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Acta Forestalia Fennica
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Articles containing the keyword 'knottiness'

Category: Article

article id 5266, category Article
Matti Kärkkäinen. (1986). Malli männyn, kuusen ja koivun puuaineen oksaisuudesta. Silva Fennica vol. 20 no. 2 article id 5266. https://doi.org/10.14214/sf.a15445
English title: Model of knottiness of wood material in pine, spruce and birch.
Original keywords: kuusi; mänty; oksaisuus; rauduskoivu; hieskoivu; simulointi; aihion poikkileikkaus; puutavaran laatu
English keywords: Pinus sylvestris; Norway spruce; birch; Betula; Picea abies; Scots pine; simulation; knots; timber quality; knottiness
Abstract | View details | Full text in PDF | Author Info

A computer model was developed for predicting knottiness of wood material of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula sp). The prediction included location of knots, their size and quality, i.e. if they are dead or living knots. The model suits best for tree species where branches are born at the base of shoots, in Finland such tree species is Scots pine.

The usefulness of the model was tested in the prediction of knots in wooden elements of joinery industry. According to the results, the shape of cross section affects the surface quality of elements. Especially useful is a quadratic cross section as it increases the probability to get a knotless surface.

The PDF includes an abstract in English.

  • Kärkkäinen, E-mail: mk@mm.unknown (email)
article id 5246, category Article
Matti Kärkkäinen, Markku Halinen. (1985). Mäntysahatukkien minimivaatimusten täsmentäminen. Silva Fennica vol. 19 no. 3 article id 5246. https://doi.org/10.14214/sf.a15425
English title: Reappraisal of minimum requirements of Scots pine saw logs.
Original keywords: mänty; sahatavara; oksaisuus; laatuvaatimukset; kuivien oksien läpimitta; mäntysahatukki
English keywords: Pinus sylvestris; Scots pine; saw logs; sawlog quality; knottiness; quality classification; sawn goods; diameter of dry knots
Abstract | View details | Full text in PDF | Author Info

A test sawing was made of 807 Scots pine (Pinus sylvestris L.) saw logs of varying size and quality. The most important knot characteristic affecting the value of sawn goods was the diameter of the thickest dry knot. The new minimum requirements for pine logs were proposed on the basis of top diameter of the log and the diameter of the thickest dry and living knot.

The PDF includes a summary in English

  • Kärkkäinen, E-mail: mk@mm.unknown (email)
  • Halinen, E-mail: mh@mm.unknown
article id 4760, category Article
Veijo Heiskanen. (1968). Kuusitukkien laatuluokkajakautuma Etelä-Suomessa. Silva Fennica vol. 2 no. 1 article id 4760. https://doi.org/10.14214/sf.a14544
English title: Grade distribution of Norway spruce logs in Southern Finland.
Original keywords: kuusi; laatuluokitus; tukki; tyvitukki; latvatukki; vikaisuus; kuusitukki; oksaisuus; mutkaisuus
English keywords: Norway spruce; saw logs; knottiness; quality grading; butt log; top log; defects; crooks
Abstract | View details | Full text in PDF | Author Info

The aim of the present study was to find the factors influencing the distribution of Norway spruce (Picea abies (L.) H. Karst.) logs on various grades with special stress on the effects of the grade on the value of logs. The material was obtained from ten sawmills located in Southern Finland by grading a total of 13,559 logs.

The results showed that knottiness in its different forms of appearance is the most important factor influencing the quality of spruce logs. Its significance is clearly greater in spruce than in Scots pine saw logs. Among the other defects, the most common are crooks. Even scars and decay occur to a considerable degree, but other defects seldom affect the grade. The quality of butt logs is markedly better than that of top logs. Both in butt and top logs the smallest logs in diameter are of poorer quality. However, in the largest diameter classes the quality begins again to decrease.

The difference in the quality of logs of the same grade at various sawmills is very small. The results of grading at varying times at the same sawmill show greater differences than can be observed between different sawmills. However, the logs of sawmills that procure the timber from coastal areas and islands are inferior to those which procure the timber from the mainland.

The PDF includes a summary in English.

  • Heiskanen, E-mail: vh@mm.unknown (email)
article id 4516, category Article
M. Lappi-Seppälä. (1937). Karsimisesta arvopuun kasvatusta silmällä pitäen. Silva Fennica vol. no. 42 article id 4516. https://doi.org/10.14214/sf.a14094
English title: Pruning as a means to produce quality timber.
Original keywords: metsäopetus; metsänhoitajien jatkokurssit; karsiminen; laatupuu; oksikkuus; pystykarsinta
English keywords: pruning; timber quality; forest education; professional development courses; branchiness; knottiness
Abstract | View details | Full text in PDF | Author Info

Silva Fennica issue 42 includes presentations held in professional development courses, arranged for foresters working in public administration in 1936. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service

This presentation describes how pruning is used to produce quality timber.

  • Lappi-Seppälä, E-mail: ml@mm.unknown (email)

Category: Article

article id 7164, category Article
Veijo Heiskanen. (1965). Puiden paksuuden ja nuoruuden kehityksen sekä oksaisuuden ja sahapuulaadun välisistä suhteista männiköissä. Silva Fennica vol. 80 no. 2 article id 7164. https://doi.org/10.14214/aff.7164
English title: Relation between the development of the early age and thickness of trees and their branchiness in Scots pine stands in Finland.
Original keywords: tiheys; mänty; laatupuu; tyvitukki; oksaisuus; kasvatustiheys; laatukasvatus
English keywords: Pinus sylvestris; Scots pine; density; quality; stand density; branchiness; knottiness; butt log; quality timber
Abstract | View details | Full text in PDF | Author Info

The objective of the study was to establish the influence of the founding density of a stand and the intensity of intermediate cutting on the quality of pine saw logs stems, primarily on their branchiness. Measurements were carried out in 68 Myrtillus-type and 32 Vaccinium-type Scots pine (Pinus sylvestris L.) stands. The quality of 1,982 sample trees was assessed.

According to the results, the branchless part of the stem is longest in the older age classes of trees. In all age classes the percentage of the branchless part is highest in medium sized stems. The relative height of the crown limit is greatest in small diameter classes and continues as the thickness of the tree increases. The crown is longer in the thicker tree. The grade of the butt log is on average highest in medium sized stems. Knottiness of a log made it unsuitable for a saw log only among the thickest stems. The relative share of the u/s grade decreased as the thickness of the trees increased.

From the point of view of early development of the trees it was concluded that in all age classes the branchless part is the shorter the faster the tree has grown in diameter when it was young. Also, branches of the butt log are the bigger the faster the tree has developed when it was young. The grade of the butt log improves as the thickness of the annual rings diminishes.

To produce good quality sawn timber, the pine stands should be established dense, and the first thinnings should be delayed as much as possible. The best time for the thinning would be when the diameter of the dominant trees at stump height is 12–15 cm and when all the branches have died on the length of the butt log. After the first thinning, comparatively intense intermediate thinning may be applied.

The PDF includes a summary in English.

  • Heiskanen, E-mail: vh@mm.unknown (email)
article id 7317, category Article
Erkki Laitakari. (1935). Tutkimuksia metsikön ja kasvupaikan vaikutuksesta kuusen rungon kelpoisuuteen. Silva Fennica vol. 41 no. 4 article id 7317. https://doi.org/10.14214/aff.7317
English title: Studies on the influence of stand and forest site type on the quality of Norway spruce stem.
Original keywords: kuusi; Picea abies; laatupuu; oksikkuus; rungon laatu
English keywords: branchiness; knottiness; quality timber; quality of wood
Abstract | View details | Full text in PDF | Author Info

Healthy, straight, more or less free from branches and slowly tapering stems are good raw material for woodworking industry. The aim of the study was to investigate, from the stand point of forest management, the influence of stand and forest site type on the technical quality of the stems. Sample plots were measured in Norway spruce (Picea abies (L.) H. Karst.) stands in Eastern Finland. Norway spruce growing in a stand with closed crowns developed thin branches and self-pruned, if the stand was dense in the early stages. The decisive time for the stand is, therefore, when it is at seedling stage and young stand. The stems are more branchy if the stand has been planted. The adequate planting density is discussed based on earlier studies. The sufficient density seems to be achieved when the spacing is at maximum two meters. When the stems are branchless up to four meters, thinning of spruce stand does not affect knottiness or stem form. A sparsely stocked, knotty young stand does not produce good-quality timber even if the stand is later dense. Selective thinning from above can be used to improve the quality of the wood.

The PDF includes a summary in German.

  • Laitakari, E-mail: el@mm.unknown (email)
article id 7302, category Article
M. Lappi-Seppälä. (1934). Karsimisesta ja sen metsänhoidollisesta merkityksestä. Silva Fennica vol. 40 no. 25 article id 7302. https://doi.org/10.14214/aff.7302
English title: The silvicultural influences of pruning.
Original keywords: puutavara; karsiminen; oksaton; vaneritukki; tukin laatu
English keywords: timber quality; tree growth; knottiness; value of timber
Abstract | View details | Full text in PDF | Author Info

Pruning growing trees influences tree growth and value of the wood and yield of timber of the stand. Pruning living branches create open wounds on the stems that can risk the growth of tree species that are vulnerable to injuries. For instance, pruning has been shown to cause decay in Norway spruce (Picea abies (L.) H. Karst.), while Scots pine (Pinus sylvestris L.) can quickly heal over the branch scars. Pruning of living branches reduces the crown, the effect of which remains small if only the lowest branches are pruned. Pruning of dry branches has little effect on the health of the tree. The main objective of pruning is to improve the quality of timber. Knottiness decreases strength and appearance of timber. Pruning increases the yield of knot-free sapwood, which is especially valuable in veneer timber. Pruning is, therefore, at present most suitable for birch and aspen which are used in veneer industry. In both species pruning should be directed mainly to dry branches.

The PDF includes a summary in German.

  • Lappi-Seppälä, E-mail: ml@mm.unknown (email)

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