The ratio of heartwood and sapwood influences the mass of the tree trunk and logs, since sapwood moisture content and density in the freshly felled timber differ considerably from that of heartwood (in pine) and colourless heartwood (in spruce) moisture content and density, i.e., sapwood is 3 to 4 times more moist and 1.6 to 1.8 times denser than heartwood.
To determine the proportion of heartwood in pine and spruce and its influence on wood moisture and density in a freshly felled condition depending on the place in the trunk and the sample disc diameter, 989 pine and 676 spruce sample discs were prepared and treated. The sample plots, from which the sample discs were obtained, are scattered all over Latvia’s territory in the most widely represented pine and spruce forest types where the age of the trees ranged from 61 to 143 years old.
Usually greater attention is paid to the log diameter, so that the heartwood proportion could be forecasted. As a tree gets older, the proportion of heartwood increases and with the increase in age the dimensions of the tree trunk also increase, therefore the diameter correlates with the proportion of heartwood. The trunk diameter, similarly as it is in the case of heartwood proportion, decreases towards the top of the trunk, but the moisture content and density of wood increase towards the top of the trunk. The values of the coefficient of determination (R2) are within the range of 0.634 to 0.788, which shows that in 63-79% of the cases the changes in wood moisture and density can be explained by the proportion of heartwood, however it is difficult to automatically determine the proportion of heartwood, especially that of the colourless spruce heartwood.
Keywords: pine, spruce, moisture, density, heartwood
Authors
Millers M.
Forest Faculty, Latvia University of Agriculture
Līpiņš L.
Forest Faculty, Latvia University of Agriculture
Priedkalns G.
Forest Faculty, Latvia University of Agriculture
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