Improving Plantation Establishment by Optimizing Growth Capacity and Planting Time of Western Yellow Pines

摘要

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.