Western Juniper Debarking Project

by Larry Swan, USDA Forest Service, Winema National Forest
from the Western Juniper Newsletter, Vol. 2, No. 1, Summer 1997.

The vast majority (approximately 80-90%) of western juniper trees are unsuitable for saw logs. Markets for fiber and other products must be pursued to economically harvest and process juniper on a large-scale. One potential market for juniper is as chips for hardboard. There is also some potential for chips to be used in medium-density fiberboard, especially if the oils have been extracted. Both products generally require a bark content of less than three percent.

The stringy and fibrous nature of western juniper bark, as well as log form, concern many in industry who have considered chipping juniper. A common belief is that juniper cannot be debarked effectively or efficiently with existing sawmill or "in-the-woods" debarkers. The purpose of this project was to gather information about the effectiveness and economic efficiency of commonly available debarking equipment on western juniper. This information will assist chip producers and sawmills analyze and select the most economical and efficient method for their particular operation and markets.

Three different types of debarkers were used in these trials: Ring, chain flail, and rosserhead. A total of about 90 logs were run through three ring debarkers at two different mills, about 10 logs were run through a chain flail, and about 19 logs were run through two different rosserheads at two different mills.

Contrary to common industry belief, all three types of debarkers performed effectively on juniper logs. Bark content of chips averaged below two percent, well within industry standards for such fiber products as hardboard and medium-density fiber board. Economic efficiency is another issue. If a mill does not already have a ring or rosserhead debarker installed, end-product market price range (such as chips) and costs of getting the product to market, must be closely examined. Portable mills probably will not be able to justify the capital investment for debarkers. For "in-the-woods" operations, chain flail debarkers also operate effectively and economically on western juniper.

For more information, contact Larry Swan, USDA Forest Service, Winema National Forest, 541-883-6714.

The full Western Juniper Debarking Project report is available on-line at http://juniper.orst.edu/debark.htm