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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'xylem'.

Category: Research article

article id 10048, category Research article
Urszula Zajączkowska, Karina Kaczmarczyk, Janusz Liana. (2019). Birch sap exudation: influence of tree position in a forest stand on birch sap production, trunk wood anatomy and radial bending strength. Silva Fennica vol. 53 no. 2 article id 10048.
Highlights: Birch trees along the forest edge exude more xylem sap but less concentrated than the trees from the interior; Radial bending strength of wood in birch trunk is higher in the trees from forest edge; Trees exhibit higher bending strength in western side of the trunk, where the number of vessels and the wood potential conductivity index are smaller.

It is commonly accepted that the period of early-spring xylem sap exudation marks a stage during which a positive pressure builds inside the tree trunks. This state changes when leaves appear, initiating water transport within the trunk. It is unknown, however, how the wood anatomical structure and its mechanical resistance influences the sap. We present the results of research on the relationship between exudation of sap from Betula pendula Roth trees from the interior of a forest stand and from its edge, and the anatomical structure of the trunk wood and its bending strength. During the period between March 21 and April 18, we performed five sets of measurements of sap exudation from trees at the edge of the stand and from the forest interior. The resulting radial wood samples were tested for bending strength using a fractometer. We tested the sap for electrolytic conductivity and sugars content. For the anatomical analysis of the wood, we determined the number of vessels per 1 mm2, average vessel lumen area and potential conductivity index. We found that the trees along the edge of the stand exude more sap, but it is less concentrated than the sap from the trees from the interior. Bending strength perpendicular to wood fibres is higher in the trees from the stand edge and in the western side of the trunk, where the number of vessels per 1 mm2 and conductivity index are smaller. Seemingly, this is the result of western winds, which are dominant in Poland.

  • Zajączkowska, Department of Forest Botany, Faculty of Forestry, Warsaw University of Life Sciences, 159 Nowoursynowska St., 02-776 Warsaw, Poland ORCID ID:E-mail: (email)
  • Kaczmarczyk, Department of Forest Botany, Faculty of Forestry, Warsaw University of Life Sciences, 159 Nowoursynowska St., 02-776 Warsaw, Poland ORCID ID:E-mail:
  • Liana, Department of Forest Botany, Faculty of Forestry, Warsaw University of Life Sciences, 159 Nowoursynowska St., 02-776 Warsaw, Poland ORCID ID:E-mail:
article id 1694, category Research article
Katri Luostarinen, Katja Hakkarainen, Henri Kaksonen. (2017). Wood anatomy of seed and basal bud originated downy birches (Betula pubescens Ehrh.) grown at four different sites. Silva Fennica vol. 51 no. 1 article id 1694.
Highlights: Young xylem of sprouts did not clearly show more mature characteristics than that of seedlings; Marked differences in xylem structure could be observed between growing sites.

In trees, xylem must fulfil three important tasks: conducting water to leaves, storing nutrients and water, and supporting the trunk. The origin of the trunk, i.e., seed or basal bud that forms sprouts, and the growth site may affect xylem anatomy, differences of which can affect successful growth of trees. Both seedlings and sprouts of downy birch (Betula pubescens Ehrh.) from four different growth sites with two different soil media, peat and mineral soil, were studied. The diameter of fibres and vessels and the thickness of the double fibre wall were measured, and the number of vessels, rays and axial parenchyma cells was counted. The fibre wall:lumen ratio, vessel percentage area and vessel size:number ratio were calculated. Xylem from sprouts showed only occasionally more mature characteristics than that of seedlings. The number of rays was similar at all four sites, but differences were observed in all other studied characteristics between sites, particularly if soil type was different. The vessel size and number correlated with the number of axial parenchyma cells in juvenile wood, which emphasises the importance of their connections with storage cells particularly at this stage of growth. Good water conductivity was connected with weaker wood, particularly in maturing wood.

  • Luostarinen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: (email)
  • Hakkarainen, Natural Resources Institute of Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail:
  • Kaksonen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 921, category Research article
Katri Luostarinen. (2012). Tracheid wall thickness and lumen diameter in different axial and radial locations in cultivated Larix sibirica trunks. Silva Fennica vol. 46 no. 5 article id 921.
In Larix trunks the properties of wood differ clearly radially, but the axial differences are smaller as well as being less studied. Wood anatomy is in particular poorly studied, even though all other wood properties derive from cell and tissue structure. The aim of this study was to chart variation in tracheid size (double wall thickness (2CWT), diameter of lumen (RD)) within fast grown cultivated Siberian larch (Larix sibirica Ledeb.) trunks. The differences in 2CWT and RD were clear between earlywood (EW) and latewood (LW), 2CWT increasing clearly less in EW than in LW towards the bark, while RD stayed quite stable in LW but in EW increased markedly towards the bark. The difference in 2CWT between EW and LW increased towards the upper trunk. In conclusion, the radial variation in RD and 2CWT was different between the butt and other studied heights. As the difference in 2CWT between EW and LW was smaller at the butt than the upper portion of the trunk, the wood was the most homogenous at the butt.
  • Luostarinen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: (email)
article id 292, category Research article
Sanna Susiluoto, Frank Berninger. (2007). Interactions between morphological and physiological drought responses in Eucalyptus microtheca. Silva Fennica vol. 41 no. 2 article id 292.
We studied the response of Eucalyptus microtheca to drought in a greenhouse experiment. As a result of the drought the growth of the seedlings decreased and allocation patterns changed so that allocation to the roots increased. However, changes in photosynthesis and stomatal conductance under drought were rather modest. We showed, using chlorophyll fluorescence and measurements of photosynthesis under high CO2 that the biochemical capacity of photosynthesis increased under drought. The results suggest that changes in root/shoot ratio are the primary reactions that initiate a series of compensatory reactions that mitigate the effects of drought in Eucalyptus microtheca.
  • Susiluoto, University of Helsinki, Department of Forest Ecology, PL 27, 00014 University of Helsinki, Finland ORCID ID:E-mail: (email)
  • Berninger, Departement des Sciences biologiques, Université du Québec à Montréal, CP 8888 Succ Centre Ville, Montreal, Canada ORCID ID:E-mail:

Category: Review article

article id 10381, category Review article
Carl F. Salk. (2020). Interpreting common garden studies to understand cueing mechanisms of spring leafing phenology in temperate and boreal tree species. Silva Fennica vol. 54 no. 5 article id 10381.

Trees are particularly susceptible to climate change due to their long lives and slow dispersal. However, trees can adjust the timing of their growing season in response to weather conditions without evolutionary change or long-distance migration. This makes understanding phenological cueing mechanisms a critical task to forecast climate change impacts on forests. Because of slow data accumulation, unconventional and repurposed information is valuable in the study of phenology. Here, I develop and use a framework to interpret what phenological patterns among provenances of a species in a common garden reveal about their leafing cues, and potential climate change responses. Species whose high elevation/latitude provenances leaf first likely have little chilling requirement, or for latitude gradients only, a critical photoperiod cue met relatively early in the season. Species with low latitude/elevation origins leafing first have stronger controls against premature leafing; I argue that these species are likely less phenologically flexible in responding to climate change. Among published studies, the low to high order is predominant among frost-sensitive ring-porous species. Narrow-xylemed species show nearly all possible patterns, sometimes with strong contrasts even within genera for both conifers and angiosperms. Some also show complex patterns, indicating multiple mechanisms at work, and a few are largely undifferentiated across broad latitude gradients, suggesting phenotypic plasticity to a warmer climate. These results provide valuable evidence on which temperate and boreal tree species are most likely to adjust in place to climate change, and provide a framework for interpreting historic or newly-planted common garden studies of phenology.

  • Salk, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE- 230 53 Alnarp, Sweden; Faculty of International Studies, Utsunomiya University, 350 Minemachi, Utsunomiya-shi, Tochigi 321-8505 Japan; Institute for Globally Distributed Open Research and Education (IGDORE) ORCID ID:E-mail: (email)

Category: Article

article id 4938, category Article
Matti Kärkkäinen. (1976). Mäntyrunkojen ydinsäteiden korkeus ja leveys. Silva Fennica vol. 10 no. 2 article id 4938.
English title: Height and width of rays in Scots pine stems.

In this study the width and height of 1,588 uniseriate and 454 fusiform rays were measured from tangential sections of four Scots pine (Pinus sylvestris L.) trunks. The samples represented various height levels and distances from the pith. The average width of the uniseriate rays was 19.7 μm and that of the fusiform rays, 51.9 μm. The average height of the uniseriate rays was 215.7 μm and that of the fusiform rays 406.2 μm. Due to this difference in height, it may be possible to develop an automatic system for distinguishing between uniseriate end fusiform rays on the basis of their height.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
article id 7610, category Article
Matti Leikola. (1969). The influence of environmental factors on the diameter growth of forest trees : Auxanometric study. Acta Forestalia Fennica no. 92 article id 7610.

The influence of various environmental factors on the diameter growth of trees has been studied based on data collected by following daily increment of trees and various environmental factors during the growing season in 1964–1967. The field work was carried out in two experimental stands, a Scots pine (Pinus sylvestris L.) stand and a mixed stands growing birch (Betula sp.), Norway spruce (Picea abies (L.) H. Karst.) and Scots pine, in Southern Finland.

The results show that the temperature sums preceding the beginning of diameter growth were of the same magnitude in the years studied, which indicates dependence in the relationship. Formation of new xylem cells took place in the pine stem ca. every third day when the diameter growth was most active. No summer growth inhibition was detected in diameter growth.

None of the cumulative temperature sums tried determined the time of cessation of diameter growth. In several cases, positive correlation was found between the length of the growing season and the width of the annual ring formed. When studying the relationships between the diameter increment and the environmental factors, it was found that diameter increment was totally masked in the records by the hydrostatic changes in the stem. Relationships between the diameter increment and the environmental factors of the second day preceding growth were found to be poor. In studying the deviations of the recorded daily increments from the regression surface, no clear general trend was seen for pine and spruce, but clear diminishing trend toward the end og the growing season could be seen for birch in 1967.

  • Leikola, ORCID ID:E-mail:

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