Improving planting stock quality - the Humboldt experience

A seedling testing program was developed to improve the survival and growth potential of planting stock produced in the USDA Forest Service Humboldt Nursery, situated on the Pacific Coast in northern California. Coastal and inland seed sources of Douglas-fir and eight other conifers in the Pacific Slope forests of western Oregon and northern California were assessed in both nursery and field studies. Seedling top and root growth capacities were evaluated just after lifting and after cold storage, and stored seedlings were tested for survival and growth on cleared planting sites in the seed zones of origin. Safe lifting and cold storage schedules were defined, and seedling cultural regimes were formulated to produce successful 1-0, 1-1, and 2-0 stock types. Testing demonstrated the critical elements of reforestation and proved that rapid establishment is attainable on diverse sites. Accomplishments of the Humboldt program recommend similar programs for other forest nurseries and their service regions.