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Articles containing the keyword 'light conditions'

Category : Article

article id 5239, category Article
Jussi Kuusipalo. (1985). On the use of tree stand parameters in estimating light conditions below the canopy. Silva Fennica vol. 19 no. 2 article id 5239. https://doi.org/10.14214/sf.a15418
Keywords: Pinus sylvestris; basal area; Picea abies; canopy; tree species composition; light conditions; light climate; number of stems; canopy coverage
Abstract | View details | Full text in PDF | Author Info

Especially in forest vegetation studies, the light climate below the canopy is of great interest. In extensive forest inventories, direct measurement of the light conditions is too time-consuming. Often only the standard tree stand parameters are available. The present study was undertaken with the aim to develop methods for estimation of the light climate on the basis of readily measurable tree stand characteristics. The study material includes 40 sample plots representing different kinds of more or less mature forest stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.).

In each forest stand, a set of hemipherical photographs was taken and standard tree stand measurements were performed. A regression approach was applied in order to elaborate linear models for predicting the canopy coverage. The total basal area of the stand explained 63% of variance in the canopy coverage computed from hemipherical photographs. A coefficient representing the relative proportion of Norway spruce in the stand increased the explanatory power into 75%. When either the stand density (stems/unit area) or dominant age of the stand was included into the model, increment of the explanatory power into 80% was achieved. By incorporating both of the preceding predictors, an explanatory power of 85% was reached.

The PDF includes a summary in Finnish.

  • Kuusipalo, E-mail: jk@mm.unknown (email)
article id 5189, category Article
Anneli Viherä, Seppo Kellomäki. (1983). Havaintoja nuorten mäntyjen latvusten hienorakenteesta ja kasvusta. Silva Fennica vol. 17 no. 3 article id 5189. https://doi.org/10.14214/sf.a15172
English title: Observations on structure and growth of crowns of young Scots pines.
Original keywords: mänty; versot; neulaset; biomassa; oksat; latvus; latvuksen rakenne; valaistusolot
English keywords: Pinus sylvestris; biomass; needles; Scots pine; branches; crown; light conditions; shoots; structure of the crown
Abstract | View details | Full text in PDF | Author Info

A study based on four young Scots pines (Pinus sylvestris L.) showed that the number of needle-covered shoots per crown volume unit was independent on tree position representing a constant value of 600–700 shoots/m3. This was true, even though the total shoot number decreased with deteriorating tree position. In tree crown there were fourth-order shoots in good light conditions but only first- and second-order-shoots, when light conditions were poor. The length of shoots decreased in accordance with increasing order of the shoot.

The share of the needle biomass and growth increased, when the shoot order increased. Similarly, the share of needles increased with deteriorating tree position. This was especially true in the upper crown. On the other hand, the share of the crown from the total biomass and growth increased with improving tree position. The percentage of crown system of a dominant tree in a sparse stand was 64% of that of biomass and 83% of that of growth. The corresponding values for a suppressed tree in a dense stand were 36% and 35%. The growth of wood, bark and needles in crown systems was linearly correlated with prevailing light conditions around the branch. It is evident that the tree position and light condition within the stand control the wood, bark and needle growth in the crown system and their interrelationships.

The PDF includes a summary in English.

  • Viherä, E-mail: av@mm.unknown (email)
  • Kellomäki, E-mail: sk@mm.unknown
article id 5116, category Article
Seppo Kellomäki, Pauline Oker-Blom. (1981). Specific needle area of Scots pine and its dependence on light conditions inside the canopy. Silva Fennica vol. 15 no. 2 article id 5116. https://doi.org/10.14214/sf.a15057
Keywords: Pinus sylvestris; needles; Scots pine; crown; crown class; light conditions; needle area
Abstract | View details | Full text in PDF | Author Info

The specific needle area of young Scots pine (Pinus sylvestris L.) showed a substantial within-tree and between-tree variation which was associated with the position of the tree and the position of the whorl as indicated by the prevailing crown and branch illumination. In suppressed trees the values of the specific needle area were three to four times those in dominating trees. A similar morphogenesis was discernible in comparison of the lower and the upper part of the crown. The mean specific needle area value for the whole stand was 184 cm2/g.

The PDF includes a summary in Finnish.

  • Kellomäki, E-mail: sk@mm.unknown (email)
  • Oker-Blom, E-mail: po@mm.unknown
article id 5111, category Article
Seppo Kellomäki. (1981). Effect of the within-stand light conditions on the share of stem, branch and needle growth in a twenty-year-old Scots pine stand. Silva Fennica vol. 15 no. 2 article id 5111. https://doi.org/10.14214/sf.a15052
Keywords: Pinus sylvestris; Scots pine; growth; stand density; branches; stems; light conditions
Abstract | View details | Full text in PDF | Author Info

The share of stem, branch and needle growth was dependent on the within-stand light regime in a young Scots pine (Pinus sylvestris L.) stand. The share of needle growth increased at the expense of stem and branch growth in poor light conditions. In good light condition the share of branch wood increased substantially. The share of stem wood growth was greatest in moderate shading, emphasizing the role of an adequate stand density for growing high-quality timber. The basic density of the stem wood was considerably greater in suppressed trees than in dominating trees. The differences were related to the illumination of the crown system.

The PDF includes a summary in Finnish.

  • Kellomäki, E-mail: sk@mm.unknown (email)
article id 5092, category Article
Seppo Kellomäki, Markku Kanninen. (1980). Eco-physiological studies on young Scots pine stands. IV. Silva Fennica vol. 14 no. 4 article id 5092. https://doi.org/10.14214/sf.a15033
Keywords: Pinus sylvestris; Scots pine; height growth; radial growth; basic density; crown; photosynthate supply; light conditions
Abstract | View details | Full text in PDF | Author Info

Crown and stem growth of young Scots pines (Pinus sylvestris L.) were studied in relation to photosynthate supply and light condition in a stand. The magnitude of needle and bud formation, and radial and height growth were to a great extent dependent on the photosynthate supply. However, in shaded conditions the growth of each characteristics was greater than expected on the basis of photosynthate supply. In the stem system this was especially apparent for height growth. Consequently, height growth was favoured at the expense of radial growth in shaded conditions. It also appeared that the basic density of wood was negatively related to both tree position and photosynthate supply.

The PDF includes a summary in Finnish.

  • Kellomäki, E-mail: sk@mm.unknown (email)
  • Kanninen, E-mail: mk@mm.unknown

Category : Article

article id 7624, category Article
Pertti Hari, Seppo Kellomäki, Annikki Mäkelä, Pirkko Ilonen, Markku Kanninen, Eeva Korpilahti, Markku Nygren. (1982). Metsikön varhaiskehityksen dynamiikka. Acta Forestalia Fennica no. 177 article id 7624. https://doi.org/10.14214/aff.7624
English title: Dynamics of early development of tree stand.
Original keywords: tiheys; mänty; metsikön rakenne; metsikön kehitys; valo-olosuhteet; yhteyttäminen
English keywords: Pinus sylvestris; stand structure; photosynthesis; Scots pine; density; stand development; light conditions
Abstract | View details | Full text in PDF | Author Info

The report concludes a series of studies on the early development of young Scots pine (Pinus sylvestris L.) stands. The basis assumption made in the study series was that the within-stand light regime is the main driving force for total tree growth and its allocation of photosynthates for crown, stem and root growth. An individual tree growing in a stand under a varying light regime which is controlled by the stand structure, is the basic unit used in the study. The photosynthesis of an individual tree is determined by the light regime. The stand is formed from individual trees.

The model is applied in simulation of the growth and development of tree stands. Several computer runs representing various densities, height distributions and tree species mixtures were carried out. Potential application areas, properties of the model and future needs of investigations are discussed.

The PDF includes a summary in English.

  • Hari, E-mail: ph@mm.unknown (email)
  • Kellomäki, E-mail: sk@mm.unknown
  • Mäkelä, E-mail: am@mm.unknown
  • Ilonen, E-mail: pi@mm.unknown
  • Kanninen, E-mail: mk@mm.unknown
  • Korpilahti, E-mail: ek@mm.unknown
  • Nygren, E-mail: mn@mm.unknown

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