Heritability and type B genetic correlation estimates for coastal douglas-fir in the US Pacific Northwest: trends and insights from 906 first-generation and second-cycle tests

ABSTRACT

Genetic parameters are reported for coastal Douglas-fir, from measurements on 24,000 first-generation open-pollinated families (786 test sites) and 2,400 second-cycle crosses (120 test sites) over a period of 45 years. The following were estimated: across-site narrow-sense individual heritability (h²_A), narrow-sense family mean heritability (h²_F), and type B genetic correlation (r_B), and_. narrow-sense single-site heritability (h²_w). The main traits were height, diameter at breast height (dbh), volume index (both cycles), and incidence of stem forking and ramicorn branching, upper stem sinuosity, and second flushing in the leader (second cycle). Smaller datasets were available for progression of budburst, straightness, needle retention, wood specific gravity and acoustic velocity. Measurements were between three and 30 years from planting. The dataset contained at least one trait measured for 2.602 million trees . Heritability (h²_A) estimates for height, dbh, volume and sinuosity ranged from 0.15 to 0.30, with a wider range for h²_w estimates. Heritabilities were higher in the second cycle. Forking and ramicorn branching had good h²_F heritabilities. Second flushing had high h²_A and r_B values; the same is often true for AV. Budburst was the most strongly inherited trait. h²_w for height, dbh, volume, forking and ramicorns was correlated with means for those traits.

KEYWORDS:

• Pseudotsuga menziesii
• heritability
• type-B correlation
• height
• diameter

Acknowledgements

This work was made possible by over 70 timberland-managing entities and their foresters who selected and climbed trees, collected open-pollinated seed, established seed orchards, made crosses, installed, maintained and measured first-generation and second-cycle test sites over more than 50 years. Comments by two reviewers were helpful in improving this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

These data are proprietary to members of the first-generation and second-cycle cooperatives who obtained the data, and are not available outside those cooperatives.

Additional information

Funding

Funding was provided by the Northwest Tree Improvement Cooperative.