Current issue: 54(2)
Under compilation: 54(3)
The quality of timber is very important in trade and dependable on the purpose of the timber. The article describes the influence of the forest type on the mechanic-technical properties of the timber. The studied properties are weight, the mean breadth of the annual growth rings, and the compression strength.
The percentage of the annual growth rings that is formed during the autumn is characteristic for the compression strength, and it varies accordingly on different forest types. The result from the formula of Janka depends on the forest type.
Being able to classify the timber according its quality makes it possible to have better price for it. it is also important when deciding for what purpose the timber can be used.
The PDF contains a summary in Finnish.
The hard climate and other environmental conditions cause irregularities in the growth of trees in Lapland. Those changes weaken the characteristics of the tree for industrial use and hence lowers the timber price. The eccentricity is mainly caused by the strong wind burden.
The data for the article consists of 428 increment core samples from pine trees different ages, sizes and growth rate. There were collected in years 1910-1912 in Finnish Lapland, regions Utsjoki and Inari. The increment cores were collected on the height of 1.3 meters in south-north direction straight crosswise through the whole tree. The difference of length was measured between southern and northern half rays. Earlier studies show that the eccentricity remains the same in different heights of the tree. Hence studying the variations only on the breast height radiuses is possible.
The mean eccentricity is 12.3% and its maximum varies mostly between 20 and 25%. There are no differences in eccentricity between trees of different age classes or diameter.