Growth of natural Californian provenances of Pinus radiata in New South Wales, Australia.
Height and basal area data from a series of 8 provenance trials of Pinus radiata were analysed at age 8 yr. The trials tested 13 subpopulations from the 3 mainland California natural populations (4 from Año Nuevo, 6 from Monterey, and 3 from Cambria) as well as a single mixed-family seedlot from an first-generation unculled seed orchard at Tallaganda, NSW (composed of 30 clones of first-generation select trees from plantations in Australian Capital Territory (28) and Victoria (1), and New Zealand (1)). The test sites varied greatly in soil fertility and climate; mean tree height at age 8 yr ranged from 4.7 to 11.2 m. There were significant differences in growth rate between populations on several sites, and overall there was a large population × site interaction. Monterey was usually the best of the natural populations, but Año Nuevo grew better on the highest productivity sites and Cambria grew well on some low productivity sites. Despite the interaction, the seed orchard seedlot was the best population for growth at all sites. There was no evidence of subpopulation-within-population × site interaction, and in contrast to several previous studies, there were significant differences between subpopulations within some populations.