Silva Fennica vol. 9 no. 3 | 1975

The ash content has been found to correlate with the fertility of peatlands. Relationship between height of 80-year-old stands and ash content of peat in topmost 30 cm layer was examined in Lithuanian conditions. On drained peatlands with ash content of peat from 3% to 8% pine stands increase in height. Ash content of peat being about 7% Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on drained sites are found to be of equal height. Ash content of peat more than 8–9% has no significant effect on growth of pine or spruce stands. Birch (Betula verrucosa (B. Pendula Roth.) and Betula pubescens Erhrh.), stands are less sensitive to ash content of peat compared with other species. Black alder (Alnus glutinosa L. Gaertn.) stands occurred in sites with ash content of peat more than 8–10%. The height of the stands become equal both in drained and undrained sites in the cases where ash content of peat is about 16–18%. Ash (Fraxinus exelsior L.) stands attain high productivity on drained sites with ash content of peat about 20%.

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• Kapustinskaité, E-mail: tk@mm.unknown

In the first place the term short-rotation forestry is being used in the sense of intensive tree growing during a short rotation time using reproduction by coppice shoots from broad-leaved tree material which has been specially bred for this purpose, or of producing fast-growing varieties from planted stock during the course of somewhat longer rotation time (maximum 20 years). However, short-rotation forestry as such has already a long history.

In the Fertile Crescent in ancient Egypt grew no tree species suitable for short-rotation production, but reeds and bulrushes were used for the same purpose as willow-twigs, e.g. wickerwork or binding. At least in the Fertile Crescent reed harvesting using a rotation of one year was practiced already very long ago. The earliest information about coppice-shoot cultivation is found in Greek literature, but it was the Romans who developed short-rotation forestry based on the trees’ capacity of reproducing through coppice shoots into an extensive economic activity. Willows were by far the most important species used. Twigs intended for wickerwork were harvested once a year and thicker material, to be used for support and in basket framework, every fourth year. Chestnut and oak were used for the production of slightly thicker poles employing a longer rotation. Cypress poles were produced from seedlings using a rotation time of 12–13 years. Roman scholars give us plenty of information concerning the tending of plantations in short-rotation forestry.

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• Makkonen, E-mail: om@mm.unknown

The aim of the study was to determine the extent to which the cross section of birch (Betula sp.) and aspen (Populus tremula L.) logs differ from a circle and to test some simple methods for measuring the cross-sectional area which can be used, for instance, for determining the volume of the logs. The material consisted of 420 debarked birch disks and 240 aspen disks which were representative of the logs arriving at two factories.

The convex deficit values for the material were very small, the cross-sectional area error being in general less than 1%. On the other hand, the other parameters deviated from the circular form to quite a large degree. It was also evident that the radii measured from the piths to the surface of the wood varied considerably more in the same disk, as regards length, than the diameters measured in different directions.

It was evident that the shape of the average cross-sectional area was not in general elliptical. It thus appears that any method for measuring the cross-sectional area which is based on elliptical formula is not suitable. The method which gave the best result was that in which the cross-sectional area was taken as the average of the area of the circle calculated from the smallest diameter and that calculated from the diameter passing at right angles to it. This method also appeared to be the best for disks which deviated to quite a large degree from the circular form. The suitability of this method is increased by the fact that the relative error is only slightly dependent on the size of the disk.

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• Kärkkäinen, E-mail: mk@mm.unknown

During the next decade there will be a marked increase in the allowable cut in drained peatlands. At the same time, the mechanization in logging proceeds, and in short-distance haulage the use of forwarders will increase. This study, based on literature and some observations, deals with logging conditions in drained peatlands with special reference to the suitability of heavy logging machines for use in such terrain. In addition, soil frost and the bearing capacity of the frozen peat soil were studied.

Freezing of the soil in a drained peatland area depends prevailingly on the weather conditions during early winter. The factors influencing soil freezing of a drained peatland are completely different from those regulating the freezing of natural peat soils. The frost penetrates in general deeper in the drained than virgin peatland. The topmost peat layer does not, however, freeze uniformly. Generally speaking, the bearing capacity of a drained peat soil is lower than that of undrained peat due to lower water content.

It is concluded that heavy logging machines are probably not fitted for use in drained areas on peatland even if the average soil frost values recorded would suggest it. Moreover, because of their extremely superficial root systems, peatland forests are exposed to damages by heavy machines in thinning operations.

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• Hannelius, E-mail: sh@mm.unknown