Genetic control of Eucalyptus globulus harvest traits

Abstract

The cost of harvesting short-rotation plantation eucalypts can be in excess of AU$2500·ha−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.

Inbreeding depression and differential maladaptation shape the fitness trajectory of two co-occurring Eucalyptus species

“…The red line represents the overall average for the trial site , the blue line represents the historical climate average prior to the detectable signature of climate change in the southern hemisphere (Abram et al 2016(Abram et al ) (1911(Abram et al -1959, the green line corresponds to the climate average often used to represent the contemporary climate , and the grey line corresponds to the climate average during the growth period at the trial productive site. While harvesting productivity is positively related to tree size (Hamilton et al 2015), the extent and timing of the translation of ID from growth to survival are unlikely to have a significant economic impact on wood production in eucalypt plantations. This is because most small selfs would be expected to be dead by harvest age in the case of even short-rotation pulpwood regimes or to have been artificially thinned prior to harvest in the case of longer-rotation solid wood regimes.…”

Independent lines of evidence of a genetic relationship between acoustic wave velocity and kraft pulp yield in Eucalyptus globulus

“…Two adjoining unthinned and unpruned E. globulus genetic trials, herein referred to as Trial 1 and Trial 2, were studied. These trials were the subject of a previous study of growth and harvesting traits (Hamilton et al 2015a). Data from Trial 1 were used to estimate quantitative genetic parameters, and data from Trial 2 were used for QTL analyses.…”

“…The trial was designed according to a modified rowcolumn design at the plot level, where over-represented families were randomly assigned to plot positions of under-represented families. (see Freeman et al 2013 andHamilton et al 2015a, for more detailed descriptions of pedigrees and trail designs).…”

“…The models included as fixed effects in b the overall mean and replicate. The random effects in u were incomplete block within replicate, genetic group general combining ability (GCA), genetic group specific combining ability (SCA), the additive genetic component within genetic group and full-sib family within genetic group (refer to Hamilton et al 2015a). For each trait, the narrow-sense heritability (h 2 ), coefficient of additive genetic variance (CV a ), dominance variance σ 2 d and dominance ratio (d 2 ) were estimated from univariate analyses as follows:…”

Impacts of Early Thinning of a Eucalyptus globulus Labill. Pulplog Plantation in Western Australia on Economic Profitability and Harvester Productivity

“…Forking was the major stem form defect recorded in the current trial and accounted for 7% of the variation in harvester productivity. The proportion of forking in the current trial was much greater than that reported in recent trials in other Australian Eucalyptus globulus plantations [45,46]. The forking was likely to have mainly resulted from parrot damage recorded at the trial site as forking has been found to be the most common defect resulting from parrot damage [40].…”