Current issue: 55(1)
Under compilation: 55(2)
The article is a review on the costs of raw materials in the Finnish sawmill industry in 1920s based on statistics collected from the members of the Central Association of the Finnish Woodworking Industries (now Finnish Forest Industries). The article includes statistics about the average size of if the saw timber bought in standing sales from private forests and harvested from the industry’s own forests, stumpage price of the timber, and labour costs of the harvesting of the wood. The average size of the logs was greater in the northern part of Finland, where the sawmills could limit the purchases of smaller timber. In the southern part of the country, the size of the timber decreased in 1922‒1926 due to growing demand of the timber. The long transport distances in the north influenced the costs. The number of logs per tree increased during the period. The level of stumpage price varied considerably in different parts of the country, falling from the south-west to the east and north. Competition of raw material increased the stumpage prices in 1922a and 1926‒27. The international economic downturn influenced the industry in 1929‒1931.
The PDF includes a summary in German.
A theoretical nomogram was made for estimating the costs of fully mechanized thinning and the driving speed of the machine. Based on this nomogram and the previous studies three harvesting methods were compared; systematic fully mechanized harvesting, selective fully mechanized harvesting, and manual felling combined with whole-tree chipping.
The third method was cheaper than the fully mechanized methods in a pole-stage stand. The choice of the most advantageous chipping station depended on conditions, but the smaller tree size and possibly the reduced damage on the remaining stand favour chipping on the strip road rather than chipping on the intermediate landing or at the mill.
Mechanized systematic thinning was the cheapest method for harvesting in the sapling stand. The required driving speed were so low that ergonomic factors should not hinder its use. Factors related to the future production of the stand do, however, limit its use. Mechanized selective thinning does not seem to be an economic method for harvesting in a sapling or pole-stage stand.
The PDF includes a summary in English.
The goal of this study was to develop a mathematical model for determination of the optimal winching distance in different conditions as based on harvesting costs. In the thinned forest the strip roads are parallel and the winching routes perpendicularly to them. A directed felling of trees is used so that it is easy to make loads to be winched. The stems can also be prepared to timber assortments on the stump area and gathered to loads for skidding alongside the winching routes.
After winching the timber is transported using a forwarder mowing on the strip roads. If the stems have not been bucked in the forests, they are to be prepared to timber assortments before the following transportation, because the problem of turning whole stems in a thinned forest has not yet been solved.
In the mathematical model the formation of the costs was described using 18 variables of which 15 had an effect on the optimum winching distance. Some empirical values were estimated concerning these variables, and the corresponding optimum winching distance were computed. The optimum was mainly determined by the quantity of timber harvested per unit area, the size of the winching load, the regression coefficient of the times which were depended on the winching distance.
According to the model, the deviation from optimum winching distance does not cause a very great change in the analysed total costs. When the winching distance is longer, the increase of the costs is smaller than if it is shorter than optimum. In general, the increase of the costs was so small that in practice one obviously can be satisfied with rather approximate methods in determining the suitable winching distance.
The PDF includes a summary in English.