Irbe, I., Sable, I., Treimanis, A. and Jansons, A. 2013. Variation in the Tracheid Dimensions of Scots Pine (Pinus sylvestris L.) and Lodgepole Pine (Pinus contorta Dougl. var. latifolia Engelm) Trees Grown in Latvia. Baltic Forestry 19(1): 120 - 127

Wood anatomical properties of 27-year-old Scots pine (Pinus sylvestris L.) (n = 32) and lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm) (n = 19) sample trees grown in Latvia were investigated. Stem diameters, growth rings, and dimensions of 150 earlywood (EW) and 150 latewood (LW) tracheids per sample tree were measured. Lodgepole pine demonstrated significantly (p < 0.05) larger stem diameters (21%), wider growth rings (8%), and higher LW content (15%) than Scots pine. Tracheid dimensions such as lumen area and diameter, and mean tracheid diameter of EW were significantly higher in Scots pine, while tracheid wall thickness was higher in lodgepole pine. Lumen area and diameter of LW were significantly higher in lodgepole pine. Scots pine had tracheids with larger average lumen area (10%) and diameter (5%), radial diameter (8%) and tracheid diameter (3%), while lodgepole pine had thicker tracheid walls (6%) and longer fibres (10%). Tracheid wall thickness and average diameter of EW and LW cells increased from pith to cambium in both pine species. The number of tracheids was assumed to play more important role than tracheid size in the increment of the stems and growth rings of lodgepole pine.

Key words: Wood anatomy; Tracheid dimensions; Earlywood (EW); Latewood (LW); Lodgepole pine; Scots pine