Silva Fennica vol. 16 no. 4 | 1982

In forestry, a classical method of evaluating the profitability of an outlay is to calculate the internal rate of return. If there are many outlays and returns over a period, analytical determination of the internal rate is difficult and requires simulation methods. However, if there is only one outlay and one return, the computation is easy. In this paper, some formulae were developed for practical purposes. The equations also show how the return changes as the ratio between the return and the outlay changes.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown

Application of nitrogen at levels of 200, 400 and 600 kg ha^-1 resulted in increases of 35, 18 and 12% in the photosynthetic rate in young Scots pine (Pinus sylvestris L.). The number of buds, degree of branching, and needle size were positively related to the amount of nitrogen applied. A 10–40% increase in the average needle area was found. A positive correlation was found between total photosynthesis and stem growth.

The PDF includes a summary in Finnish.

• Kellomäki, E-mail: sk@mm.unknown
• Puttonen, E-mail: pp@mm.unknown
• Tamminen, E-mail: ht@mm.unknown
• Westman, E-mail: cw@mm.unknown

Relationships between densities of pine bark bug, Aradus cinnamomeus Panzer and the height growth of young Scots pine (Pinus sylvestris L.) were studied in several habitats, including a highly infested area in Southern Finland. The slower the growth of the pines was, the greater was the height up to which bugs were found. On the average, maximum bug density was noted at a height corresponding to a fifth of the height of the tree. In stands restocked by natural generation, the greatest bug densities were noted in pines about three metres high and over twenty years old. Bug densities in trees whose height growth had been decelerating for five years were twice those in trees whose growth was accelerating. A significant negative correlation was found between the bug density and the last-year height increment.

The PDF includes a summary in Finnish.

• Heliövaara, E-mail: kh@mm.unknown

The monoterpene composition of the needle oil of Pinus oocarpa Schiede ex Schltdl. and Pinus caribaea Morelet growing in Zambia were studied by means of GC-MS. P. oocarpa needle samples were taken from 29 trees representing different clones in a seed orchard and from 43 trees in a commercial plantation in 1980. The P. caribaea needle samples were collected from 17 clones in a seed orchard.

Nine compounds were positively identified in the monoterpene fraction of P. oocarpa and eight in that of P. caribaea. The amounts of these compounds showed marked tree-to-tree variation and the sample trees were screened into distinct groups on the basis of the variation. The results give a basis for selection in favour of pest resistance and turpentine yield.

The PDF includes a summary in Finnish.

• Löyttyniemi, E-mail: kl@mm.unknown
• Hiltunen, E-mail: rh@mm.unknown
• Löyttyniemi, E-mail: rl@mm.unknown
• Räisänen, E-mail: sr@mm.unknown

A material consisting of 21 common alder (Alnus glutinosa (L.) Gaertn.) trees from 11 stands was collected. From each stem discs were sawn by 2 m interval. Samples were taken of the discs from various distances from pith. They were macerated and the average fibre length was based on 50 observations.

The fibre length increased significantly from the pith to the disc surface. The increase was approximately similar at various heights of the tree. The tree characteristics had only minor effect. However, near the pith the increase in fibre length was higher in trees with wide growth rings than in other trees. Near the disc surface the growth rate had no effect. In typical pulpwood bolts the average length was 800–950 μm which corresponds well to the data given in the literature.

The PDF includes a summary in English.

• Haarlaa, E-mail: rh@mm.unknown
• Kärkkäinen, E-mail: mk@mm.unknown

Certain trends in the sales behaviour of private non-industrial forest owners suggest that the forest industries have to rely on a raw material supply much less than the allowable cut. This paper deals with several factors responsible for the change in sales behaviour during the last 20–25 years. These changes are caused by social change, a multi-face process which is led by industrialization. It is manifested in the increasing division of labour, more pronounced strive for efficiency, change in social values for the benefit of the adoption of innovations and thus of further changes.

It has become more common than previously to borrow money instead of selling timber. An incentive for doing so is provided by the increased progression of income tax scales which makes it more profitable than earlier to substitute a loan for timber sales with a view to reduce the amount of taxes. In 1977, the real value of the farmers’ debts was 1.7 times as large as in 1970. Inflation provides a further incentive to borrow money rather than to sell timber, because it tends to reduce debts, whereas a growing stock keeps increasing without affecting the property taxation, maintaining its real unit value.

Certain forestry policy measures conductive to increasing the forest owner’s willingness to sell timber are suggested. Among the most promising seems to be an adjustment of the present area-based yield taxation so as to take into account the age class distribution of the growing stock.

The PDF includes a summary in Finnish.

• Riihinen, E-mail: pr@mm.unknown