiata D. Don) by crawler tractor on slopes in excess of 50% (26.5°). Machine productivity, damage to the retained trees and degree of site disturbance of a delayed first thinning operation were measured during five working days in August 1980, in an 18-year-old stand in the Merriang Plantation. The average daily productivity measured during the study was compared with those calculated from records obtained from operations on a range of slopes in the locality. In this study it was found that thinning steep terrain by crawler tractor was feasible, and there was no evidence that slope had a substantial effect on productivity. Skid trails constructed prior to the steep terrain study were not included in productivity calculations, though the cost of these trails was only 4% of the total cost of the operation. Further detailed studies, over a comprehensive range of slope classes and sites, are necessary in order to determine the effect of slope on productivity in this locality. During the steep terrain thinning study 17% of retain trees were damaged, though for P. radiata this may only cause a minor loss in value of the final crop. In the study area 25% of the soil surface was disturbed, however the combination of stable soils and frequent cross-drainage of skid trails should minimise the likelihood of significant soil erosion.

Also published:

Leitch, C.J. and Moore, G.B. (1981)  Thinning of radiata pine on steep terrain by crawler tractor in North-eastern Victoria.  I.U.F.R.O. Conf. on Econ. and Tech. of Thinning Plant. in Aust. and N.Z., Div. IV Thinning and Mech. - Econ. and Mech. of Harvesting Coniferous Plant., Canberra, Sept.-Oct. 1981, pp. 109-113.