Genetic Variation Amongst and Within The Native Provenances of Pinus radiata D. Don in South-eastern Australia. 2.Wood Density and Stiffness to Age 26 Years

Abstract

Two progeny trials of native provenances of Pinus radiata, representing the 1978 seed collection, were assessed for wood density and standing tree acoustic velocity. One trial, planted in 1980 in southern New South Wales, Australia contains all five provenances. The second trial, planted in the same region in 1982 contains only the island provenances. Results for extracted wood density, assessed from pith to bark in 5 ring segments, and standing tree acoustic velocity, measured at age 24 or 26 years, are reported.Large differences between the mainland and island provenance were apparent for wood density and stiffness. The mainland provenances were very similar for density and followed the "normal" pattern of change with a gradual increase from the pith, followed by a plateauing around age 20. Neither of the island provenances followed this pattern of change in density: Cedros had stable density across the 4 inner most segments and Guadalupe had stable density for the inner two segments followed by a linear increase. Juvenile density was higher in both the island provenances than the mainland provenances. The island provenances differed from each other for standing tree acoustic velocity, with velocity being higher in Guadalupe provenance.Heritabilities for wood density and acoustic velocity (average 0.37) were higher than those for tree growth and form. Across the stem radius, heritability of density was variable with some segments having zero heritabilities in some provenances, particularly Cambria, Cedros and Guadalupe. Heritability for acoustic velocity was highest for Cambria and the island provenances. Within the mainland provenances, little difference was found between populations for either wood density or acoustic velocity. Density and standing tree acoustic velocity were negatively genetically correlated with tree diameter.Differences in provenance means were greater for acoustic velocity than for density in the outermost segment. Provenance rankings also differed, with the rankings for acoustic velocity being similar to those for density in the 2 nd segment from the bark. The genetic correlations between density and velocity reached a maximum for 3 rd segment. These results indicate that outerwood density is not the sole driver of acoustic velocity, and that the sound wave is perhaps not travelling through the outer most wood, but is penetrating some distance into the tree.

Basic density, diameter and radial variation of Vanuatu Whitewood (Endospermum medullosum): potential for breeding in a low density, tropical hardwood

“…The apparent absence of either phenotypic or genotypic correlations between DBH and DEN, is encouraging and suggests that improvement of these traits might proceed in tandem without adverse effect, though again, this finding should be checked by more precisely determining genetic correlations in future. Adverse genetic correlations between growth and wood property traits in some Pinus spp., particularly P. radiata, (Wu et al 2008, Kumar et al 2008, Raymond and Henson 2010, Gapare et al 2011 have been a serious impediment to progress, particularly as the adverse correlation (i.e., high growth correlated to high proportions of juvenile wood with low density and strength) was not identified until well after selection for growth had taken place, necessitating expensive and time-consuming remedial restructuring of breeding populations. environmental variation undoubtedly exists across Vanuatu's numerous islands, Genotype by Environment (GxE) experiments, established across varying climatic and edaphic conditions (White et al 2007) will be necessary to test the assumption of superiority of Santo provenances and identify whether or not other locally specialised provenances exist (Doran et al 2012).…”

“…Greater variation in density was found within trees (radially at breast height) than between trees, families or provenances. This large pithto-bark increase in density is characteristic of tropical pioneer angiosperm species (Wiemann and Williamson 1988, Butterfield et al 1993, Raymond and Henson 2010, Lachenbruch et al 2011. Juvenile trees, such as those sampled in this experiment, are adapting to changing hydraulic and mechanical demands placed upon wood due to growth.…”

“…Narrow-sense heritability is generally low for growth traits (e.g., DBH) and moderate to high for wood property traits (e.g., DEN) (Falconer andMackay 1981, White et al 2007) in both softwood and hardwood species. Both DEN and heritability generally increase with radial distance from the pith for both softwoods (Wu et al 2008, Gapare et al 2009, Raymond and Henson 2010 and hardwoods (Butterfield et al 1993, Hein et al 2012. However the opposite can be true for some species (Bush et al 2011).…”

“…However the opposite can be true for some species (Bush et al 2011). Genetic correlations between DBH and DEN are often strongl y negative for coniferous species (Wu et al 2008, Raymond and Henson 2010, Gapare et al 2012.…”