Wood Density, Annual Ring Width and Latewood Content in Larch and Scots Pine

The wood density, annual ring width and latewood content in five different species oflarch (Larix Mill.) and in Scots pine (Pinus sylvestris L.) were investigated using direct scanning X-ray densitometry. In total 106 trees were investigated. Old, 120-150 year, Siberian larch (Larix sibirica Ledeb. and Larix sukaczewii Dyl.) grown in Krasnoyarsk and Archangelsk and 105 year-old European larch (Larix decidua Mill.) grown in Sweden had on an average 20-25 % higher wood density than Swedish Scots pine. The variation in density between different trees of the same species was big. Average wood density of larch trees was 618 (535-670) kg/m3 in old Siberian larch and 621 (550-665) kg/m3 in mature European larch timber grown in Sweden. Average wood density for the young, 30-35 years-old, larch trees was 536 (515-560) kg/m3 for European larch, 451(410-490) kg/m3 for hybrid larch (L. x eurolepis Henry) and 452 (420-490) kg/m3 for Japanese larch (L. kaempferi Lamb.). Corresponding figures for mature Scots pine was 504 (475-555) kg/m3. The density within the mature zone of the heartwood was 20-40 % higher than in the juvenile wood zone. The density in mature European and Siberian larch heartwood, usually reached 650 kg/m3 after 25-30 annual rings from the pith. The density of larch heartwood increased with annual ring width up to 2.5 mm and decreased with