West Coast Tree Improvement Programs

Three tree improvement programs were analyzed by break-even, cost-benefit technique: one for ponderosa pine in the Pacific Northwest, and two for Douglas-fir in the Pacific Northwest-one of low intensity and the other of high intensity. A return of 8 percent on investment appears feasible by using short rotations or by accompanying tree improvement with thinning. Interest rates, length of rotation, the inclusion of thinnings, and site index had greater effects on profitability than program design. Large breeding zones improved profitability, although they incur the biological risks of nonadaptation to local conditions and loss of local genetic resources. Increasing orchard seed yield affected the results only slightly unless the planting program could be expanded, which is equivalent to increasing the size of the breeding zone. If the increase in seed yield merely reduced the required acreage of seed orchard and associated costs, the financial results improved only slightly.

In a 1964-1967 study on the Challenge Experimental Forest, seedfall was evaluated in 2-, 5-, and 10-acre circular clearcuttings. During the 4 years, 10 seed crops, ranging from light to bumper, were produced by ponderosa pine. white fir, Douglas-fir, and incense cedar. Seedfall ranged from 76 to 40,691 sound seed per acre (188 to 100,547/ha) for a single species in a given year. From 89 to 100 percent of each species' seed fell within an area 1 1/2 times the height of the average dominant tree. Overall, seed distribution was highly variable.

This handbook was designed as a reference tool for forest geneticists, tree breeders and other tree improvement personnel, as well as a textbook for university courses and short-courses at the graduate level in quantitative genetics. The chapters focus on the decision points faced by quantitative geneticists and breeders in designing programs and analyzing data. Beginning with a justification for the use of quantitative genetics in decision making in tree improvement programs, the book continues with a brief presentation of fundamental principles, followed by discussions and evaluations of mating designs and field test designs, the use of best linear predictors to estimate breeding values, the use of computer programs in the analysis of variance for genetic information, the deployment of genetically improved stock for capturing gains, the use of economic models for program justification, and the development of seed transfer guidelines.