GENETIC-VARIATION AND SEED ZONES OF DOUGLAS-FIR IN THE SISKIYOU NATIONAL FOREST

Provisional seed zones and breeding zones were developed for Douglas-f ir (Pseudotsuga menziesii (Mirb.) Franco) in the Siskiyou National For est in southwestern Oregon. Zones were based on maps of genetic variat ion patterns obtained by evaluating genotypes of trees from 260 locati ons in the region. Genotypes controlling growth vigor and growth rhyth m were assessed in a common garden. Within the Forest, three breeding blocks were recommended, with different numbers of elevational bands i n each block: from 0 to 610 meters, from 611 to 838 meters, and then a series of bands 152 meters wide at higher elevations.