Intra-Ring Variations in Mature Douglas-Fir Trees From Provenance Plantations

Variations in seven intra-ring characteristics were studied in juvenile and mature wood from two Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] genetic plantations. Samples were collected from 30 families representing 10 provenances with two replicates in each plantation. The following characteristics were determined by X-ray densitometry: earlywood density (EWD), latewood density (LWD), average ring density (RD), earlywood width (EWW), latewood width (LWW), total ring width (RW), and latewood proportion (LWP). Variation patterns were analyzed by two models: (1) families pooled across provenances and (2) provenances and families-within-provenances.Differences between plantations were significant for all traits except juvenile RD and mature RW and EWD. Variance components associated with families (pooled across provenances) remained the same with stand development and were biased upwards as a result of provenance variation. Genetic variation resulting from provenances was evident for RD and EWD, but (except for LWP) was relatively unimportant for RW parameters. Selection for families within populations can contribute to juvenile RW, as well as to mature RD and LWP