Tree shaking machine aids cone collection in a Douglas-fir seed orchard.

Abstract

A boom-type tree shaker was used in a Douglas-fir seed orchard to remove cones from 7- to 9-meter tall grafted Douglas-fir trees. An average of 55 percent of the cones were removed by shaking, while damage inflicted to the upper crown was confined primarily to branch and leader breakage in the top three internodes. Damage to the lower bole, where the shaker head attached to the tree, occurred only once. Shaking a significantly greater proportion of cones from 7- to 9-m tall Douglas-fir trees without drastically increasing top damage is not likely. Much of the cone crop on small trees is found on the difficult-to-shake lower half of the trees; energy levels sufficient to remove those cones would cause severe breakage in the upper crown. The shaking procedures outlined in this report were relatively gentle, yet they resulted in the harvest of over half the cone crop in a rapid and efficient manner. It should be possible to machine-harvest cones from approximately one tree per minute when a tree shaker and mechanical catch frame are used in seed orchards that have cones on a majority of the trees. Handpicking the cones remaining on the trees after shaking will still be necessary, but that job should be much easier than picking cones from unshaken trees; more than half the cones will have already been removed, including most of the difficult-to-reach cones from high in the trees. A combination of machine harvesting and hand picking of cones should considerably shorten the time required to complete the cone harvest and the cost per bushel should be reduced because of increased efficiency.

Citation

Copes, Donald L.; Randall, William K. 1983. Tree shaking machine aids cone collection in a Douglas-fir seed orchard. Res. Note PNW-RN-406. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 7 p