Dry weight partitioning among 36 open-pollinated red alder families

Six trees of each of 36 red alder (Alnus rubra Bong.) open-pollinated families were harvested from a genetic test plantation in September of the second field season and analyzed for growth and dry weight partitioning. Families from elevations greater than 300 m were significantly shorter than from those below 300 m and tended to be in intermediate or suppressed positions in the plantation canopy. Families from the most southerly drainage system, Santiam, were smaller than those from the more northerly drainages. When low elevation families (those from less than 300 m; 24 of the 36 families met this criterion) were analyzed separately, no statistically significant variation was found among the growth traits. In contrast, significant family variation was found in all of the dry weight partitioning traits and relative crown class. Family heritability (h²) values for low elevation families varied from 0·00 to 0·39 for growth traits and from 0·39 to 0·69 for dry weight partitioning traits. At this age and stage of plantation development, there seemed to be more variation in dry weight partitioning than growth of low elevation red alder families. Family means of the dry partitioning traits varied from as little as 5% to as much as 20% around the population means; hence, it appears that variation in some partitioning traits is large enough to be of practical significance in breeding and tree improvement programs.