Current issue: 58(5)
Silva Fennica vol. 19 no. 4 | 1985
Category : Article
There are great impact forces in mechanized harvesting and wood yard in the mills which can cause breaks in timber. The impact strength of timber in green condition was tested in temperatures of +18°C and -18°C using sawn pieces (20 x 20 x 300 mm) of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), birch (Betula pendula Roth and B. pubescens Ehrh.), grey alder (Alnus incana L.) and aspen (Populus tremula L.). In addition, unbarked naturally round sticks (length 300 mm, diameter 15 and 35 mm) of the same species were tested.
The impact strength of round sticks was 1.5–4.4 times as great as that of sawn pieces. The reasons are possibly the avoidance of cell breaks at the surface as well as growth stresses. The frozen samples were clearly weaker than the unfrozen ones. As a rule, the impact bending strength increased with increased density of the species. However, the correlation varied greatly between species. If density was kept constant, an increase in the growth ring width decreased the impact strength. The reason may lie in the fracture mechanism.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
- Pietilä, E-mail: jp@mm.unknown
- Vihola, E-mail: rv@mm.unknown
In a greenhouse experiment that lasted for two years, nitrogenase activity, height growth and biomass production was compared in six clones of alder of which four were clones of Alnus incana and two A. incana x A. glutinos hybrids. In addition, the effect of a fertilizer nitrogen gradient was tested on one of the clones.
Clonal differences in height growth and nitrogenase activity were recorded at the end of the first growing season. The growth rhythm of some of the clones changed markedly during the second growing season but differences in nitrogenase activity between clones levelled out. Nitrogen fertilization suppressed nodulation during the first growing season, and also the following year the nitrogenase activity was significantly higher in alders grown without nitrogen supplement. Height growth and total biomass production was also depressed at rather low nitrogen levels.
The PDF includes a summary in Finnish.
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Palmgren,
E-mail:
kp@mm.unknown
- Saarsalmi, E-mail: as@mm.unknown
- Weber, E-mail: aw@mm.unknown
A method for calculation of the effect of practical fertilization for economic evaluation is presented and discussed. 55 Norway spruce (Picea abies (L.) H. Karst.) dominated stands on Oxalis-Myrtillus type sites were surveyed five to eight years after fertilization with nitrogen (90-170 kg/ha). The relationships between the fertilization effect and various stand characteristics were discussed. Fertilization increased the growth of the stands on an average by 2.2 m3/ha/year. In total the increase of tree growth during the research period was 17.5 m3/ha. This corresponds to a yield of 525–659 FIM/ha.
The PDF includes a summary in English.
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Westman,
E-mail:
cw@mm.unknown
- Leikola, E-mail: ml@mm.unknown
- Nummi, E-mail: tn@mm.unknown
The size, nutrient contents and terpene composition of needles of Scots pine (Pinus sylvestris L.) saplings untouched and repeatedly browsed by the moose (Alces alces L.) were compared. Material was collected from a 14-years old and 2.5 m high pine stand in Bromarv, Southern Finland. The average length and fresh and dry weight of the needles were measured, and nutrient content (N, P, K, Ca, Mg, B, Cu) was determined.
The needles of repeatedly browsed pines became long and robust. There was, however, no difference between the dry matter percentage between the needles. The average nitrogen content was higher in the rebrowsed trees. Nitrogen content is, however, not directly correlated with the palatability of pine needles. Even phosphorus and boron content were higher in the damaged trees. No difference was found in Ca, K, Mg and Cu contents of the browsed and control pine saplings.
The PDF includes a summary in Finnish.
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Löyttyniemi,
E-mail:
kl@mm.unknown
Totally 653 battens and planks sawn from butt logsof Scots pine (Pinus sylvestris L.) were chosen from 3 saw mills. The sawn goods were sorted according to normal sorting principles. In order to determine growth rate in the youth, the mean value of the average ring width was measured at the butt end at various distances from the pith.
The average ring width increased as the quality of the sawn goods decreased. The difference between the quality classes in ring width was measured between 2 and 4 cm from the pith. As the size of sawn goods, and, simultaneously, the log size increased, the average ring width increased in a given quality class. Research reinforced previous results, in which slow diameter growth of young Scots pines has been shown to reflect the good quality of sawn goods.
The PDF includes a summary in English.
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Halinen,
E-mail:
mh@mm.unknown
A methodology to evaluate forestry programs aimed at increasing timber supply from nonindustrial private forests is presented that aggregates the marginal social cost and marginal social benefit of a sample program participants and compares them in a benefit-cost efficiency ratio. The paper exposes a methodology followed to evaluate several forestry programs in Massachusetts, USA, and discusses its advantages and inconveniences compared to the other methodologies that have been used for the same purpose. The marginal analysis is based on detailed property and landowner behaviour surveys which are costly but represent a good standard to compare the performance of other approaches.
The PDF includes a summary in Finnish.
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Harou,
E-mail:
ph@mm.unknown
Early growth of four different tree species (Pinus sylvestris L., Picea abies (L.) H. Karst., Larix sibirica Ledeb and Betula pendula Roth) 16–23 years after planting were compared in a field experiment of 16 square plots established on a stony, grove-like upland (Oxalis-Myrtillus forest type) in Southern Finland. This study gives additional results to the publication Folia Forestalia 386/1979.
At this early stage, the growth of the spruce stand was clearly slower than that of the other species for all parameters to be measured (height, diameter, and volume growth). Height growth was most rapid in the silver birch stand and diameter growth in the larch stand. No clear differences were found in the mean volume of the 100 thickest trees in the stand between the larch and silver birch.
The PDF includes a summary in English.
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Parviainen,
E-mail:
jp@mm.unknown
The area of world forests is gradually declining because of various human activities, such as shifting cultivation, uncontrolled logging and industrial pollution. Continuation of the trends would have detrimental ecological, economic and social effects on global scale. The diversity of the problem is wide. The situation in the tropical developing countries differs from that in the industrialized world. With the present rates of population growth and unchanged forest policies, the fuelwood shortage in developing countries is rapidly aggravating. The need for more agricultural land tends to prejudice conscious efforts to increase wood production.
The industrialized countries are experiencing problems in introducing forest policy means to maintain sufficient timber supply. Rapidly increasing pollution problem cause a serious hazard to the existence of the whole forest ecosystem. Forestry has primarily been a national issue of relatively low priority in political decision-making, which has resulted in insufficient action to remedy the situation at national and international level.
The renewability of forest resources represents a strategic asset, the importance of which is bound to increase in the long-run potential for badly needed economic and social change in the world’s poor rural areas will be lost.
The PDF includes a summary in Finnish.
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Simula,
E-mail:
ms@mm.unknown
