Genetic variation in the diameter–height relationship in Scots pine (Pinus sylvestris)

Abstract

Genetic parameters were estimated for the diameter-height (d-h) relationship and three other tree stem-form characteristics (total height, breast height diameter, and total tree volume) for data from 10 diallel progeny trials of Scots pine (Pinus sylvestris L.), at about 30 years of age in Sweden. Linear mixed models were fit to the data, where adjustments for intertree competition and microsite heterogeneity were made by means of covariates in a nearest-neighbour analysis. The d-h relationship was analyzed with a covariate (tree height) adjusted model of diameter. Average estimates of the additive coefficient of variation and narrow-sense heritability for the d-h relationship were 7.4% and 0.22, respectively. Estimates of dominance were comparatively small (average dominance: phenotypic variance ratio of 0.04). The results indicate that there is scope to modify the d-h relationship by selection and breeding. Additive genetic correlations between the d-h relationship and height were negative, with a mean of -0.62. Selection for height would thus result in stems that are more slender than average, suggesting that tall trees allocate relatively more resources to height growth than to diameter growth. Selection based on height alone will negatively affect volume gain. Résumé :Les auteurs ont estimé les paramètres génétiques de la relation entre le diamètre et la hauteur (d-h) des arbres et de trois autres caractères de forme de la tige (hauteur totale, diamètre à hauteur de poitrine et le volume total de l'arbre) à partir des données de 10 tests de descendances diallèles de pin sylvestre (Pinus sylvestris L.) âgé d'environ 30 ans en Suède. Des modèles linéaires mixtes ont été ajustés aux données, incluant des ajustements pour la compétition entre les arbres et l'hétérogénéité des microsites effectués au moyen de covariables dans une analyse du plus proche voisin. La relation d-h a été analysée à l'aide d'un modèle de diamètre ajusté pour une covariable (la hauteur de l'arbre). Les estimations moyennes du coefficient de variation additive et de l'héritabilité au sens strict pour la relation d-h affichaient des valeurs respectives de 7,4 % et 0,22. Les estimations de dominance étaient comparativement faibles (le rapport moyen de la variance de dominance sur la variance phénotypique était de 0,04). Les résultats indiquent qu'il est possible de modifier la relation d-h par la sélection et les croisements. Les corrélations génétiques additives entre la relation d-h et la hauteur étaient négatives, avec une moyenne de -0,62. La sélection pour la hauteur produirait donc des tiges plus effilées que la moyenne, ce qui porte à croire que les grands arbres allouent relativement plus de ressources à la croissance en hauteur qu'à la croissance en diamètre. La sélection pour la hauteur uniquement aura un effet négatif sur le gain en volume.[Traduit par la Rédaction]

Effects of phenotypic selection on height-diameter ratio of Norway spruce and Scots pine in Sweden

“…Thus, large trees seems to allocate relatively more resources on diameter growth compared to smaller trees which leads a lower height diameter ratio. However, our findings do not correspond well to the study by Kroon et al (2008), where the genetic correlation between diameter-height ratio and height was estimated to -0.62 for Scots pine. In the study by Kroon et al (2008) the mean height of competitors, environmental inter tree competition index and genetic inter tree competition index were used which could have over compensated for competitive effects.…”

“…In addition, the low to moderate heritability indicates that height-diameter ratios could be modified by selection and breeding, given that the variation is large enough. In this study, the estimated heritabilities for height-diameter ratio were 0.11 for Scots pine and 0.19 for Norway spruce, which corresponds fairly well to the estimated heritability of 0.22 reported by Kroon et al (2008) for Scots pine in northern Sweden. Our findings in this study suggest that selecting for height or diameter will both results in less slender Scots pine and Norway spruce trees.…”

“…The material in the trials was analyzed at the age of 15-22 years when the mean height was 3.2-8.3 m and mean dbh was 3.0-11.9 cm. In order to reduce confounding effects of competition in the analysis, inter-tree competition was calculated in line with the study by Kroon et al (2008):…”

“…Environmental factors and silvicultural treatments largely determine stem slenderness (Kroon et al 2008), although genetic factors may also play an important role (Harrington and De Bell 1996). In a study of Scots pine, Andersson et al (2007) found that plus-tree progenies were more slender than progenies of unimproved trees.…”

Lignification Markers of the Tracheid Walls of Scots Pine (Pinus sylvestris (L.)) in Various Forms of Dead Bark

“…The tree structure, structure of its particular elements (root, trunk, and crown), and the structure and properties of the tree tissue must be responsible for the functional premise of both the conduction system and the biomechanical system. That is why there are numerous connections and dependences between the different characteristics of a tree or wood (Wąsik 2010), particularly between the biometric characteristics determining the size and shape of the crown or of the trunk, which has an influence on the stability of a tree (Kroon et al 2008;Jelonek et al 2012;Cantiani and Chiavetta 2015;Tomczak et al 2015;Motallebi and Kangur 2016). Previous literature on the subject devotes a lot of space to experiments that aim to determine the relation between the growth conditions and the quality of the raw wood (Jelonek et al 2009a).…”