Comparisons of some properties on wood quality among clones grafted with the elites of Abies sachalinensis, 1: Using thinned trees in the Hattari and Aichi seed orchards

In order to practice afforestation of good quality trees, many grafted clones of various elite trees, including Abies sachalinensis Mast., have been planted for seed production in seed orchards in Hokkaido. Some properties of wood quality of A. sachalinensis were examined by using the clones thinned in the Hattari and Aichi seed orchards in southern Hokkaido. A. sachalinensis is the forest tree with the most growing stock (about 100 million m3 or 20% of total stock) in natural forests, and one of the most popular planting trees, the wood of which is soft creamy white in color and light in weight, so that its lumber has usually been used for house construction and its waste for pulp in Hokkaido. However, woods with too low density and too wide annual ring width are frequently seen, and they are not suitable for construction timber. Meanwhile, trees with extremely high moisture content in heartwood are also seen, a condition of which causes the stem to crack in winter and the wood to deteriorate (crack, collapse, or strain), when it is dried. From the two seed orchards, we obtained 43 clones totaling 230 individuals, and examined their basic density, mean annual ring width, and moisture content in heartwood with 8-cm thick stem disks, and investigated them statistically. Furthermore, the repeatability, or heritability in a broad sense, of these properties was calculated. The results are as follows: The average basic densities of heartwood were 301kg/m3 and 276 kg/m3 in the clones grafted from both natural and planted elite trees in the Hattari and Aichi seed orchards respectively, while the average basic densities of sapwood were 312 kg/m3 and 281 kg/m3 respectively. The average mean annual ring widths were 5.3mm and 6.5 mm in the clones of the Hattari and Aichi seed orchards respectively. The fact that the clones obtained from the latter have wider annual ring width and lower density means that the latter's conditions, including climate and soil, are better than the former's. Consequently, the growth of the latter's clones is superior to the former's. The average moisture contents in heartwood were 59.8% and 76.6% in the clones of the Hattari and Aichi seed orchards respectively, though the coefficients of variation were large within each clone