New Zealand Journal of Forestry (1981) 26(1): 70–80
©New Zealand Institute of Forestry
Twin- and single-rope gravity rollers - a site-preparation technique developed in New Zealand.
In New Zealand we have to look more seriously at steep scrub-covered hill country, much of it reverted farmland, for our steadily expanding afforestation programme. Manpower is not always readily available to prepare such land for a pre-planting burn. Techniques for the chemical desiccation of the vegetation are available but not preferred as the removal of all standing material is obviously a great advantage for manual planting.
Twin- and single-rope gravity rollers have been developed to overcome this land-preparation problem. Needing only minimal ridge-top tracking for the prime mover, these units come into their element on slopes greater than 25 degrees. With a controlled downslope reach of up to 250 m, contour tracking can often be avoided. The crusher-roller, up to 10 tonnes in weight, leaves the vegetation in a compacted, shattered, and quickly curing mass, ready for burning.
This paper discusses the development of this equipment, notes some specific characteristics of the existing units, the factors which contribute to productivity, and the advantages and disadvantages associated with their use.