From my research... partial shade is good for the first few years of life. I read a study (trying to find it) that indicated higher success rates in partial shade than in straight sun. I'll try to find that article for confirmation.
EDIT: Here the article I read. It's not a cut-and-dry answer for you. It suggests that there is more water and less herbivory in shade. I give mine seedlings that I grew from acorns this year partial shade and they seem to be doing well.
Go to this section: "
Seedling establishment/growth:"
Because of drought and herbivory's deleterious effects on seedling survival, recruitment is best among germinants growing in shade, where herbivory protection and water availability are higher [157]. Recruitment among rock outcrops is relatively common as this offers some protection from large browsers [66]. Common nurse plants are California heathgoldenrod (Ericameria ericoides), chamise, coyote bush (Baccharis pilularis), purple sage (Salvia leucophylla), orange bush monkeyflower (Diplacus aurantiacus ssp. aurantiacus), chamisso bush lupine (Lupinus chamissonis), California sagebrush (Artemisia californica) and poison-oak (Toxicodendron diversilobum) [28,118]. Eighty percent of seedlings found on sites in the Santa Ynez Valley of Santa Barbara County were growing under purple sage or California sagebrush. Another 15% grew under mature coast live oak. Mortality due to herbivory was considerably higher among seedlings under parent trees [28]. Establishment is generally greater in coastal sage scrub than in other types of chaparral [30]. A study of coast live oak seedling establishment, with and without nurse shrubs and cages for protection, found that acorns planted in the open had higher germination but lower 1-year survival. Between 1 and 2 years of age, nurse shrubs had no effect on seedling survival, but cages continued to have a positive effect by reducing black-tailed deer browsing [118]. Another study of coast live oak establishment at 2 sites in central California showed strong association of seedlings with shrubs. Shrub cover was 30%, but 80% of coast live oak seedlings were under canopies. In 2 years of monitored growth, survivorship was 0% in open areas and 31% under shrubs. Seedlings in the open were grazed more, but drought also increased stress. Mortality related to moisture and temperature stress was 17% under shrubs and 63% in the open. The authors noted that differential dispersal might also increase recruitment under shrubs [28].
