Estimates of genetic parameters for growth traits and of effects of climatic transfer and edaphic conditions for select families New Brunswick black spruce

Abstract

The knowledge of genetic parameters estimate for black spruce in New Brunswick (NB) is limited. In this thesis, the estimates of genetic parameters for growth traits (bole volume, height, and diameter at breast height) and for stem forking (SF) in black spruce 35-year old family tests in NB are presented. These include heritability estimates (individual heritability and family mean heritability), type-B genetic correlation, age-age genetic correlation, and trait-trait genetic correlation. The growth of bole volume (V), tree height (HT) and diameter at breast height (DBH) are highly genetically controlled while SF is not. Type-B genetic correlations are moderately high for the growth traits, implying the weak environment × genetic interactions within the geographic region. Age-age genetic correlations are strong for the growth traits but weak for SF. Trait-trait genetic correlations for V and HT, as well as V and DBH are strong and positive, but are weak for V and SF. The potential effects of climatic transfer and of edaphic conditions on height growth of black spruce families are explored. Both the mean annual temperature and accumulated growing degree-days are important for height growth of black spruce in NB. Height growth is better on planting sites cooler than seed-source locations. Higher air temperatures resulting from changing climate will likely reduce black spruce height growth. Transfer difference in precipitation has little critical effect on height growth of black spruce from local NB sources planted in the province. In practice, temperature variable seems the most important climatic variable compared with other variables when deploying black spruce families. Transferring seed sources to relatively cooler sites will optimize height growth of black spruce in the province. Medium-rich soils of moderate moisture are the best for height growth of local black spruce in NB.