Cone collection has become mechanized. Helicopters with aerial rakes collect large volumes of quality cones quickly and economically from the top of narrow trees.

Manual cone collecting has disadvantages. As some cones ripen quickly and seeds scatter abruptly, harvesting windows are only open briefly. Cone collectors sometimes have to trudge through underbrush as thick as stalks in a corn field or squish through swamp water or climb dangerous heights to reach elusive cones, in some species clustered within 3 feet of a flimsy top. When their cone cache is being robbed, squirrels often plead for their winter food supply, unsuccessfully. Felling trees for cones requires co-ordination with logging operations.

Aerial rakes permit foresters to collect large volumes of cones during heavy crop years when the yields are higher, the costs are lower and the quality is better. To better the quality of the cones, to improve the reliability of the seedlings and to increase the rate of future tree growth, foresters can select cones by specifying elevations, locations and types of trees. During heavy crops many species of trees can be harvested more economically from the air than from the ground.

Aerial harvesting requires diligent project planning and constant cone monitoring to be cost effective. If the crop is not closely surveyed or the quality of cones is not carefully monitored or the collecting rate is not closely watched, aerial collecting can be expensive.

Canadian engineer Helmut Fandrich and helicopter pilot Fred Fandrich invented the Fandrich aerial cone rake in 1979. The pilot lowers the aerial rake over a tree so that 15-20 feet of the top emerges through the center opening. As the pilot raises the rake, the cone-laden branches fall into a basket surrounding the cutting head. After raking 5-10 trees, the pilot dumps the load at a convenient unloading site for sacking.

Aerial raking gained popularity quickly. Hedin (1983) summarized the 1982 Ministry of Forests cone collection reports and found that 64% of all the cones collected in the Vancouver Forest Region of British Columbia were collected with aerial rakes, 17.5% were collected by felling trees, 11% were collected by climbing and 7.5% were collected by aerial topping (leaning out of the back seat of the helicopter and cutting tree-tops with hydraulic clippers or chain saws).

Aerial collecting rates depend on tree species, cone density and raking techniques in addition to many other factors as shown on the table. Improvements in rake design helped increase the average collecting rate for true fir (eg. Abies amabilis) from 16 bushels per hour in 1979 to 60 bushels per hour in 1983 (data supplied by harvesting companies).

The volume of cones harvested can be impressive. Rau (1982) reported that in one day an aerial rake collected 319 bushels of Pacific silver fir (Abies amabilis) cones at $17.60 per bushel and 17 bushels of western hemlock (Tsuga heterophylla) cones at a cost of $125.60 per bushel. In 1983, a rake collected 480 bushels of grand fir (Abies grandis) in one day at a rate of 81 bushels per hour. In 1985, one thousand bushels of Redwood cones were collected in California at 26 bushels per hour, and a small quantity of larch cones were collected in Montana from a mediocre crop at 6 bushels per hour.

Cones collected aerially yield more seeds per bushel with higher germination rates than cones collected from the ground. Cornell (1985) reports the yield from 1226 bushels of white fir cones collected aerially in the Stanislaus National Forest in California was 2.4 times higher than is usually obtained from seed collected manually. The germination rate for the aerial collection was 60%, well above the average, and the cost of seed was just over $36 per pound compared with $69 per pound for past collections, (Durham, 1985).

The aerial rake leaves the tree-top intact so the `pruned' trees usually continue growing and sometimes produce large `stress' crops. More data is needed on how trees respond to aerial raking.

Fandrich aerial rakes ushered in the age of mechanized cone harvesting. Today's foresters benefit by collecting large volumes of quality cones quickly. Future generations will benefit by having faster growing superior trees.

LITERATURE CITED:

Hedin, I.B. 1983. "Aerial Cone Collection Techniques in British Columbia". Technical Note No. TN-69. Forest Engineering Research Institute of Canada, Vancouver, BC. 55 p.

Rau, Clyde. 1982. "An evaluation of Aerial Cone Harvesting on the Shelton Ranger District, Olympic National Forest, September 22 and 23, 1982". US Department of Agriculture, Forest Service, Shelton, WA. 3 p.

Cornell, Blaine L. 1985. "Appraisal Fandrich Cone Rake - Stanislaus NF", United States Dept of Agriculture, Forest Service, Stanislaus National Forest, December 18, 1984 & March 1, 1985. 12 p. & 2 p.

Durham, Rose Marie & Wurm, Duncan C. 1985. "Cones by Copter", American Forests, Washington DC, November 1985, 3 p.

Bray, B. & McLean, H. 1982. "Operational Trials of the Fandrich Branch Collectors". Ontario Ministry of Natural Resources, Northern Region, Timmons, ON. 37 p.