Current issue: 53(1)

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Silva Fennica 1926-1997
Acta Forestalia Fennica

Silva Fennica 1926-1997 vol. 21 no. 2 | 1987

Category: Article

article id 5315, category Article
Seppo Kellomäki, Matti Seppälä. (1987). Ekosysteemimalliin perustuvia laskelmia puun korjuun ja metsänkäsittelyn vaikutuksesta männikön ravinnekiertoon ja tuottavuuteen. Silva Fennica vol. 21 no. 2 article id 5315.
English title: Simulations on the effects of timber harvesting and forest management on the nutrient cycle and productivity of Scots pine stands.

Effects of varying rotation, thinning, fertilization and harvest intensity on the productivity and nitrogen cycle of Scots pine (Pinus sylvestris L.) stand were studied on the basis of computer simulation. The increasing intensity of management increased the loss of nitrogen in the cycle. Short rotation, associated with early thinning by means of the whole tree harvest, proved to be especially detrimental regarding the productivity of the forest ecosystem. Fertilization associated with thinnings is of great importance in maintaining the productivity of a forest ecosystem during an intensive timber harvest.

The PDF includes an abstract in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 5314, category Article
M. Saarilahti, E. Bakena, G. Mboya, T. Minja, T. Ngerageze, J. Ntahompagaze. (1987). Tutkimuksia metsätyöstä Tansaniassa. Silva Fennica vol. 21 no. 2 article id 5314.
English title: Studies on Tanzanian forest work.

Four teams of two workers were time-studied in clearcutting of a cypress plantation and three teams in sulky skidding. The heart rate was recorded every 30 s. The average heartrate in timber cutting was 117.5 ± 13.4 P/min, and it was mainly dependent on worker’s working capacity. Average work load index was 41 ± 3% when working at 97% performance. The production rate was then 2.5 m3/h (crew). In sulky skidding the heart rate was lower, 106 ± 1.1 P/min, as well as the work load (WLI 30 ± 1%) and performance rating (87%). The low production rate (1.1 m3/h) (crew)) over 45 m distance is mainly due to under-dimensioned load size. The energy expenditure in timber cutting was 21.4 kJ/min and in sulky skidding 16.3 kJ/min. Daily energy expenditure was 15.0 MJ/d, and most of the timber cutters belonged to the class ”exceptionally active”.

The PDF includes an abstract in Finnish.

  • Saarilahti, ORCID ID:E-mail:
  • Bakena, ORCID ID:E-mail:
  • Mboya, ORCID ID:E-mail:
  • Minja, ORCID ID:E-mail:
  • Ngerageze, ORCID ID:E-mail:
  • Ntahompagaze, ORCID ID:E-mail:
article id 5313, category Article
Pentti Lähteenoja. (1987). Metsänomistajien tavoitteellisen ryhmäneuvonnan vaikuttavuus. Silva Fennica vol. 21 no. 2 article id 5313.
English title: Effects of forestry extension courses.

The attitudinal, behavioural and cognitive effects of four forestry extension and training courses were evaluated. The courses produced positive effects on the participants’ forestry knowledge. Further new forestry skills were adopted, and the courses had some positive behavioural effects. The attitudinal effects of the courses were mainly inconclusive. Differences between the evaluated courses were remarkable.

The PDF includes an abstract in Finnish.

  • Lähteenoja, ORCID ID:E-mail:
article id 5312, category Article
Timo Pukkala. (1987). Siementuotannon vaikutus kuusen ja männyn vuotuiseen kasvuun. Silva Fennica vol. 21 no. 2 article id 5312.
English title: Effect of seed production on the annual growth of Picea abies and Pinus sylvestris.

The study material consisted of 13 rather old Norway spruce (Picea abies (L.) H. Karst.) and 17 Scots pine (Pinus sylvestris L.) stands located in different parts of Finland. In each stand the seed crops, radial growth and amount of latewood were measured during a period of about ten years. Seed production reduces the radial growth of spruce and pine in the year of seed maturing. In Southern and Central Finland also the proportion of latewood is reduced. Seed production accounts for about 14% of the variation in radial growth of a spruce stand growing in Lapland, and 27% in other parts of Finland. In pine stands the seed crop explains 19% of the variation in radial growth in Lapland, and only 7% in the rest of Finland. In spruce stands an average seed crop reduces radial growth by 14% in Lapland and 5% in the rest of the country. An abundant seed production causes a reduction of about 20%. In southern parts of Finland, the proportion of latewood is reduced by 5% in an average seed year and by 24% in a good seed year. In pine stands an average seed crop decreases the width of annual ring by 5%, and a good seed crop by 15%. Outside Lapland, also the proportion of latewood is reduced: in an average seed year by 5%, and in a good seed year by 16%. The reduction in volume growth of spruce stands due to an average seed crop was estimated to be about 10% in Lapland, and 6% in other parts of Finland. A prolific seed production causes a reduction of 20%. In old pine stands the reduction is 5% in an average seed year, and 15% in a good seed year.

The PDF includes an abstract in English.

  • Pukkala, ORCID ID:E-mail:
article id 5311, category Article
Timo Pukkala. (1987). Kuusen ja männyn siemensadon ennustemalli. Silva Fennica vol. 21 no. 2 article id 5311.
English title: Model for predicting the seed crop of Picea abies and Pinus sylvestris.

The seed crop of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) is predicted with the help of mean monthly temperatures during May–August one and two years before the flowering year. The prediction models were made separately for Lapland and for the rest of Finland. The models are based on 10-year periods of seed crop measurements and climatic data. The total number of time series was 59.

In Lapland, Norway spruce flowered abundantly and produced an abundant seed crop after warm July–August and two years after cool July–August. In other parts of Finland, warm June and July produced a good flowering year, especially if these months were cool two years before the flowering year.

In Lapland, Scots pine flowered abundantly if the whole previous growing season was warm. Elsewhere in Finland, a cool June preceded prolific flowering in the coming year if the rest of the growing season was considerably warmer than the average.

The prediction models explained 37–49 % of the variation in the size of the seed crop. The occurrence of good and poor seed years was usually predicted correctly. Using the presented models, the prediction of the seed crop is obtainable 1.5 year for Norway spruce and 2.5 year for Scots pine before the year of seed fall.

The PDF includes an abstract in English.

  • Pukkala, ORCID ID:E-mail:
article id 5310, category Article
Petri Kärenlampi. (1987). Puun lahonkestävyys ja kosteusdynamiikka. Silva Fennica vol. 21 no. 2 article id 5310.
English title: The decay resistance and moisture dynamics of wood.

In laboratory studies the heartwood content seems to be the only natural property of a wood of different tree species influencing the decay resistance. Moistening and drying by diffusion happen quite slowly. Scots pine (Pinus sylvestris L.) sapwood takes moisture by capillary action quicker than pine heartwood and Norway spruce (Picea abies (L.) H. Karst.) wood. Swelling and shrinkage are also greatest in pine sapwood. Impregnation of pine sapwood can give it better hydrophobic and dimensional stability than that of pine heartwood.

The PDF includes an abstract in English.

  • Kärenlampi, ORCID ID:E-mail:
article id 5309, category Article
Veli Pohjonen. (1987). Vesipaju ja vannepaju energiapajututkimuksissa. Silva Fennica vol. 21 no. 2 article id 5309.
English title: Salix "Aquatica Gigantea" and Salix x dasyclados Wimm. in biomass willow research.

Salix 'Aquatica Gigantea', widely experimented and promising species for temperate zone short rotation forestry, has since 1950 recorded in Finland 23 times with different clone numbers. Salix x dasyclados Wimm., by morphological, cultivational and productivity characteristics similar willow has been recorded 16 times.

The nomenclature and origin of both willows have remained unclear in field research. Recent observations, based on morphological analyses and chromosome studies suggest that ’Aguatica gigantea’ and most S. x dasuclados clones can be collected under one Siberian species: Salix burjatica Nasarov. The true Salix x dasyclados Wimm. is a female hybrid S. x viminalis x cinerea, famous West-European basket willow that has been very little experimented in Finland.

The PDF includes an abstract in Finnish.

  • Pohjonen, ORCID ID:E-mail:

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