1. Genetic control of Eucalyptus globulus harvest traits
- Author
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Hamilton, Matthew G., Acuna, Mauricio, Wiedemann, John C., Mitchell, Rick, Pilbeam, David J., Brown, Mark W., and Potts, Brad M.
- Subjects
Tree farms -- Research ,Harvesting -- Research ,Forest productivity -- Genetic aspects ,Eucalyptus -- Genetic aspects ,Tree breeding -- Research ,Earth sciences - Abstract
The cost of harvesting short-rotation plantation eucalypts can be in excess of AU$2500 x [ha.sup.-1]. Despite this high cost, the extent to which harvesting productivity is affected by tree genetics is not well understood. We address this issue in a study of two 10-year-old genetic field trials of Eucalyptus globulus Labill. in Australia. Standing-tree traits analysed were survival, diameter at breast height, basal area, and stem straightness and forking. Harvest traits analysed were volume, time, and productivity. Genetic group and within-group genetic variation (additive and dominance), stand-level family variation, phenotypic and genetic correlations, and the effects of inbreeding were estimated for these traits. The different scenarios studied showed that plantation harvest productivity was affected by tree genetics to some degree but was mainly affected through positive covariation with stem diameter. Harvest productivity is thus unlikely to have been adversely affected by past selection. Although no significant additive or dominance genetic variation in stem forking or straightness was detected, weak phenotypic correlations were consistent with harvest productivity being higher in straighter trees with no forking. High inbreeding depression was evident for growth and survival; however, in open-pollinated progeny, this resulted in only a slight reduction in harvest productivity (5.5%) compared with out-crossed progeny. Key words: harvest productivity, additive genetic variation, dominance genetic variation, inbreeding depression, standing-tree traits. Le cout de la recolte de bois d'Eucalyptus en plantations a courte revolution peut atteindre plus de 2500 $A x [ha.sup.-1]. En depit de ce cout eleve, l'influence de la genetique de l'arbre sur la productivite de la recolte est peu comprise. Les auteurs ont aborde cette problematique en etudiant deux tests genetiques d'Eucalyptus globulus Labill. etablis au champ depuis 10 ans en Australie. Les caracteristiques a l'etude des arbres sur pied etaient la survie, le diametre a hauteur de poitrine, la surface terriere, la rectitude de la tige et la presence de fourches. Les caracteres relies a la recolte des arbres etaient le volume, la duree de la recolte et la productivite de cette derniere. Pour ces caracteres, la variation genetique additive et de dominance au sein des groupements genetiques et entre ces derniers, la variation familiale a l'echelle du peuplement, les correlations phenotypiques et genetiques ainsi que les effets decoulant de la consanguinite ont ete estimes. Les differents scenarios etudies ont indique que la genetique avait, jusqu'a un certain point, un impact sur la productivite de la recolte des plantations et cela principalement par le biais d'une covariation positive avec le diametre de la tige. Il est donc peu probable que la productivite de la recolte ait pu etre affectee negativement par la selection passee. Alors qu'aucune variation genetique significative de nature additive ou de dominance n'a ete observee pour la presence de fourches ou la rectitude de la tige, de faibles correlations phenotypiques etaient coherentes avec la productivite de la recolte qui etait plus elevee lorsque les arbres etaient plus droits et exempts de fourches. Une depression consanguine elevee a ete observee dans le cas de la croissance et de la survie. Cependant, cela n'a entraine qu'une faible reduction de la productivite de la recolte (5,5 %) chez les descendants issus de pollinisation libre comparativement aux descendants issus de fecondation croisee. [Traduit par la Redaction] Mots-cles : productivite de la recolte, variation genetique additive, variation genetique de dominance, depression consanguine, caracteristiques des arbres sur pied., Introduction In recent decades, mechanised forest harvesting systems have been widely adopted, primarily to reduce harvest costs and improve worker safety. Time and motion studies of mechanical harvesting operations have [...]
- Published
- 2015
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