Current issue: 58(5)
Silva Fennica vol. 17 no. 2 | 1983
Category : Article
The aim of this concise interview survey was to collect information about the servicing properties of forest tractors. Ten interviewees gave grades (in a scale from 4 to 10) concerning two servicing properties of various types of forest tractor. The rating covered the general safety during servicing (structural serviceability) and work postures during the work. Four types of forest tractor widely-used in Finland were chosen. The forwarders were of different size and structure.
According to the rating, the lightest forwarder was clearly superior to the other types. This machine was also the smallest in size and the most modern. Differences between the other three forwarders were not quite so clear. The variation between the machines as regards both so-called easy and troublesome tasks was considerable. Lubrication of the articulated shafts and supporting bearings was, however, very troublesome regardless the machine type. The heaviest tractor was considered the most difficult to service.
The PDF includes a summary in English.
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Rieppo,
E-mail:
kr@mm.unknown
- Väyrynen, E-mail: sv@mm.unknown
Empirical measurements showed that the strength of a dead branch of Scots pine (Pinus sylvestris L.) was related to the second power of the branch diameter and the third power of the basic density of branch wood. The same factors affected also the strength of living branches. Especially, the contribution of wood density was important. The significance of the results is discussed considering the natural process of self-pruning and its effect on the branchiness of the stem.
The PDF includes a summary in English.
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Kellomäki,
E-mail:
sk@mm.unknown
The usefulness of some international bibliographic databases for Finnish forest researchers was studied. In this study, 26 gratis online searches from one or more databases was made. The searches were carried out using mainly AGRICOLA, BIOSIS and CAB databases. The most used database was CAB, which includes Forestry Abstracts. The relevance of the references retrieved was evaluated by the users. Recall, precision, novelty and overlap of the references were measured. The users evaluated the results and costs of their search. Some previous comparable studies are reviewed.
The PDF includes a summary in English.
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Karjalainen,
E-mail:
ak@mm.unknown
- Hyväkkä, E-mail: lh@mm.unknown
- Kärki-Folkersma, E-mail: sk@mm.unknown
Methods involving the use of moving averages, trend surfaces and their combination are compared in deriving local values of monthly mean temperatures and precipitation sums from the observations made by the Finnish Meteorological Office. Correlation between meteorological variables and sea index, lake index and height above sea level were used in the trend surface method and in the combined method. Combined method, with a trend surface calculated from means of a long time period, was the most reliable method to estimate long local time series.
A method to calculate unbiased estimates of effective temperature sums from monthly mean temperatures is presented.
The PDF includes a summary in English.
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Ojansuu,
E-mail:
ro@mm.unknown
- Henttonen, E-mail: hh@mm.unknown
In order to evaluate the strength properties of boards made from small and large Norway spruce (Picea abies) butt logs, 15 small (top end diameter 13 cm) and 15 large (top end diameter 25 cm) logs were sampled from a sawmill in Finland. From each log two test pieces were made in order to measure the bending and compression strength, dry density and average ring width.
The boards from small logs were stronger and their density higher. When the differences between groups were analysed it was found that the strength was determined by the density and ring width. When the density was kept constant, the increase in ring width had a decreasing effect on the strength properties. Because there was a negative correlation between ring width and density, ring width alone had a great effect on the strength properties.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
- Hakala, E-mail: hh@mm.unknown
A population consisting of 450 Norway spruce (Picea abies (L.) H. Karst.) samples was gathered from northern and southern Finnish wood. The static bending strength was affected greatly by the density of the wood. However, keeping the density constant, the bending strength was higher in northern than in southern Finnish wood. The reason was the effect of the growth ring width.
The basic density was affected by the growth rate. Keeping the growth ring width constant, the basic density was over 5 kg/m3 lower in northern than in southern Finnish wood. This result supports the earlier findings on the effect of latitude.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
- Dumell, E-mail: od@mm.unknown
A study on the bilberry (Vaccinium myrtillus L.) was made in the municipality of Pihtipudas (about 63° 30’ N, 23° 30’ W) in 1977. Berry yield was surveyed by picking along 17 lines, each 1,000 m long. The lines were chosen randomly and were situated on different vegetation types throughout the municipality. The picking and use of bilberries were studied by an inquiry addressed to a random sample of families living in the area. Marketing of bilberry was investigated by means of report based on purchasing certificates.
The total yield of bilberry in Pihtipudas was 2.4 million kg (21.9 kg/ha). The yield per hectare were best on Vaccinium and Myrtillus type sites, and on swampy heath sites, where the yield was about 27–65 kg/ha, 50% of the yield on the Vaccinium type and 25% of that of Myrtillus type. Only 1.8% of the total bilberry yield was picked from old forests. Women contributed 54, men 34 and children 12% of the volume.
72% of the berries were used for home consumption by the families, 24% were sold and 4% were used for other purposes. The earnings from bilberries for the families that sold berries was in average FIM 178.
The PDF includes a summary in English.
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Raatikainen,
E-mail:
mr@mm.unknown
- Raatikainen, E-mail: tr@mm.unknown
Using literature and a simulator experiment, an ordinary processor and a grapple loader processor were compared in conditions corresponding to thinning later than the first commercial thinning. Visual bucking only was employed in the simulator experiment. The strip road spacing was 30 m and there was no preliminary skidding of the trees. The simulator experiment confirmed the view reached in the literature that work productivity of the grappler loader processor is 20–40 % greater than that of an ordinary processor provided that the stem size is under 0.2–0.4 m3.
The PDF includes a summary in English.
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Harstela,
E-mail:
ph@mm.unknown
- Maukkonen, E-mail: am@mm.unknown
