Articles by I. Lassila

Majority of the timber floated in Finland has been floated loose. Repair of the floating channels in the end of 1800s decreased the amount of sunken logs and loss of timber during the transportation. The increase of floating of pulpwood and other small timber has later increased the number of sunken logs. More information is needed on the amount and quality of floated timber, also the floating channels should be classified. A detailed study plan to investigate how big proportion of the timber is lost during floating, which factors influence the sinking of timber, and how the timber dries in the forest depots is presented. A classification of timber by its floatability is presented.

The PDF includes a summary in German.

• Lassila, E-mail: il@mm.unknown

The article reviews the change in how the most sufficient wood material was chosen for different uses. The craftsmen used different characteristics to determine the quality of wood, for instance, tree species, location in the stem, whether it was sapwood or heartwood etc. Scientifically, the quality of the wood has been described by, for instance, specific gravity, bending strength and compressive strength. Durability would, however, be better attribute than strength to describe the quality of wood, because circumstances, like humidity and temperature can change where the wood is used. The article discusses further the development of durability indexes.

The PDF includes a summary in German.

• Lassila, E-mail: il@mm.unknown

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. 

• Lassila, E-mail: il@mm.unknown

The article analyses the efficiency of forest work, and the use of time and motion study methods in forest work. Forest work can be characterized by little use of machinery. It cannot be repeated as orderly as industrial work. This affects also how the efficiency of the work can be measured. Only parts of the work can be timed. The study takes making of piled wood as an example. First are determined the standard times for the work moments. They include the time used to prepare the piled wood, and the waste time. It is concluded that forest work can be standardized with the methods of work analysis.

The PDF includes a summary in English.

• Lassila, E-mail: il@mm.unknown

Earlier research has presented contradictory results of the influence of forest site type on the weight of wood. In this study, dominant trees of Scots pine (Pinus sylvestris L.) was chosen as sample trees on four forest site types: Calluna, Vaccinium, Myrtillus and Oxalis site types. The trees were felled in autumn, when the water content of the wood is low. Weight of the test samples was measured weigh before and after drying. Undried wood, both sapwood and heartwood, is heavier in Myrtillus type than in Vaccinium type. The weight of the air-dried heartwood did not differ between the two forest site types. Air-dried- sapwood was heaviest in Myrtillus site type. Air-dried heartwood was heaviest in Vaccinium site type, and lightest in Oxalis type. Owen-dried sapwood was heaviest in Calluna site type, where the tree growth is slow, but weight differences were small in owen-dried heartwood. It can be claimed that forest type affects wood quality.

The PDF includes a summary in English.

• Lassila, E-mail: il@mm.unknown

The article gives a summary of the range of the wood-technological research, and suggests that the research in the subject in Finland should be divided in two parts: research on problems of wood-technology in the strict sense of the word, and those concerning wood refinement and the problems of wood technology, related to the latter. The wood-technology research would be addressed to the Forest Research Institute, and the research on wood refinement to the organization to be founded by the wood manufacturing industry. Finally, main subjects to be studied are listed.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander. The PDF includes a summary in English.

• Lassila, E-mail: il@mm.unknown

The article includes a detailed review on the technical properties of wood. The weight, water content, strength and conductivity of the wood, and the factors affecting them are discussed. The mechanical and technical properties of wood are influenced, for instance, by tree species, age and part of the tree, geographical situation, site and growth conditions of the stand, anatomical structure of the wood, and temperature. The author summarizes the topics where further research should be addressed. For instance, the forest site types developed in Finland could be utilized in studies of the mechanic technical properties of wood.

The PDF includes a summary in English.

• Lassila, E-mail: il@mm.unknown

The article describes the evolution of sawmills, focusing on four parts: the frame and sliding devices, the fastening of the blade into the frame, appliances for fastening the timber, and feeding devices. The earlier equipment had adaptability that has been lost in the more developed equipment, because the raw materials have been too expensive and hard to acquire, among other things. It is remarked that many inventions of the sawmills have not been adopted in the actual equipment.

The PDF includes a summary in English.

• Lassila, E-mail: il@mm.unknown

The frequency of years when Scots pine (Pinus sylvestris L.) produces cones and seeds affects its reproduction in the north. The study area covered most of the pine lands in Northern Finland. Scots pine seems to be able to produce cones relatively often in the north. The amount of seeds produced in one year was, however, not sufficient to produce a dense seedling stand. Thus, the natural pine stands contain usually trees in different ages-classes, which have germinated in different years. The cone production is highest in 150-170 years old trees. Pine also needs warm summers to produce viable seeds. Brush fires avail the growth of seedlings, because they clear of ground vegetation that hinders germination of seeds. The seedlings need also moisture to survive; good regeneration years have often had rainy summers.

The PDF includes a summary in German.

• Lassila, E-mail: il@mm.unknown