Effects of site, provenance, and provenance and site interaction in sitka spruce in coastal British Columbia

Journal Article

Transfer Guideline: Recommendation

The IUFRO International Sitka spruce (Picea sitchensis ) provenance experiments were planted at eight sites in Coastal British Columbia in 1975. The tests were planted in two series, with four sites in each series and 10 provenances at each test. A total of 14 provenances were tested with 6 provenances common to both series. Total height and survival were recorded at 3: 6, 10, 15 and 20 years after planting, and diameter at ages 10, 15 and 20 at most tests. Test sites accounted for about two-thirds of the total variation. Size of provenance variance components was different between the two site series. Interaction between provenance and site was high and statistically significant in both series. Site climate and attack by the white pine weevil (Pissodes strobi ) were the major determinants of site productivity and also the main causes of the interactions. Latitudinal pattern in provenance variation was eminent at most sites at early ages and maintained throughout at sites with strong maritime climate and free of weevil attack; at harsh northern and inland sites, geographic pattern of provenance variation shifted toward longitudinal (coast - inland) at later ages, and the harsher the site environment the earlier the shift. Practical implication in terms of seed transfer of the fast growing southern coastal sources and weevil resistant provenances in reforestation in coastal British Columbia was discussed.