Improving Plantation Establishment By Optimizing Growth Capacity And Planting Time Of Western Yellow Pines

Seedlings of 27 sources of western yellow pines, selected in climates typical of the species, were raised in a nursery in the western Sierra Nevada. Seedling top and root growth capacities were periodically assessed during fall and winter, and field survivals of outplanted seedlings were evaluated in different climates with summer drought. In the nursery, four distinct, innate seasonal patterns of root growth capacity were defined in ponderosa pine from within and outside California, and two distinct patterns were defined in Jeffrey pine. Below snow line in the western Sierra Nevada, seedling survivals were higher in spring plantings than in a winter one, and for California sources than for others. In spring plantings above snow line, survivals for diverse local sources of ponderosa and Jeffrey pines were uniformly high, both on the western slope and east of the Sierra Nevada crest. The results demonstrate that seedlings of any source will have adequate growth capacity and will survive the first year on any well prepared site if they are lifted at the right time, stored properly, and planted in phase with warming soil trends.

A trial of 36 species of Eucalyptus near Concord, California, found species of sufficiently rapid growth and good survival to merit further screening. Species from western Australia and of the subgenus Monocalyptus all failed on the site. E. camaldulensis, E. dalrympleana, E. glaucescens, E. grandis, E. nitens, E. ovata, and E. viminalis were the species with best survival and growth.

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.

Evaluates seedling top and root growth capacities just after lifting and after cold storage. Defines safe lifting and cold storage schedules and seedling cultural regimes as critical elements of reforestation. Proves that rapid establishment is attainable on diverse sites. 28 graphs, tables and photos.