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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles by Hannu Lehtonen

Category: Research article

article id 556, category Research article
Timo Kuuluvainen, Juha Mäki, Leena Karjalainen, Hannu Lehtonen. (2002). Tree age distributions in old-growth forest sites in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 556. https://doi.org/10.14214/sf.556
The age and size of trees was sampled and measured on eight sample plots (0.2 ha each) within a Pinus sylvestris -dominated boreal forest landscape in Vienansalo wilderness, Russian Karelia. The fire history of these plots was obtained from a previous dendrochronological study. All the studied sample plots showed a wide and uneven distribution of tree ages, but the shape of the age distributions of trees as well as tree species composition varied substantially. Trees over 250 years of age occurred in every studied plot, despite its small size. This suggests that old Pinus were common and rather evenly distributed in the landscape matrix. The oldest Pinus tree was 525 years of age. The correlations between tree age and size were often weak or even nil. In Pinus the correlation between age and diameter was stronger than that between age and height. In the dominant tree species Pinus and Picea, the largest trees were not the oldest trees. The tree age distributions together with the fire history data indicated that the past fires have not been stand replacing, as many of the older Pinus had survived even several fires. Tree age classes that had regenerated after the last fire were most abundant and dominated by Picea and/or deciduous trees, while the trees established before the last fire were almost exclusively Pinus. The results suggest that periodic occurrence of fire is important for the maintenance of the Pinus-dominated landscape. This is because fire kills most Picea and deciduous trees and at the same time enhances conditions for Pinus regeneration, facilitated by available seed from the continuous presence of old fire-tolerant Pinus trees.
  • Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi (email)
  • Mäki, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Karjalainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Lehtonen, Faculty of Forestry, University of Joensuu, P.O. Box 24, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
article id 616, category Research article
Markus Lindholm, Hannu Lehtonen, Taneli Kolström, Jouko Meriläinen, Matti Eronen, Mauri Timonen. (2000). Climatic signals extracted from ring-width chronologies of Scots pines from the northern, middle and southern parts of the boreal forest belt in Finland. Silva Fennica vol. 34 no. 4 article id 616. https://doi.org/10.14214/sf.616
Climatic signals were extracted from ring-width chronologies of Scots pines (Pinus sylvestris L.) from natural stands of the northern, middle, and southern parts of the boreal forest belt in Finland. The strength of the common growth signals (forcing factors) were quantified as a function of time. This was achieved by mean inter-series correlations, calculated over a moving 30-year window, both within and between the regional chronologies. Strong regional signals and also evidence for common forcings were found, especially between northern and central, central and eastern, as well as central/eastern and southern chronologies. Response function analyses revealed that growing season temperatures govern the growth rates of northern pines, while towards south, pine growth becomes less affected by temperatures, and more affected by e.g. precipitation. During some periods, growing conditions seem to have been favorable in the south, while they have been unfavorable in the north (growth inversions). Going from the north to the south, the variability of radial growth clearly decreases, and the variance of ring-width series becomes smaller. Growth variability in the four regions was compared during the common interval of the chronologies, from 1806 to 1991. The spectral densities of the northern, central, eastern and southern chronologies were also compared as functions of frequency, viz. cycles per year. The variance is much greater and there is more periodic behavior in the north than in the south in high, medium, as well as lower frequencies.
  • Lindholm, Saima Centre for Environmental Sciences, University of Joensuu, Linnankatu 11, FIN-57130 Savonlinna, Finland ORCID ID:E-mail:
  • Lehtonen, Finnish Forest Research Institute, Joensuu Research Station, Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Kolström, Finnish Forest Research Institute, Joensuu Research Station, Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Meriläinen, Saima Centre for Environmental Sciences, University of Joensuu, Linnankatu 11, FIN-57130 Savonlinna, Finland ORCID ID:E-mail:
  • Eronen, Department of Geology, Division of Geology and Palaeontology, Box 11, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Timonen, Finnish Forest Research Institute, Rovaniemi Research Station, Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail:

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