Current issue: 53(3)

Under compilation: 53(4)

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Articles containing the keyword 'light'.

Category: Research article

article id 7710, category Research article
Pekka Hyvönen, Jaakko Heinonen. (2018). Estimating storm damage with the help of low-altitude photographs and different sampling designs and estimators. Silva Fennica vol. 52 no. 3 article id 7710. https://doi.org/10.14214/sf.7710
Highlights: Digital photographs taken from low altitudes are usable for monitoring storm damage; Simple random sampling and ratio estimators resulted in similar standard errors; Characteristics of the storm influence the optimal flight plan and which variance estimator should be used; The developed model for simulations can be modified and utilized with future storms.

Climate change has been estimated to increase the risk of storm damage in forests in Finland. There is a growing need for methods to obtain information on the extent and severity of storm damage after a storm occurrence. The first objective of this study was to test whether digital photographs taken from aircrafts flying at low-altitude can be utilized in locating storm-damaged areas and estimating the need for harvesting of wind-thrown trees. The second objective was to test the performance of selected estimators. Depending on distances between flight lines, plots on lines and the used estimator, the relative standard errors of storm area estimates varied between 7.7 and 48.7%. For the area for harvesting and volume of wind-thrown trees, the relative standard errors of estimates varied between 16.8 and 167.3%. Using forest area information from Multisource National Forest Inventory data improved the accuracy of the estimates. However, performance of a simple random sampling estimator and ratio estimator were quite similar. Lindeberg’s method for variance estimation based on adjacent lines was sensitive to line directions in relation to possible trends in storm-damaged area locations. Our results showed that the tested method could be used in estimating storm-damaged area provided that the network of flight lines and photographs on lines are sufficiently dense. The developed model for simulations can be utilized also with forthcoming storms as model’s parameters can be freely adjusted to meet, e.g., the intensity and extent of the storm.

  • Hyvönen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: pekka.hyvonen@luke.fi (email)
  • Heinonen, ORCID ID:E-mail: jaakkoheinonen@gmail.com
article id 1239, category Research article
Tomi Kaakkurivaara, Nuutti Vuorimies, Pauli Kolisoja, Jori Uusitalo. (2015). Applicability of portable tools in assessing the bearing capacity of forest roads. Silva Fennica vol. 49 no. 2 article id 1239. https://doi.org/10.14214/sf.1239
Highlights: The dynamic cone penetrometer (DCP) and light falling weight deflectometer (LFWD) are useful tools for measuring bearing capacity; The measurement results are not same as with the falling weight deflectometer (FWD), but comparable.
Forest roads provide access to logging sites and enable transportation of timber from forest to mills. Efficient forest management and forest industry are impossible without a proper forest road network. The bearing capacity of forest roads varies significantly by weather conditions and seasons since they are generally made of poor materials and the constructed layers may be mixed with subgrade. A bearing capacity assessment is valuable information when trafficability is uncertain and rutting is obvious. In this study, bearing capacity measurements were carried out using the light falling weight deflectometer (LFWD), the dynamic cone penetrometer (DCP) and the conventional falling weight deflectometer (FWD). The aim was to compare their measurement results in relation to road characteristics and moisture conditions. Data were collected from 35 test road sections in four consecutive springs and during one summer. The test road sections had measurement points both on the wheel path and the centre line. The data show logical correlations between measured quantities, and the study presents reliable regression models between measuring devices. The results indicate that light portable tools, the DCP and the LFWD, can in most cases be used instead of the expensive falling weight deflectometer on forest roads.
  • Kaakkurivaara, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: tomi.kaakkurivaara@gmail.com (email)
  • Vuorimies, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland ORCID ID:E-mail: nuutti.vuorimies@tut.fi
  • Kolisoja, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland ORCID ID:E-mail: pauli.kolisoja@tut.fi
  • Uusitalo, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland ORCID ID:E-mail: jori.uusitalo@luke.fi
article id 95, category Research article
Venceslas Goudiaby, Suzanne Brais, Yvon Grenier, Frank Berninger. (2011). Thinning effects on jack pine and black spruce photosynthesis in eastern boreal forests of Canada. Silva Fennica vol. 45 no. 4 article id 95. https://doi.org/10.14214/sf.95
A decrease in the average diameter of commercially harvested tree species in the Eastern boreal forest of Canada has led to a decrease in availability of quality wood for the forest industry. Commercial thinning has been proposed as a means to increase stem diameter growth. However, little is known about physiological responses underlying species responses to thinning. We assessed the effect of canopy opening on the photosynthetic response of mature jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) trees. Two years after thinning and for each species, light response curves and the diurnal course of photosynthesis were characterized from measurements taken in a completely randomized block experiment on current-year and one-year-old needles of 12 trees from stands subjected to different levels of canopy opening. Soil water content, air and soil temperatures, and needle N concentration were not affected by thinning for either species. However, light availability increased with basal area removed and could explain the significantly positive relationship between thinning intensity and diurnal course of photosynthesis for one-year-old needles of jack pine. Black spruce photosynthesis did not respond to increases in light. Light-saturated rate of net photosynthesis (Amax), photosynthetic efficiency (α), light compensation point (LCP), and diurnal respiration (Rd) did not vary with thinning for either of the species. Jack pine and black spruce responses to thinning should be interpreted in light of species autecology.
  • Goudiaby, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada ORCID ID:E-mail: venceslas.goudiaby@uqat.ca (email)
  • Brais, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada ORCID ID:E-mail:
  • Grenier, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada ORCID ID:E-mail:
  • Berninger, University of Helsinki, Faculty of Agriculture and Forestry, Department of Forest Sciences, Finland ORCID ID:E-mail:
article id 330, category Research article
Benoit Lapointe, Robert Bradley, William Parsons, Suzanne Brais. (2006). Nutrient and light availability to white spruce seedlings in partial and clearcut harvested aspen stands. Silva Fennica vol. 40 no. 3 article id 330. https://doi.org/10.14214/sf.330
White spruce is a commercially important tree species in Canada’s boreal forest, and studies are underway to determine the best conditions for planting nursery grown seedlings in the field. Here, we studied effects of low thinning (1/3 harvested), shelterwood (2/3 harvested), and clear-cut harvesting on soil chemical properties, on the growth and nutrition of white spruce seedlings, and on diffuse non-intercepted (DIFN) light levels at 75 cm above the soil surface. The study was conducted on a nutrient-rich clayey soil in the Abitibi region of Québec. DIFN light was lowest in non-harvested control plots and increased curvilinearly with basal area removal. Thus, DIFN light in clear-cut plots was more than twice the amount in shelterwood plots. At three years post-planting, significant linear relationships were found between DIFN light and seedling growth parameters, which were significantly higher in clear-cut than in other treatment plots. Harvesting treatments had no significant effects on soil chemical properties or on four indices of mineral N availability. Needle mass increased with harvesting intensity. Mg and K concentrations in current-year needles were lower in clear-cut than in other treatment plots. In previous-year needles, Ca concentration was higher and Mg concentrations lower in clear-cut plots, whereas as K concentration was higher in non-harvested control plots. Nutrient concentrations were nearly all sufficient in all harvesting treatments according to diagnostic norms established for white spruce. Relative nutrient content (mg nutrient needle–1) of current-year late-summer needles increased, whereas relative nutrient concentration (mg nutrient mg–1 needle) varied slightly, with increasing harvesting intensity, indicating that all nutrients were sufficient in all treatments. There were significant linear relationships between seedling growth and needle Ca, Mg and K concentrations. We conclude that light availability, rather than nutrient limitations, is the main determinant of white spruce seedling growth on these fertile soils.
  • Lapointe, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 ORCID ID:E-mail:
  • Bradley, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 ORCID ID:E-mail: robert.bradley@usherbrooke.ca (email)
  • Parsons, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 ORCID ID:E-mail:
  • Brais, UQAT, 445 boulevard Université, Rouyn-Noranda, QC, Canada J9X 5E4 ORCID ID:E-mail:
article id 404, category Research article
William L. Mason, Colin Edwards, Sophie E. Hale. (2004). Survival and early seedling growth of conifers with different shade tolerance in a Sitka spruce spacing trial and relationship to understorey light climate. Silva Fennica vol. 38 no. 4 article id 404. https://doi.org/10.14214/sf.404
Alternative silvicultural systems to clearfelling are being adopted in Great Britain as a means of increasing the species and structural diversity of conifer plantation forests. One area where knowledge is lacking is the critical level of below-canopy light for survival and growth of young seedlings. This was investigated by planting seedlings of European larch Larix decidua (Mill.), Scots pine Pinus sylvestris L., Sitka spruce Picea sitchensis (Bong.(Carr.)), Douglas fir Pseudotsuga menziesii (Mirb.(Franco.)), and western hemlock Tsuga heterophylla (Raf. (Sarg.)) in a Sitka spruce plantation thinned to 3 different spacings. The incident light intensity beneath the canopy ranged from about 2 to over 60 per cent of full light. Planting in an adjoining open area provided an indication of growth under full light. Growth and survival of these seedlings were followed for 4 growing seasons. The highest seedling survival was found under the widest spacing and declined with closer spacing and lower light intensity. Only Douglas fir and western hemlock seedlings survived at the closest spacing, and in low percentages. The tallest seedlings of each species were found in the open grown conditions but survival was variable due to increased weed competition. Species-specific growth responses showed little difference under high light conditions but performance at low light was generally consistent with shade tolerance rankings in the literature except that Sitka spruce shade tolerance was slightly lower than expected. Minimum light requirements for these species increased from 10 to 30 per cent of full light with decreasing shade tolerance. Other studies of incident light in Sitka spruce plantations indicated that target basal areas in the range 25–30 m2 ha–1 are required if these light conditions are to be met, which suggests an irregular shelterwood system with frequent interventions should be favoured.
  • Mason, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY ORCID ID:E-mail: bill.mason@forestry.gsi.gov.uk (email)
  • Edwards, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY ORCID ID:E-mail:
  • Hale, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY ORCID ID:E-mail:
article id 426, category Research article
Uwe Schmitt, Risto Jalkanen, Dieter Eckstein. (2004). Cambium dynamics of Pinus sylvestris and Betula spp. in the northern boreal forest in Finland. Silva Fennica vol. 38 no. 2 article id 426. https://doi.org/10.14214/sf.426
Wood formation dynamics of pine and birch along a south-north transect in Finnish Lapland were determined by the pinning technique. For all trees at all sites a more or less sigmoid shape of the wood formation intensity is characteristic with a slow beginning, a faster growth in the middle and a decreasing activity towards the end of the vegetation period. Wood formation of pine started at sites 1–3 (southern sites) in the second week of June and at sites 4 and 5 (northern sites) only in the last week of June, whereas wood formation ended within the first half of August. Wood formation of birch started in the second half of June and ended around the beginning of August. First cells were laid down by pine and birch when the temperature sum had reached the level of 85 to 90 degree days and 110 to 120 degree days, respectively. The intensity of wood formation in pine was highest in July, in birch within two weeks in the middle of July. Wood formation in pine lasted for about seven weeks at the southernmost and about six weeks at the northernmost site. In birch, the duration of wood formation was about five weeks at the southernmost site and around three weeks at the other sites.
  • Schmitt, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany ORCID ID:E-mail: u.schmitt@holz.uni-hamburg.de (email)
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Station, Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Eckstein, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany ORCID ID:E-mail:

Category: Review article

article id 147, category Review article
Arja Lilja, Marja Poteri, Raija-Liisa Petäistö, Risto Rikala, Timo Kurkela, Risto Kasanen. (2010). Fungal diseases in forest nurseries in Finland. Silva Fennica vol. 44 no. 3 article id 147. https://doi.org/10.14214/sf.147
Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver birch (Betula pendula) are the major tree species grown in Finnish forest nurseries where 99% of the seedlings are grown in containers first in plastic-covered greenhouses and later outdoors. The main diseases on conifer seedlings are Scleroderris canker (Gremmeniella abietina), Sirococcus blight and cankers (Sirococcus conigenum), snow blights (Herpotrichia juniperi and Phacidium infestans) and needle casts (Lophodermium seditiosum and Meria laricis). Also grey mould (Botrytis cinerea) and birch rust (Melampsoridium betulinum) are among the diseases to be controlled with fungicides. During last years Scleroderris canker has been a problem on Norway spruce, which has been since 2000 the most common species produced in Finnish nurseries. Root die-back (uninucleate Rhizoctonia sp.) on container-grown spruce and pine was a problem in the 1990s. Today the disease has become less common in modern nurseries due to improvements in hygiene and cultivation practice. Since 1991 stem lesions and top dying caused by Phytophthora cactorum has been a problem on birch. The ongoing climate change has already had effect on rusts and powdery mildews as well as other fungi infecting leaves. All diseases, which gain high precipitation and warm and long autumns. For same reasons winter stored seedlings need sprayings against grey mold. Fungal infections are also possible during short-day (SD) treatment, that is necessary for summer and autumn plantings and a beneficial step prior freezing temperatures outside or in freezer storage. Growers are encouraged to use cultural and integrated pest management techniques such as better nursery hygiene, including removing plant debris in nursery growing areas and hot water washing of containers plus removal of diseased, spore-producing seedlings and trees around the nursery.
  • Lilja, Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail: arja.lilja@metla.fi (email)
  • Poteri, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
  • Petäistö, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
  • Rikala, Finnish Forest Research Institute, Suonenjoki, Finland ORCID ID:E-mail:
  • Kurkela, Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail:
  • Kasanen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland ORCID ID:E-mail:

Category: Research note

article id 401, category Research note
Kari Taulavuori, Marian Sarala, Jouni Karhu, Erja Taulavuori, Eero Kubin, Kari Laine, Jarmo Poikolainen, Erkki Pesonen. (2005). Elongation of Scots pine seedlings under blue light depletion. Silva Fennica vol. 39 no. 1 article id 401. https://doi.org/10.14214/sf.401
The effect of blue light (400–500 nm) removal on the elongation of Scots pine (Pinus sylvetris L.) seedlings was investigated in a field experiment in Northern Finland during two growing seasons. The seedlings were grown in plexiglass chambers and ambient control plots. The blue wavelengths were removed from the light spectrum by using chambers made of orange plexiglass. The results of nearly daily measurements showed that the elongation of Scots pine seedlings was increased by the removal of blue light only at high latitudes.
  • Taulavuori, Department of Biology, University of Oulu, PO Box 3000, FI-90014, Oulu, Finland ORCID ID:E-mail: ktaulavu@cc.oulu.fi (email)
  • Sarala, Department of Biology, University of Oulu, PO Box 3000, FI-90014, Oulu, Finland ORCID ID:E-mail:
  • Karhu, Muhos Research Station, Finnish Forest Research Institute, Kirkkosaarentie 7, FI-91500 Muhos, Finland ORCID ID:E-mail:
  • Taulavuori, Department of Biology, University of Oulu, PO Box 3000, FI-90014, Oulu, Finland ORCID ID:E-mail:
  • Kubin, Muhos Research Station, Finnish Forest Research Institute, Kirkkosaarentie 7, FI-91500 Muhos, Finland ORCID ID:E-mail:
  • Laine, Department of Biology, University of Oulu, PO Box 3000, FI-90014, Oulu, Finland ORCID ID:E-mail:
  • Poikolainen, Muhos Research Station, Finnish Forest Research Institute, Kirkkosaarentie 7, FI-91500 Muhos, Finland ORCID ID:E-mail:
  • Pesonen, Vantaa Research Centre, Finnish Forest Research Institute, PO Box 18, FI-01301, Vantaa, Finland ORCID ID:E-mail:

Category: Article

article id 7298, category Article
V. T. Aaltonen. (1934). Die Entwicklung des Waldbestandes und die Wachstumsfaktoren. Acta Forestalia Fennica vol. 40 no. 21 article id 7298. https://doi.org/10.14214/aff.7298
English title: The development of a forest stand and the growth factors.

Water and amount of light are the most important growth factors and the article discusses their relationship. It is knows that the more space is needed by a tree the worse the site is. The number of stems varies between tree species. Common understanding is that amount of light is decisive to self-thinning and regeneration of a stand. On a good site the adequacy of water may substitute the lack of light. However, the fertility of soil and moisture content is more important than light.

The question of the importance of light, soil fertility and water content, as well as their relationship is important when optimizing the forest management.       

The PDF contains a summary in Finnish.  

  • Aaltonen, ORCID ID:E-mail:
article id 7238, category Article
J. Keränen. (1929). Blitzschlag als Zünder der Waldbrände im nördlichen Finnland. Acta Forestalia Fennica vol. 34 no. 25 article id 7238. https://doi.org/10.14214/aff.7238
English title: Stroke of lightning as the kindler of forest fires in northern Finland.

Earlier studies have shown strokes of lightning as the reason for 42% of forest fires in Finland. The frequency in northern Finland has been three times higher than in more southern parts of the country or 1.5 times higher than in Sweden. Taking the climatic factors into account these figures don’t seem to be accurate.

The study is based on the statistics about thunders in northern Finland and the information on the forest fires. We know that though there has been a lightning it is not always that the lighting strikes on land and lights a fire.

From the statistics it can be seen that the most forest fires that are thought to be kindled by lightning, have occurred in the same time when there has been thunder and lighting. Thunders and strokes of lightning striking to the land are the most common reason for forest fires during the warmest summer in northern Finland. The knowledge that a proceeding thunder storm may kindle several forest fires in a row must be acknowledged when planning the fire fighting resources. 

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

  • Keränen, ORCID ID:E-mail:
article id 5611, category Article
Arja Lilja, Timo Kurkela, Sakari Lilja, Risto Rikala.. (1997). Nursery practices and management of fungal diseases in forest nurseries in Finland. A review. Silva Fennica vol. 31 no. 1 article id 5611. https://doi.org/10.14214/sf.a8512

The purpose of this article was to collate the literature on fungal diseases that occur on seedlings in forest nurseries. It describes the symptoms of the diseases, the infection pattern of each fungus and the possibilities of controlling the diseases. As background a short introduction is given on forests and nursery practices in Finland.

  • Lilja, ORCID ID:E-mail:
  • Kurkela, ORCID ID:E-mail:
  • Lilja, ORCID ID:E-mail:
  • Rikala., ORCID ID:E-mail:
article id 5549, category Article
Kari Leinonen, Hannu Rita. (1995). Interaction of prechilling, temperature, osmotic stress, and light in Picea abies seed germination. Silva Fennica vol. 29 no. 2 article id 5549. https://doi.org/10.14214/sf.a9200

A multi-factor experimental approach and proportional odds model were used to study interactions between five environmental factors significant to Norway spruce (Picea abies (L.) H. Karst.) seed germination: prechilling (at +4.5°C), suboptimal temperatures (+12 and +16°C), osmotically induced water stress (0.3 Mpa and 0 Mpa), prolonged white light, and short-period of far-red light. Temperature and osmotic stress interacted with one another in the germination of seeds; the effect off osmotic stress being stronger at +16°C than at +12°C. In natural conditions, this interaction may prevent germination early in the summer when soil dries and temperature increases. Prolonged white light prevented germination at low temperature and low osmotic potential. Inhibitory effect was less at higher temperatures and higher osmotic potential, as well as after prechilling. Short-period far-red light did not prevent germination of unchilled seeds in darkness. Prechilling tended to make seeds sensitive to short pulses of far-red light, an effect which depended on temperature: at +12°C the effect on germination was promotive, but at +16°C, inhibitory and partly reversible by white light. It seems that Norway spruce seeds may have adapted to germinate in canopy shade light rich in far-red. The seeds may also have evolved mechanisms to inhibit germination in prolonged light.

  • Leinonen, ORCID ID:E-mail:
  • Rita, ORCID ID:E-mail:
article id 5549, category Article
Kari Leinonen, Hannu Rita. (1995). Interaction of prechilling, temperature, osmotic stress, and light in Picea abies seed germination. Silva Fennica vol. 29 no. 2 article id 5549. https://doi.org/10.14214/sf.a9200

A multi-factor experimental approach and proportional odds model were used to study interactions between five environmental factors significant to Norway spruce (Picea abies (L.) H. Karst.) seed germination: prechilling (at +4.5°C), suboptimal temperatures (+12 and +16°C), osmotically induced water stress (0.3 Mpa and 0 Mpa), prolonged white light, and short-period of far-red light. Temperature and osmotic stress interacted with one another in the germination of seeds; the effect off osmotic stress being stronger at +16°C than at +12°C. In natural conditions, this interaction may prevent germination early in the summer when soil dries and temperature increases. Prolonged white light prevented germination at low temperature and low osmotic potential. Inhibitory effect was less at higher temperatures and higher osmotic potential, as well as after prechilling. Short-period far-red light did not prevent germination of unchilled seeds in darkness. Prechilling tended to make seeds sensitive to short pulses of far-red light, an effect which depended on temperature: at +12°C the effect on germination was promotive, but at +16°C, inhibitory and partly reversible by white light. It seems that Norway spruce seeds may have adapted to germinate in canopy shade light rich in far-red. The seeds may also have evolved mechanisms to inhibit germination in prolonged light.

  • Leinonen, ORCID ID:E-mail:
  • Rita, ORCID ID:E-mail:
article id 5452, category Article
Riitta Höyhtyä, Heikki Hänninen. (1991). Effect of photon flux density on bud dormancy release in Norway spruce seedlings. Silva Fennica vol. 25 no. 3 article id 5452. https://doi.org/10.14214/sf.a15610

The effect of photon flux density on bud dormancy release in two-year-old seedlings of Norway spruce (Picea abies (L.) H. Karst.) was examined. The seedlings were first chilled for 0–21 weeks under natural conditions and then forced in a warm greenhouse either in low (15 μEm-2s-1) or in high (300 μEm-2s-1) photon flux density. Occurrence of bud burst was observed in the forcing conditions, and the observations were used for estimating the cumulative frequency distribution of the chilling requirement for growth competence. The estimated distribution had greater variance in the low photon flux density than in the high photon flux density forcing. This finding suggests that unnaturally low photon flux densities during forcing may yield overestimates of the genetic within-population variation in the chilling requirement for growth competence.

The PDF includes an abstract in Finnish.

  • Höyhtyä, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
article id 5427, category Article
Matti Nuorteva. (1990). Salama puustokuolemien aiheuttajana. Silva Fennica vol. 24 no. 2 article id 5427. https://doi.org/10.14214/sf.a15581
English title: Lightning as a cause of death of tree groups.
English keywords: lightning; forest damage

The writer reports in this discussion article of four stands in Finland that have died due to a bolt of lightning. A death of a group of trees because of lightning has been relatively uncommon for the forest professionals. The trees may not have no lightning marks. The four sites are presented in detail. Characteristic for this type of death of trees is, for instance, that trees have died within a circular area (of usually 30 m of diameter), only conifers have died, trees die from the top down, sometimes marks can be found in trees in the centre of the area, and under the bark may be brown patches or stripes.

  • Nuorteva, ORCID ID:E-mail:
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 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

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, ORCID ID:E-mail:
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

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, ORCID ID:E-mail:
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.

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, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 5171, category Article
Seppo Kellomäki, Pauline Oker-Blom. (1983). Canopy structure and light climate in a young Scots pine stand. Silva Fennica vol. 17 no. 1 article id 5171. https://doi.org/10.14214/sf.a15086

The needle area distribution and crown structure of a young planted Scots pine (Pinus sylvestris L.) stand are described. The crown structure and crown shape showed apparent regularity in crown structure regardless of stand dynamics. Similarly, the shoot structure and individual needle area showed regularity in the number of needles per branch and shoot length unit, and consequent phytoarea density inside the needle cylinder. Also, the shoot area and needle area distributions were found to show a regular distribution of needle biomass throughout the crown, also inside the crown, in the dominant trees. In the suppressed trees the needle biomass was located in the upper crown and on the surface area of the crown. Estimates of the canopy needle area and distributions are given. The results were applied in calculations of the within-stand light regime. The results correlated well with the empirical results.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
article id 5171, category Article
Seppo Kellomäki, Pauline Oker-Blom. (1983). Canopy structure and light climate in a young Scots pine stand. Silva Fennica vol. 17 no. 1 article id 5171. https://doi.org/10.14214/sf.a15086

The needle area distribution and crown structure of a young planted Scots pine (Pinus sylvestris L.) stand are described. The crown structure and crown shape showed apparent regularity in crown structure regardless of stand dynamics. Similarly, the shoot structure and individual needle area showed regularity in the number of needles per branch and shoot length unit, and consequent phytoarea density inside the needle cylinder. Also, the shoot area and needle area distributions were found to show a regular distribution of needle biomass throughout the crown, also inside the crown, in the dominant trees. In the suppressed trees the needle biomass was located in the upper crown and on the surface area of the crown. Estimates of the canopy needle area and distributions are given. The results were applied in calculations of the within-stand light regime. The results correlated well with the empirical results.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
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

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, ORCID ID:E-mail:
  • Oker-Blom, ORCID ID:E-mail:
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

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, ORCID ID:E-mail:
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

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, ORCID ID:E-mail:
  • Kanninen, ORCID ID:E-mail:
article id 5049, category Article
Pirkko Ilonen, Pertti Hari, Markku Kanninen, Seppo Kellomäki. (1979). On distribution of growth in crown system of young Scots pine stands. Silva Fennica vol. 13 no. 4 article id 5049. https://doi.org/10.14214/sf.a14906

Branching and terminal growth of lateral shoots and needle growth of Scots pine (Pinus sylvestris L.) is investigated as a function of the whorl’s position and age and prevailing light climate. Number of buds per whorl was linearly and positively related to the whorl’s position and prevailing light climate. The growing whorl’s number counting from the apex was associated with declining bud number. The terminal growth of lateral shoots increased exponentially within the values 0.6–1.0 of the whorls position. Under these values the terminal growth was negligible. The growing whorl’s number indicated curvlinear decrease in shoot growth respectively, and only negligible growth occurred when the whorl’s age exceeded 10 years. The shoot growth was linearly related to the prevailing light climate but differences between dominating and dominated trees were apparent. The distribution of needle growth in the crown system was similar to that of shoot growth.

The PDF includes a summary in Finnish.

  • Ilonen, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Kanninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 4981, category Article
Seppo Kellomäki, Pertti Hari, Pekka Kauppi, Eero Väisänen. (1977). Production of structural matter by a plant community in successional environment. Silva Fennica vol. 11 no. 4 article id 4981. https://doi.org/10.14214/sf.a14835

The structural matter production of selected plant species of a ground cover community was determined in relation to light available for photosynthesis. The resulting functions were applied in a situation where the light reaching the ground cover was controlled by the dynamics of the tree crown strata, and the occurrence of different plant species at different stages of succession was determined on the basis of their production of structural matter in actual light conditions. The possible strategies involved in adaptation to a successional environment have been discussed.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Kauppi, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 4980, category Article
Eero Väisänen, Pertti Hari, Seppo Kellomäki. (1977). Annual growth level of some plant species as a function of light available for photosynthesis. Silva Fennica vol. 11 no. 4 article id 4980. https://doi.org/10.14214/sf.a14834

A quantitative method for determining the annual growth level of plant species has been presented. In particular, attention was paid to the dependence of the growth level on the amount of light available for photosynthesis. A mathematical model for the dependence of structural matter production on photosynthetic production has been presented for some plant species.

The study is based on the assumption that the total amount of annual net photosynthesis plays a role of primary importance in determining the relationship between photosynthetic production and structural matter production. The basic environmental factors determining the photosynthetic rate are light and temperature, if the water and nutrient supply is adequate. The dependence of photosynthetic rate on light and temperature was determined by monitoring the CO2 uptake rate of natural plant populations between the photosynthetic levels of different plant populations with an infrared gas analyser.

The PDF includes a summary in Finnish.

  • Väisänen, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 4964, category Article
Seppo Kellomäki, Pertti Hari, Eero Väisänen. (1977). Annual production of some forest mosses as a function of light available for photosynthesis. Silva Fennica vol. 11 no. 1 article id 4964. https://doi.org/10.14214/sf.a14815

The aim of the present paper was to study the annual production of Pleurozium schreberi (Brid.) Mitt., Hylocomnium splendens (Hedw.) B.S.G and Dicranum polysetum Sw. as a function of light available for photosynthesis. The productivity of the above moss species is studied using the harvested quadrats method in Norway spruce (Picea abies) stands of the Myrtillus site type representing different stand density classes (basal area from 0 to 34 m2/ha) in Southern Finland.

The annual production of each species in different stands was correlated with the amount of light available for photosynthesis i.e. with the photosynthetic production. Functions for the dependence of productivity on light conditions were produced for each species. The individual functions and their ecological significance is discussed. The adaptation of each species to low light intensity is evident since no meaningful addition to production takes place when the photosynthetic light ratio reaches values greater than 0.3–0.4. In other words, the level of photosynthesis which is 30–40% of that possible in the open, provides sufficient supply of carbohydrates or the basic functions of the moss species studied. Pleurozium schreberi and Dicranum polysetum seem to have greater light requirements than Hylocomnium splendens.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 4953, category Article
Seppo Kellomäki, Pertti Hari. (1976). Rate of photosynthesis of some forest mosses as a function of temperature and light intensity and effect of water content of moss cushion on photosynthetic rate. Silva Fennica vol. 10 no. 4 article id 4953. https://doi.org/10.14214/sf.a14799

The photosynthetic rate of Pleurosium schreberi (Willd.), Hylocomnium splendens (Hedw.) and Dicranum undulatum (Sw.) grown in plastic containers was monitored with infrared gas analyser in open air under natural weather conditions. It proved that the photosynthetic rate of wet moss cushions was satisfactorily predicted by temperature and light intensity. In dry moss cushions this kind of model gave too high an estimate for photosynthetic rate. Water requirements of each moss species were found to be moderate, and water content of moss cushions limited photosynthetic rate only under serious water deficiency.

The PDF includes a summary in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hari, ORCID ID:E-mail:
article id 4937, category Article
Pertti Hari, Mikko Huhtamaa, Paavo Pelkonen, Veli Pohjonen, Raimo Salminen. (1976). A new approach for measuring light inside the canopy in photosynthesis studies. Silva Fennica vol. 10 no. 2 article id 4937. https://doi.org/10.14214/sf.a14782

Light intensity inside the canopy varies considerably both in space and time. A new apparatus was developed which is disturbed as little as possible by the above-mentioned variation. The construction is based on the linear relationships between light intensity (measured using silicon diodes) and photosynthesis. This procedure permits linear operations (summing and integration) to be carried out on the output of the diodes without any loss of accuracy. There are five diodes in each assimilation chamber. A model, in which the independent variables include ligth, measured with the present equipment, and temperature, fits the photosynthetic rates well even inside the canopy.

The PDF includes a summary in Finnish.

  • Hari, ORCID ID:E-mail:
  • Huhtamaa, ORCID ID:E-mail:
  • Pelkonen, ORCID ID:E-mail:
  • Pohjonen, ORCID ID:E-mail:
  • Salminen, ORCID ID:E-mail:
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.

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, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Mäkelä, ORCID ID:E-mail:
  • Ilonen, ORCID ID:E-mail:
  • Kanninen, ORCID ID:E-mail:
  • Korpilahti, ORCID ID:E-mail:
  • Nygren, ORCID ID:E-mail:
article id 7612, category Article
Timo Kurkela. (1969). Antagonism of healthy and diseased Ericaceous plants to snow blight on Scots pine. Acta Forestalia Fennica no. 101 article id 7612. https://doi.org/10.14214/aff.7612

Two experiments were conducted in Punkaharju and Leivonmäki in the Central Finland in 1966-67 where the spread of the snow blight caused by Phacidium infestans Karst. was investigated in rows of excised branches from a ten-year-old stand of Scots pine (Pinus sylvestris L.). Ericaceous plants (Calluna vulgaris (L.) Hull and Vaccinium vitis-idaea L.) infected with snow moulds were used to determine their influence on the spread of snow blight.

The results show that significant inhibition of snow blight in Scots pine can be achieved with foliage of ericaceous evergreens. The mechanism of this inhibition is an object of conjecture. In healthy ericaceous vegetation it might be caused by saprophytic fungi living on surface of plants or by some constituent of the foliage. In the case of dead ericaceous foliage, the cause of inhibition seems to be the antagonism of other snow moulds. The antagonism of certain saprophytic organism is well known.

The observed inhibition suggests that ericaceous vegetation may be helpful for reforestation by offering a natural control of snow blight, when seedlings of Scots pine do not stand above the surrounding vegetation.

The PDF includes a summary in Finnish.

  • Kurkela, ORCID ID:E-mail:

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