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Silva Fennica 1926-1997
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Articles containing the keyword 'shading'.

Category: Research article

article id 1734, category Research article
Jyrki Hytönen, Paula Jylhä, Keith Little. (2017). Positive effects of wood ash fertilization and weed control on the growth of Scots pine on former peat-based agricultural land – a 21-year study. Silva Fennica vol. 51 no. 3 article id 1734. https://doi.org/10.14214/sf.1734
Highlights: Weed control decreased and fertilization increased vegetation height and shading of seedlings; Weed control decreased mortality, but fertilization had no effect; Despite improved foliar K concentration though ash fertilization, all trees in the trial had severe K deficiency after 21 years; Weed control increased growth by 20 m3 ha–1 and fertilization by 35 m3 ha–1 in 21 years.

The impacts of weed control, ash fertilization and their interaction were tested for the afforestation of former agricultural peat-based soil with Scots pine (Pinus sylvestris L.) in northern Finland in a factorial arrangement of four treatments. Weed control with herbicides was carried out in July 1 and 2 years from planting, and wood ash (5 Mg ha–1) was applied in the spring of the 2nd year. Various vegetation, tree growth and nutrient assessments were made over the 21-year study period. Weed control decreased the weed cover by 36–56 percentage points, vegetation height by 4–26 cm and thus shading of seedlings by vegetation for at least 4 years after planting. For the same period, ash fertilization increased vegetation height by 6–15 cm and shading of seedlings. Weed control reduced seedling mortality by 27 percentage points in 21 years, but ash fertilization had no significant effect. Ash fertilization increased foliar potassium and boron concentrations, but its effect declined, and severe K-deficiency was recorded 21 years after planting. Up to the 9th year, weed control had a greater influence on growth than fertilization. Later the significance of fertilization increased due to an aggravated K-deficiency. Stand volume at year 21 for the untreated control plots was 8 m3 ha–1. Weed control and fertilization increased stand volume by 20 and 35 m3 ha–1, with a combined effect of 55 m3 ha–1. The effects of weed control and fertilization were additive and no significant interactions were found. Due to severe K-deficiencies, re-fertilization of all treatments would be necessary for the continued survival and growth of Scots pine.

  • Hytönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID: http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi (email)
  • Jylhä, Natural Resources Institute Finland (Luke), Green technology, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID:E-mail: paula.jylha@luke.fi
  • Little, Nelson Mandela Metropolitan University, George Campus, Western Cape, South Africa ORCID ID:E-mail: keith.little@nmmu.ac.za
article id 197, category Research article
Veli-Pekka Ikonen, Seppo Kellomäki, Heli Peltola. (2009). Sawn timber properties of Scots pine as affected by initial stand density, thinning and pruning: a simulation based approach. Silva Fennica vol. 43 no. 3 article id 197. https://doi.org/10.14214/sf.197
The aim of this work was to analyze how different management schedules with varying initial stand density, thinning and artificial pruning of branches affect the quality, quantity and value of sawing yield in Scots pine (Pinus sylvestris L.). For this purpose, an integrated model system was employed and further developed to simulate: i) the three dimensional structure of the crown and stem of an average tree grown in a stand related to the changes in the within-stand light conditions as caused by the stand management, and ii) the sawing of logs into pieces and their quality grading based on the size and number of living and dead knots on the surfaces of sawn pieces. To maximize the quality of sawn timber, relatively dense stand is desired in the early phase of the rotation to reduce, especially in the lower part of stem, the growth of branches, and to increase the rate of dying and pruning-off of branches. In the later phase, a relatively sparse stand is desired to increase the self-pruning of branches and the occlusion of knots. However, in any case, artificial pruning is needed to maximize the knot-free zone of the stem. Also the value optimization of individual sawn pieces affects the quality and value of sawn timber. Because, only average tree was simulated, the differences between scenarios for stem volume were small. In the future, further model development is needed to analyze the development of crown and stem properties of trees with different status in a stand.
  • Ikonen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: veli-pekka.ikonen@joensuu.fi (email)
  • Kellomäki, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Peltola, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:

Category: Article

article id 5414, category Article
Heikki Smolander, Seppo Kellomäki, Pauline Oker-Blom. (1990). Typpipitoisuuden vaikutus männyn neulasten fotosynteesiin ja verson itsevarjostukseen. Silva Fennica vol. 24 no. 1 article id 5414. https://doi.org/10.14214/sf.a15566
English title: The effect of nitrogen concentration on needle photosynthesis and within shoot shading in Scots pine.

A close relationship between photosynthetic capacity and nitrogen concentration of leaves is known to exist. In conifers, nitrogen also affects the pattern of mutual shading within a shoot, which is a basic unit used in studying photosynthesis of coniferous trees. These effects of needle nitrogen concentration on photosynthetic capacity and mutual shading of needles were analysed for Scots pine (Pinus sylvestris L.) shoots taken from five young stands growing on sites of different fertility. The effect of nitrogen concentration on needle photosynthesis was studied based on measurements of the photosynthetic radiation response of shoots from which two thirds of the needles were removed in order to eliminate the effect of within shading.

An increase of one percentage unit in nitrogen concentration of needles increased the photosynthetic capacity of needles by 25 mg CO2 dm-2h-1. The effect of nitrogen on within-shoot shading was quantified in terms of the silhouette area to total needle area ratio of a shoot (STAR), which determines the relative interception rate per unit of needle area on the shoot. Although nitrogen promoted needle growth, an increase in nitrogen concentration decreased the within-shoot shading. This effect resulted from a decrease in needle density on the shoot and an increased needle angle with increasing nitrogen content.

The PDF includes an abstract in Finnish.

  • Smolander, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
article id 5316, category Article
Timo Pukkala, Timo Kuuluvainen. (1987). Effect of canopy structure on the diurnal interception of direct solar radiation and photosynthesis in a tree stand. Silva Fennica vol. 21 no. 3 article id 5316. https://doi.org/10.14214/sf.a15473

The utilization of direct radiation was studied in five model stands of Poisson-type tree distribution and cone-shaped crowns. The radiation extinction depended on the self-shading of the crown and the shading caused by other trees. The results indicate that at low sun elevation a stand populated by very narrow-crowned trees is most effective in light interception and photosynthesis. At high sun elevation a broad-crowned canopy is best illuminated and most favourable for photosynthesis. A stand with a two-storey canopy is effective in all latitudes when the crowns are moderately narrow. In two-storey canopies the foliage of the lower storey can be better illuminated than in the lower parts of the upper storey, because of the smaller self-shading in the small crowns of the lower storey. A canopy where the crown volume is concentrated on few big crowns is less effective than a canopy consisting of many small crowns.

The PDF includes an abstract in Finnish.

  • Pukkala, ORCID ID:E-mail:
  • Kuuluvainen, ORCID ID:E-mail:
article id 5190, category Article
Jussi Kuusipalo. (1983). Mustikan varvuston biomassamäärän vaihtelusta erilaisissa metsiköissä. Silva Fennica vol. 17 no. 3 article id 5190. https://doi.org/10.14214/sf.a15173
English title: The distribution of blueberry biomass in different forest stands.

The study deals with the distribution of above-ground biomass of Vaccinium myrtillus L. along the vegetation continuum segregated by using phytosociological classification method composite clustering. The qualitative characteristics of forest sites corresponding to different vegetational clusters were defined on the basis of indirect gradient analysis of vegetation data and description of tree stand properties in stands in 160 sample areas in Southern Finland.

Six vegetation types differing from each other mainly in abundance of the most constant and dominant plant species were formed. Sample areas with rich grass-herb vegetation, as well as sample areas representing comparatively dry, barren site type were clearly separated from other groups of sample areas. Stand characteristics, particularly the proportional distribution of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seems to be another important factor affecting the vegetation composition.

The lowest biomass values of blueberry were connected with herb-rich vegetation and shady spruce-dominated stands. Comparatively low values were connected to also other spruce-dominated sample areas. Pine-dominant or mixed pine-spruce stands the biomass values were significantly higher. Even if the site quality is essentially equal, the abundance relationships between Vaccinium myrtillus and other components of the ground vegetation may vary in wide ranges and cause difficulties in practical site classification.

The PDF includes a summary in English.

  • Kuusipalo, ORCID ID:E-mail:
article id 5125, category Article
Ilppo Greis, Seppo Kellomäki. (1981). Crown structure and stem growth of Norway spruce undergrowth under varying shading. Silva Fennica vol. 15 no. 3 article id 5125. https://doi.org/10.14214/sf.a15066

The crown structure and stem growth of Norway spruce (Picea abies (L.) H. Karst.) undergrowth was studied in relation to the prevailing light conditions and potential photosynthesis. Shading decreased the stem height growth more than the length increment of laterals, producing a plate-shaped crown in deep shade. Needles responded to shading by adopting a horizontal inclination in deep shade. The needles were wide and thin respectively in shade. In the open the needle cross-section was almost square. Stem radial growth and height growth were both affected by shading exhibiting a linear response to the prevailing light conditions and the potential photosynthesis. Light conditions under dominating trees were closely correlated with the basal area of the dominating trees.

The PDF includes a summary in Finnish.

  • Greis, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:

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