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

Category: Research article

article id 10001, category Research article
Karoliina Hämäläinen, Teemu Tahvanainen, Kaisa Junninen. (2018). Characteristics of boreal and hemiboreal herb-rich forests as habitats for polypore fungi. Silva Fennica vol. 52 no. 5 article id 10001. https://doi.org/10.14214/sf.10001
Highlights: Polypore species richness and diversity were affected positively by dead-wood diversity, and negatively by increasing latitude; Red-listed species responded only to the abundance of large-diameter dead wood; Main factor determining composition of polypore assemblages was host-tree species; High proportion of deciduous dead-wood in herb-rich forests provides complementary effect on polypore assemblages in boreal forest landscapes.

Herb-rich forests are often considered biodiversity hotspots in the boreal zone but their fungal assemblages, particularly those of wood-decaying fungi, remain poorly known. We studied herb-rich forests as habitats for polypores, a distinct group of wood-decaying fungi, and assessed the importance of tree- and stand-scale variables for polypore species richness, abundance, and diversity, including red-listed species. The data include 71 herb-rich forest stands in Finland and 4797 dead wood items, on which we made 2832 observations of 101 polypore species. Dead-wood diversity was the most important variable explaining polypore species richness and diversity, whereas increasing latitude had a negative effect. Red-listed species showed a positive response to the abundance of large-diameter dead wood, which, especially birch, supported also high general abundance of polypores. The composition of polypore assemblages reflected their host-tree species. The red-listed species did not show explicit patterns in the ordination space. Compared to old-growth spruce forests, herb-rich forests seem to host lower polypore species richness and less red-listed species. However, because of high proportion of deciduous trees in the dead wood profile, herb-rich forests have a clear complementary effect on polypore assemblages in boreal forest landscapes.

  • Hämäläinen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: karoham@uef.fi (email)
  • Tahvanainen, Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: teemu.tahvanainen@uef.fi
  • Junninen, Metsähallitus Parks & Wildlife Finland, c/o UEF/Borealis, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: kaisa.junninen@metsa.fi
article id 1740, category Research article
Ram P. Sharma, Zdeněk Vacek, Stanislav Vacek. (2017). Modelling tree crown-to-bole diameter ratio for Norway spruce and European beech. Silva Fennica vol. 51 no. 5 article id 1740. https://doi.org/10.14214/sf.1740
Highlights: Modelled crown-to-bole diameter ratio (CDBDR) using tree and stand-level predictors, and sample plot random effects; Spatially explicit mixed-effects model described the largest part of CDBDR variation with no significant trend in the residuals; The CDBDR increased with increasing stand development stage and site quality, but decreased with decreasing proportion of the species of interest, and increasing competition.

Crown dimensions are correlated to growth of other parts of a tree and often used as predictors in growth models. The crown-to-bole diameter ratio (CDBDR), which is a ratio of maximum crown width to diameter at breast height (DBH), was modelled using data from permanent sample plots located on Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) stands in different parts of the Czech Republic. Among various tree and stand-level measures evaluated, DBH, height to crown base (HCB), dominant height (HDOM), basal area of trees larger in diameter than a subject tree (BAL), basal area proportion of the species of interest (BAPOR), and Hegyi’s competition index (CI) were found to be significant predictors in the CDBDR model. Random effects were included using the mixed-effects modelling to describe sample plot-level variation. For each species, the mixed-effects model described a larger part of the variation of the CDBDR than nonlinear ordinary least squares model with no trend in the residuals. The spatially explicit mixed-effects model showed more attractive fit statistics [conditional R2 ≈ 0.73 (spruce), 0.78 (beech)] than its spatially inexplicit counterpart [conditional R2 ≈ 0.71 (spruce), 0.76 (beech)]. The model showed that CDBDR increased with increasing HDOM – a measure that combines the stand development stage and site quality – but decreased with increasing HCB and competition (increasing BAL and CI), and decreasing proportions of the species of interest (increasing BAPOR). For both species, the spatially explicit mixed-effects model should be a preferred choice for a precise prediction of the CDBDR. The CDBDR model will have various management implications such as determination of spacing, stand basal area, stocking, and planning of appropriate species mixture.

  • Sharma, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: sharmar@fld.czu.cz (email)
  • Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: vacekz@fld.czu.cz
  • Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic ORCID ID:E-mail: vacekstanislav@fld.czu.cz
article id 1341, category Research article
Přemysl Humplík, Petr Čermák, Tomáš Žid. (2016). Electrical impedance tomography for decay diagnostics of Norway spruce (Picea abies): possibilities and opportunities. Silva Fennica vol. 50 no. 1 article id 1341. https://doi.org/10.14214/sf.1341
Highlights: Statistical parameters of EIT datasets with values of electrical resistance of heartwood are possible to employ in refining heartwood rot diagnostics; Sapwood proportion is decreasing as the proportion of decay on the radial cut expands; Using EIT datasets and sapwood proportion, trees with rot can be split into two groups as per proportion of decay: [< 35%] and [> 35%].

The paper aimed at testing the potential of refining tree rot diagnostics carried out by means of electrical impedance tomography (EIT). Examined was the use of EIT datasets with electrical resistance values and sapwood proportion determined on the basis of tomograms. Making use of datasets with resistance values in EIT rot diagnostics is not a default method, although datasets stay unaffected by a fixed colour scale and subsequent subjective evaluation unlike tomograms. Tomography measurement was carried out for 27 individuals of Norway spruce (Picea abies [L.] Karst.) in two stands north-east of Brno, Czech Republic. Once felled down, radial cut-outs were sampled at the measurement site and used for localising rot and determining the extent of the area of decay. The results were subsequently compared with tomograms. EIT datasets containing values of electrical resistance found by measuring were statistically processed and compared with the extent of rot area identified within the cuts. Sapwood proportion values were also detected using the tomograms. The baseline assumption that sapwood proportion decreases as the rot area in the radial cut expands was confirmed. In trees with rot percentage to 35% approximately, sapwood proportion was exceeding 30% except one tree. In trees with rot percentage exceeding 35%, sapwood proportion was below 30%. On the basis of interpreted datasets, the trees can be split into three characteristic groups that correspond to the occurrence, extent and nature of the rot.

  • Humplík, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 1665/3, 613 00 Brno, Czech Republic ORCID ID:E-mail: premysl.humplik@mendelu.cz (email)
  • Čermák, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 1665/3, 613 00 Brno, Czech Republic ORCID ID:E-mail: petr.cermak@mendelu.cz
  • Žid, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 1665/3, 613 00 Brno, Czech Republic ORCID ID:E-mail: tomas.zid@mendelu.cz
article id 980, category Research article
Atte Komonen, Panu Halme, Mari Jäntti, Tuuli Koskela, Janne S. Kotiaho, Tero Toivanen. (2014). Created substrates do not fully mimic natural substrates in restoration: the occurrence of polypores on spruce logs. Silva Fennica vol. 48 no. 1 article id 980. https://doi.org/10.14214/sf.980
Highlights: Polypore communities were more homogeneous among created than among natural logs; The old-growth forest indicator Phellinus ferrugineofuscus occurred frequently on natural logs, but occupied only a few created logs; Results show that created logs do not fully mimic natural logs.
Many protected areas have been under intensive forest management prior to protection and thus lack natural ecosystem structures and dynamics. Dead wood is a key structure in forests harboring hundreds of threatened species. We investigated the ecological success of dead wood creation as a boreal forest restoration measure. We analysed whether the polypore communities of chain-saw felled and girdled (subsequently fallen) Norway spruce (Picea abies (L.) H. Karst.) logs differ from naturally formed spruce logs of similar decay stage and size. The study was conducted in Leivonmäki National Park in central Finland 8 years after the restoration measures. The average number of polypore species was highest on the chain-saw felled logs and most of the common polypore species were most frequent on this substrate. However, among the natural logs, number of species increased more steeply with increasing number of logs, suggesting greater variation in community composition on this substrate. The old-growth forest indicator Phellinus ferrugineofuscus occurred frequently on natural logs, occupied a few girdled logs but was absent from chain-saw felled logs. Our results show that from the polypore perspective created logs do not fully mimic natural logs, suggesting that creating substrates for species may pose a challenge for restoration.
  • Komonen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: atte.komonen@jyu.fi (email)
  • Halme, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: panu.halme@jyu.fi
  • Jäntti, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: mari.j.jantti@student.jyu.fi
  • Koskela, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: tuuli.e.koskela@student.jyu.fi
  • Kotiaho, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: janne.kotiaho@jyu.fi
  • Toivanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland; Current: Birdlife Finland, Annankatu 29 A 16, FI-00100 Helsinki, Finland ORCID ID:E-mail: tero.toivanen@birdlife.fi
article id 954, category Research article
Anna-Maria Eriksson, Jörgen Olsson, Bengt Gunnar Jonsson, Sara Toivanen, Mattias Edman. (2013). Effects of restoration fire on dead wood heterogeneity and availability in three Pinus sylvestris forests in Sweden. Silva Fennica vol. 47 no. 2 article id 954. https://doi.org/10.14214/sf.954
Restoration fires are increasingly used as a conservation tool in Sweden to recreate forests with characteristics of previous forests that were periodically disturbed by fires and promote fire-dependent species. Restoration fires can result in large inputs of fresh dead wood, but there are risks of losing some of the existing, pre-fire dead wood. To assess these counteracting effects we studied the heterogeneity and availability of dead wood before and after three restoration fires in boreal Scots pine forests. Specifically, we studied volumes of stumps, high stumps, snags and logs. The fires decreased the total volume of pre-fire dead wood (23-41%) and consumed logs in late decay stages (26-54%) to a higher extent than logs in earlier stages. The input of new fresh dead wood after the fires exceeded losses of pre-fire dead wood and resulted in a net increase of dead wood in all three sites. The added dead wood consisted of fresh snags killed by the fires. Fire also affected log characteristics: reducing their vegetation coverage (60-98%), decreasing their ground contact (4-50%) and increasing their surface area of charred wood (>50%). Such changes have important consequences for the micro environmental conditions inside logs, but have been rarely studied in relation to restoration fires. Our results show that restoration fire causes changes in dead wood availability and characteristics of logs. The results imply that ideally stands with low abundance of rare and heavily decayed wood substrates should be burned to optimize dead wood values. Alternatively, management practices should include protection of these substrates during restoration fires.
  • Eriksson, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden ORCID ID:E-mail: anna-maria.eriksson@miun.se (email)
  • Olsson, Department of Ecology and Environmental Science, Umeå University, SE-901 87, Umeå, Sweden ORCID ID:E-mail: jorgen.m.olsson@slu.se
  • Jonsson, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden ORCID ID:E-mail: bengt-gunnar.jonsson@miun.se
  • Toivanen, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden ORCID ID:E-mail: sara.toivanen@lansstyrelsen.se
  • Edman, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden ORCID ID:E-mail: mattias.edman@miun.se
article id 112, category Research article
Mike R. Saunders, Shawn Fraver, Robert G. Wagner. (2011). Nutrient concentration of down woody debris in mixedwood forests in central Maine, USA. Silva Fennica vol. 45 no. 2 article id 112. https://doi.org/10.14214/sf.112
Both nutrient concentrations and pre- and post-harvest pool sizes were determined across down woody debris decay classes of several hardwood and softwood species in a long-term, natural disturbance based, silvicultural experiment in central Maine. Concentrations of N, P, Ca, Mg, Cu, Fe, and Zn generally increased 2- to 5-fold with increasing decay class. Concentrations of Mn, Al and B did not differ among decay classes, while K decreased by 20–44% from decay class 1 to class 4. C:N-ratios declined with increasing decay class, while N:P-ratios increased from decay class 1 to 2 and then plateaued with further decay. Within decay classes, softwoods generally had lower nutrient concentrations and higher C:N-ratios than hardwoods; N:P-ratios did not differ between hardwoods and softwoods. Although gap harvesting increased the size of the overall down woody debris nutrient pools, mostly through a large pulse of decay class 1 material, harvesting generally reduced the nutrients held in advanced decay classes. Pre-harvest down woody debris pools for N, P, K and Ca were 11.0, 0.6, 2.1 and 21.1 kg ha–1, respectively, while postharvest were 20.0, 1.3, 6.2 and 46.2 kg ha–1, respectively. While the gap-based silvicultural systems sampled in this study doubled the size of the pre-harvest, downed woody debris nutrient pools, the post-harvest pools were estimated to be only 3.2–9.1% of aboveground nutrients.
  • Saunders, Department of Forestry and Natural Resources, Purdue University, 715 State Street, West Lafayette, IN, USA ORCID ID:E-mail: msaunder@purdue.edu (email)
  • Fraver, USFS Northern Research Station, Grand Rapids, MN, USA ORCID ID:E-mail:
  • Wagner, School of Forest Resources, University of Maine, Orono, ME, USA ORCID ID:E-mail:
article id 179, category Research article
Henna Vartiamäki, Jarkko Hantula, Antti Uotila. (2009). Susceptibility of silver birch pruning wounds to infection by white-rot fungus (Chondrostereum purpureum), a potential bioherbicide. Silva Fennica vol. 43 no. 4 article id 179. https://doi.org/10.14214/sf.179
We artificially inoculated pruning wounds of silver birch (Betula pendula Roth) to study seasonal variation in their vulnerability to infection by the fungal decomposer Chondrostereum purpureum (Pers. ex Fr.) Pouzar. This information is critical to the assessment of incidental infection risks in areas where C. purpureum may be used as a bioherbicide. On seven monthly occasions between April and October 2005, 30 birch trees were pruned to yield a total of 210 experimental trees. On each occasion, 10 trees were inoculated immediately with C. purpureum mycelium, 10 were inoculated with blank inoculum and 10 were only pruned. In the summer of 2007, a survey of 129 experimental trees showed that pruning wounds were most susceptible to infection during May. Treatment with C. purpureum at other times during the growing season also increased the extent of discoloration or decay but the effect was considerably less.
  • Vartiamäki, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: henna.vartiamaki@metla.fi (email)
  • Hantula, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Uotila, University of Helsinki, Hyytiälä Forestry Field Station, Hyytiäläntie 124, FI-35500 Korkeakoski, Finland ORCID ID:E-mail:
article id 246, category Research article
Maria Jonsson. (2008). Live-storage of Picea abies for two summers after storm felling in Sweden. Silva Fennica vol. 42 no. 3 article id 246. https://doi.org/10.14214/sf.246
After recent severe storm fellings in Sweden, as harvest, transport, and storage capacities were insufficient, interest in live-storage (leaving windthrown trees in the stand) increased. This study follows windthrown Norway spruce (Picea abies (L.) Karst.) trees during 20 months, i.e. two summers, of live-storage in southern Sweden. Moisture content, blue stain, and storage decay were compared in trees from a site with all trees windthrown and a site with scattered windthrows. After the first summer of live-storage, the quality losses were small. After 20 months, the trees had dried significantly and had numerous infestations of blue stain and storage decay. Trees from the site with scattered windthrows were of better quality compared to trees from the site with all trees windthrown. Live-storage is a suitable method for one year of storage, but the second year losses in wood quality are considerable.
  • Jonsson, Swedish University of Agricultural Sciences, Dept. of Forest Products, Uppsala, Sweden ORCID ID:E-mail: maria.jonsson@sprod.slu.se (email)
article id 259, category Research article
Jani Laturi, Jarmo Mikkola, Jussi Uusivuori. (2008). Carbon reservoirs in wood products-in-use in Finland: current sinks and scenarios until 2050. Silva Fennica vol. 42 no. 2 article id 259. https://doi.org/10.14214/sf.259
This study addresses the question of how much carbon will be sequestered in wood products during the coming decades in Finland. Using sawnwood and other wood material consumption data since the 1950s and inventory data of carbon reservoirs of wood products in the Finnish construction and civil engineering sector, we first derive estimates for the carbon reservoirs in wood products-in-use in that sector. We then extend the estimate to include all wood products-in-use. We find that the carbon pool of wood products in the Finnish construction and civil engineering sector grew by about 12% since an inventory for 2000, and that the overall estimate for carbon reservoirs of Finnish wood products in 2004 was 26.6 million tons of carbon. In building the scenarios until 2050, econometric time series models accounting for the relationship between wood material consumption and the development of GDP were used. The results indicate that the range of carbon reservoirs of wood products in Finland will be 39.6–64.2 million tons of carbon in the year 2050. The impacts of different forms of the decay function on the time-path of a carbon sink and its value in wood products were also studied. When a logistic decay pattern is used, the discounted value of the predicted carbon sink of wood products in Finland is between EUR850 and EUR1380 million – at the price level of EUR15/CO2 ton – as opposed to 440–900 million euros, if a geometric decay pattern is used.
  • Laturi, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: jani.laturi@metla.fi (email)
  • Mikkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Uusivuori, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 479, category Research article
Ken Olaf Storaunet, Jørund Rolstad, Ivar Gjerde, Vegard S. Gundersen. (2005). Historical logging, productivity, and structural characteristics of boreal coniferous forests in Norway. Silva Fennica vol. 39 no. 3 article id 479. https://doi.org/10.14214/sf.479
Conservation of forest biodiversity has brought about an interest in evaluating the naturalness of forests, and to locate and protect semi-natural and old-growth forests in the Fennoscandian countries. However, it is not always clear how natural these forests really are, and how the past management history has affected their present structural composition. We studied the relationships between cut stumps from historical logging activity (50–100 years ago) and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway. We also studied how forest productivity influenced these relationships. In plots with negligible logging impact we found the amount of living trees, dead wood, and size of the oldest trees mainly to increase with increasing productivity, whereas the age of the oldest trees decreased. The amount of deciduous trees was generally low irrespective of productivity. The intensity of logging did not consistently influence most of these forest structural variables, neither at low- nor at high-productive sites. The only consistent relationship in all study areas was a decreasing amount of dead wood with increasing logging intensity at high-productive sites. Also, the decay class distribution of dead wood was more right-skewed (indicating on-going accumulation of dead wood) the more logging had occurred at high-productive sites. Except from the effects on dead wood, previous logging does not show up as a major determinant of other stand structures of today.
  • Storaunet, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway ORCID ID:E-mail: ken.storaunet@skogforsk.no (email)
  • Rolstad, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway ORCID ID:E-mail:
  • Gjerde, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway ORCID ID:E-mail:
  • Gundersen, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway ORCID ID:E-mail:
article id 672, category Research article
Rimvydas Vasiliauskas, Jan Stenlid. (1998). Spread of Stereum sanguinolentum vegetative compatibility groups within a stand and within stems of Picea abies. Silva Fennica vol. 32 no. 4 article id 672. https://doi.org/10.14214/sf.672
A total of 57 naturally established Stereum sanguinolentum isolates was obtained from artificially wounded Picea abies stems in a forest area of 2 ha in Lithuania. Somatic incompatibility tests revealed 27 vegetative compatibility groups (VCGs) that contained 1–10 isolates. There was no spatial clustering of S. sanguinolentum VCGs within the forest area. The extent of S. sanguinolentum decay was analysed in 48 P. abies stems, 9–26 cm in diameter at breast height. Within 7 years of wounding, the length of S. sanguinolentum decay column in stems was 107–415 cm (291.5 ± 77.3 cm on average), lateral spread of the fungus at the butt was 38–307 cm2 (142.3 ± 66.8 cm2) and decayed proportion of the stem cross-section at the wound site (the butt) was 3–84% (36.8 ± 19.7%). In average, S. sanguinolentum VCG that infected 10 trees exhibited more slow growth inside the stem than VCGs that infected only one tree, and vertical growth varied to a greater extent within this VCG than among different VCGs. Correlation between stem diameter and vertical spread of S. sanguinolentum was not significant (r = –0.103). Despite uniformity of debarked area on all stems 7 years ago (300 cm2), open wound sizes on individual trees at the time of study were between 97–355 cm2 (215.1 ± 59.2 cm2) indicating large differences in wound healing capacity.
  • Vasiliauskas, Department of Plant Protection, Lithuanian University of Agriculture, LT-4324 Kaunas, Lithuania ORCID ID:E-mail:
  • Stenlid, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, S-750 07 Uppsala, Sweden ORCID ID:E-mail:

Category: Research note

article id 1320, category Research note
Abbot Okotie Oghenekaro, Geoffrey Daniel, Fred O Asiegbu. (2015). The saprotrophic wood-degrading abilities of Rigidoporus microporus. Silva Fennica vol. 49 no. 4 article id 1320. https://doi.org/10.14214/sf.1320
Highlights: Rigidoporus microporus isolates displayed varying saprotrophic capabilities on wood blocks of Rubber tree (Hevea brasiliensis); Percentage mass loss of (Hevea brasiliensis) wood blocks caused by the pathogenic Rigidoporus microporus was significantly higher than that observed with the endophytic isolate; The endophytic isolate has very poor saprotrophic ability on Hevea brasiliensis wood blocks.

Saprotrophic wood-decaying abilities of Rigidoporus microporus (Polyporales, Basidiomycota) syn. Rigidoporus lignosus and the structural alterations induced in wood blocks of Hevea brasiliensis Muell. Arg were studied. Mass loss of wood blocks was analyzed after 3 and 6 months respectively and the patterns of decay by pathogenic and endophytic isolates of this fungus were investigated using light microscopy. Effects of temperature on growth of the isolates on malt extract agar were also investigated. The R. microporus isolated from a non-H. brasiliensis host caused the highest percentage mass loss (27.2% after 6 months), followed by isolates ED310 (21.1%) and M13 (15.7%), both collected from diseased H. brasiliensis plantations. The isolate initially identified as an endophyte showed very low saprotrophic wood decay capability (4.3% after 6 months). The optimal temperature for growth of the isolates was 30 °C; except for the endophytic isolate which showed highest growth at 25 °C. Wood samples degraded by the R. microporus isolates showed simultaneous attack of wood cell walls, typical of white rot fungi. Results of the study indicate variability in the wood degrading abilities of the isolates and the potential differences in their physiology are discussed. Our findings further support the need for a taxonomical revision of the Rigidoporus genus.

  • Oghenekaro, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: abbot.oghenekaro@helsinki.fi (email)
  • Daniel, Department of Forest Products/Wood Science, Swedish University of Agricultural Sciences, P.O. Box 7008, SE-75007 Uppsala, Sweden ORCID ID:E-mail: geoffrey.daniel@slu.se
  • Asiegbu, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: fred.asiegbu@helsinki.fi
article id 91, category Research note
Raisa Mäkipää, Tapio Linkosalo. (2011). A non-destructive field method for measuring wood density of decaying logs. Silva Fennica vol. 45 no. 5 article id 91. https://doi.org/10.14214/sf.91
Decaying dead wood density measurements are a useful indicator for multiple purposes, such as for estimating the amount of carbon in dead wood and making predictions of potential diversity of dead wood inhabiting fungi and insects. Currently, qualitative decay phases are used as wood density estimates in many applications, since measuring the density is laborious. A quantitative measure of density would, however, be preferred over the qualitative one. Penetrometers, which are commonly used for measuring the density of standing trees, might also be applicable to dead wood density measurements. We tested the device for making quick, quantitative measurements of decaying logs. The penetrometer measures the depth into which a pre-loaded spring forces a pin in the wood. We tested pins of 5 and 10 mm diameter together with an original 2.5 mm pin and compared the results with gravimetric density measurements of the sample logs. Our results suggest that the standard pin works for less decayed wood, but for more decomposed wood, the thicker 5 mm pin gave more reliable estimates when the penetration measures were converted to densities with a linear regression function (R2 = 0.62, F = 82.9, p = 0.000). The range of wood densities successfully measured with the 5 mm pin was from 180 to 510 kg m–3. With the 10 mm pin, the measuring resolution of denser wood was compromised, while the improvement at the other end of density scale was not large. As a conclusion, the penetrometer seems to be a promising tool for quick density testing of decaying logs in field, but it needs to be modified to use a thicker measuring pin than the standard 2.5 mm pin.
  • Mäkipää, The Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail: raisa.makipaa@metla.fi (email)
  • Linkosalo, The Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail:

Category: Article

article id 7400, category Article
P. S. Tikka. (1949). Perä-Pohjolan koivikoiden laadusta. Acta Forestalia Fennica vol. 57 no. 4 article id 7400. https://doi.org/10.14214/aff.7400
English title: Quality of birch (Betula sp.) stands in the northernmost Finland.

The quality of birch (Betula sp.) stands in Perä-Pohjola in Northern Finland is low due to the harsh environment, unsuitable sites for the species and unsatisfactory silvicultural state. A total of 236 sample trees were felled and measured in 8 sample plots. The trees were over 80 years old.

Only third of the stand volume of birch in the stands had adequate quality for merchantable timber. This is due to birch growing often in sites unsuitable for the species, the low density of the stands, the small average size of stems, and the low amount of large sized trees. These problems may contribute to the fact that birch seem to be susceptible to decay. The trees have often grown from sprouts, which leads often to poor stem form and decay. The volume and quality of both pure and mixed birch stands was sufficient only in the most fertile sites. Also, decay was more common in poor sites.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 7389, category Article
P. S. Tikka. (1947). Perä-Pohjolan kuusikoiden laadusta. Acta Forestalia Fennica vol. 55 no. 1 article id 7389. https://doi.org/10.14214/aff.7389
English title: Quality of Norway spruce stands in Peräpohjola in Northern Finland.

The different kinds of injuries in Norway spruce (Picea abies (L.) Karst.) stands was studied in 52 sample plots in Peräpohjola in the northernmost Finland. The age classes of the stands varied from 100 years to over 220 years. Most of the stands were unevenaged, as is usual in the area.

In the younger age classes (121-160 years) majority of the trees were of normal quality or had smaller injuries in all forest types. In age classes over 160 years the trees of merchantable quality decreased markedly in all forest types. The quality of the trees decreases with the age especially because of butt rot, braking of trees and crooks, forks and heart and top decay caused by the injuries. To ensure future quality it would be important that the stand is healthy from the beginning. When old spruce stands of the area are in large extent diseased by the root rot, it is questionable if they can be regenerated using natural regeneration. The spruce stands of the area are also relatively branchy. This could be prevented by growing the young stands dense. Changing the dominant tree species to Scots pine (Pinus sylvestris L.) in the dry upland forest sites could be a way to improve the quality of the forests in the area.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 7356, category Article
Peitsa Mikola. (1942). Koivun vesomisesta ja sen metsänhoidollisesta merkityksestä. Acta Forestalia Fennica vol. 50 no. 3 article id 7356. https://doi.org/10.14214/aff.7356
English title: Silvicultural usefulness of sprouting of birch.

Birches’ (Betula sp.) ability to grow sprouts is low. The stump grows root collar and stump shoots, but the stump shoots are not proper stump shoots that will grow from the space between wood and bark. The buds are situated very low in the base, even under the ground. In this study, no actual root shoots could be found. Also the bushy alpine birches seem to be formed from stump and root collar shoots.

In Southern Finland silver birch (Betula pendula Roth) is more common than downy birch (Betula pubescens Ehrh.) in dry upland forest sites, while downy birch is common in fresh mineral soil forests and peatlands. In Northern Finland downy birch is the dominant birch species. Of the two species downy birch has markedly better capacity to form stump and root collar shoots both in Northern and Southern Finland. In general, birches grow sprouts much more strongly in Northern Finland.

Growth of the shoots is fastest during the first year after the felling of the parent tree and slows down gradually. The stump shoots may get separated from the stump when the stump decays, and the decay may also spread to the shoots. It is common that the shoots have no own roots, and die along with the stump. The shoots may have own root system or use roots of the parent tree that have stayed alive, in the latter case decay spreads almost always from the stump to the shoot. Whether the tree was felled with axe or saw had no effect on sprouting, probably because the sprouting buds are situated in the base of the tree. The larger stumps had usually fewer sprouts than smaller stumps. The fertility of the site seemed to have little effect on sprouting, but more moist sites formed more sprouts.

Forest regeneration using sprouts may be possible in peatlands for firewood production. on mineral soil sites birch does not suit for coppicing. The proportion of trees originating from sprouts decreases strongly by the time. Consequently, in Southern Finland sprouts have little effect on regeneration of birch. In Northern Finland sprouting is the most important way of regeneration.

The PDF includes a summary in German.

  • Mikola, ORCID ID:E-mail:
article id 7340, category Article
P. S. Tikka. (1938). Puiden vikanaisuuksien vaikutuksesta hakkuutulokseen Perä-Pohjolan havumetsissä. Acta Forestalia Fennica vol. 46 no. 5 article id 7340. https://doi.org/10.14214/aff.7340
English title: The effect of injuries of the stems to amount of merchantable timber in the northernmost Finland.

The effect of different kinds of injuries in the amount of merchantable timber was studied in 57 sample plots in the northernmost Finland. Without any injuries the yield of timber would have been 72.3% in Scots pine (Pinus sylverstris L.) and 89.9% in Norway spruce (Picea abies (L.) H. Karst.). Butting, and removal of parts of the stems due to Injuries decreased the volume by 10.4% in pine and 13.5% in spruce. The main cause for butting of pine was fire wounds, and butt rot in spruce. Also pine blister rust (Peridermium pini and Cronartium flaccidum) causes injuries in Scots pine. The better the forest site type, the smaller is the timber discarded due to injuries. In pine 54% and in spruce 53% of the trees and were healthy. The forests in the northernmost Finland are over-mature which increase the occurrence of fire wounds and decay. Thus, forest fire control and the felling or thinning of over-mature stands will improve the quality of the timber in the long run.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 7314, category Article
P. S. Tikka. (1935). Puiden vikanaisuuksista Pohjois-Suomen metsissä: tilastollis-metsäpatologinen tutkimus. Acta Forestalia Fennica vol. 41 no. 1 article id 7314. https://doi.org/10.14214/aff.7314
English title: Injuries in different tree species in Northern Finland: A statistical-forest pathological study.

The aim of the study was to find out what are the causes of damage in different parts of the trees and the frequency of different kinds of injuries. Sample plots were studied in over 80-year old forests in mineral soil sites and peatlands. All the trees over 1.5 m high were felled in the sample plots and the stem injuries were studied. The structure of the stand and the crown classes were recorded. The proportion of undamaged trees was largest in in dominant and codominant trees and increased towards the better forest site types. The typical injuries are listed for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L). H. Karst.) and Betula sp. stands. The injuries were divided in inner and outer form defects and injuries, and defined in more detail by the part of the stem and tree species. Defects caused by decay were analyzed separately.

Healing over of injuries was faster in the better sites. Form defects and other injuries were more common in birch stands than in Scots pine and Norway spruce stands. Decay was most common in birch stands. The pine stands were the healthiest, followed by spruce stands. Fire wound were most usual in pine, butt rot for spruce, and crooks and general decay for birch.

The PDF includes a summary in German.

  • Tikka, ORCID ID:E-mail:
article id 5566, category Article
Reijo Penttilä, Heikki Kotiranta. (1996). Short-term effects of prescribed burning on wood-rotting fungi. Silva Fennica vol. 30 no. 4 article id 5566. https://doi.org/10.14214/sf.a8501

The prefire fungal flora (polypores and corticoid fungi) of 284 dead trees, mainly fallen trunks of Norway spruce (Picea abies (L.) H. Karst.), was studied in 1991 in an old, spruce-dominated mesic forest in Southern Finland. Species diversity of the prefire fungal flora was very high, including a high proportion of locally rare species and four threatened polypore species in Finland.

In 1992 part of the study area (7.3 ha) was clear-cut and a 1.7 ha forest stand in the centre of study area was left standing with a tree volume of 150 m3/ha, and later on (June 1st) in the same year the whole area was burned. Burning was very efficient and all trees in the forest stand were dead one year after the fire. Also, the ground layer burned almost completely.

In 1993 the fungal flora of the 284 sample trees was studied again. Most of the trees had burned strongly and the fungal species diversity and the evenness in community structure had decreased considerably as compared with the prefire community. Species turnover was also great, especially in corticoid fungi. Greatest losses in the species numbers occurred in moderately and strongly decayed trees, in coniferous trees and in very strongly burned trees. Fungal flora of non-decayed and slightly decayed trees, deciduous trees and slightly burned trees seemed to have survived the fire quite well, and in these groups the species numbers had increased slightly as compared with the prefire community.

Fungal species suffering from fire (anthracophobe species) were mainly growing in moderately and strongly decayed trees before the fire, whereas species favoured by fire (anthracophile species) were growing in less decayed trees. No fruitbodies of threatened polypores or other "old-forest species" of polypores were found again after fire. Some very common and effective wood-rotting fungi (e.g. Fomitopsis pinicola, Fomes fomentarius, Antrodia serialis) survived the fire quite well (anthracoxene species). Species favoured by fire were mainly ruderal species which can utilize new, competition-free resources created by fire, and species that have their optima in dry and open places also outside forest-fire areas. Some rarities, e.g. Phanerochaete raduloides and Physisporinus rivulosus, were favoured by fire.

  • Penttilä, ORCID ID:E-mail:
  • Kotiranta, ORCID ID:E-mail:
article id 5310, category Article
Petri Kärenlampi. (1987). Puun lahonkestävyys ja kosteusdynamiikka. Silva Fennica vol. 21 no. 2 article id 5310. https://doi.org/10.14214/sf.a15467
English title: The decay resistance and moisture dynamics of wood.

In laboratory studies the heartwood content seems to be the only natural property of a wood of different tree species influencing the decay resistance. Moistening and drying by diffusion happen quite slowly. Scots pine (Pinus sylvestris L.) sapwood takes moisture by capillary action quicker than pine heartwood and Norway spruce (Picea abies (L.) H. Karst.) wood. Swelling and shrinkage are also greatest in pine sapwood. Impregnation of pine sapwood can give it better hydrophobic and dimensional stability than that of pine heartwood.

The PDF includes an abstract in English.

  • Kärenlampi, ORCID ID:E-mail:
article id 5216, category Article
Anna-Maija Hallaksela. (1984). Causal agents of butt-rot in Norway spruce in southern Finland. Silva Fennica vol. 18 no. 3 article id 5216. https://doi.org/10.14214/sf.a15395

A total of 146 Norway spruce-dominated clear-cutting areas and 140 of the sample plots included in the 7th National Forest Inventory in Finland were examined during 1974–78. The micro-organisms causing decay in Norway spruce (Picea abies (L.) H. Karst.) sample trees were identified. The most common causal agent of butt-rot was Heterbasidion annosum (Fr.) Bref. Other fungi causing decay in the spruce trees were Armillaria mellea (Vahl.) Quél, Stereum sanguinolentum (Alb. & Schw. ex Fr.), Resinicum bicolor (Alb. & Schw. ex Fr.) Parm. and Climacocystis borealis (Fr.) Kotl. & Pouz. Species of Ascocoryne were very often present in the decay. The decay caused by H. annosum was considerably more extensive than cases of decay where the fungus was not present.

The PDF includes a summary in Finnish.

  • Hallaksela, ORCID ID:E-mail:
article id 5051, category Article
Aili Tuimala. (1979). Kuusen lahon aiheuttamista puutavaralajisiirtymistä ja kantohintamenetyksistä. Silva Fennica vol. 13 no. 4 article id 5051. https://doi.org/10.14214/sf.a14908
English title: Changes in timber assortments and loss in stumpage prices caused by decay in growing Norway spruce timber.

Material for this study was collected from 26 stands marked for clear cutting in Southern Finland. The volume of decayed Norway spruce (Picea abies (L.) H. Karst.) timber and pulpwood was determined by deducting the volumes of these assortments (as recorded on the measurement certificate) from the volume of the standing trees. To obtain the economic loss, the volume of decayed wood was multiplied by the difference in stumpage prices between spruce timber of pulpwood and pine pulpwood. In the 17 stands of Buyer A the loss in timber volume caused by decay was 5.84% and the loss in stumpage price 2.84 Fmk/m3 (means weighted by volume). The corresponding figures in the 9 stands of Buyer B were 10.87% and 5.50 Fmk/m3, respectively.

At the mean stumpage price level for the felling season 1977-78 the losses in the stands m.f.c. mentioned above were 2.87% per unit price in the stands of Buyer A and 5.75% in the stands of Buyer B.

The PDF includes a summary in English.

  • Tuimala, ORCID ID:E-mail:
article id 5017, category Article
T. Raunemaa, A. Hautojärvi, P. Jartti, J. Laurén, V. Lindfors, J. Räisänen. (1979). Trace element analysis of sound and decayed Norway spruce (Picea abies) by XRF and NAA methods. Silva Fennica vol. 13 no. 1 article id 5017. https://doi.org/10.14214/sf.a14871

Ashed tree samples from sound and decayed Norway spruce (Picea abies (L.) H. Karst.) were studied by means of fast neutron activation analysis, and for comparison, also by X-ray fluorescence analysis. In fast neutron activation analysis, the following elements were detected: (Na), Mg, Al, Si, K, Ca, Mn, Rb, Sr and Ba, and according to the results of the X-ray fluorescence method the elements present in the wood samples were: K, Ca, Mn, Rb, Sr and Ba. A general diminishing was revealed by both methods in most elemental concentrations studied, with exception of K and Rb, when going from a sound tree to a decayed one. The use of the ratio of the amounts of potassium to calcium as an indication of the degree of decay is therefore proposed.

The PDF includes a summary in Finnish.

  • Raunemaa, ORCID ID:E-mail:
  • Hautojärvi, ORCID ID:E-mail:
  • Jartti, ORCID ID:E-mail:
  • Laurén, ORCID ID:E-mail:
  • Lindfors, ORCID ID:E-mail:
  • Räisänen, ORCID ID:E-mail:
article id 5004, category Article
Matti Kärkkäinen. (1978). Haapatukkien lahoisuus. Silva Fennica vol. 12 no. 3 article id 5004. https://doi.org/10.14214/sf.a14858
English title: Occurrence of decay in aspen logs.
Original keywords: haapa; tukki; laho; tyvitukit
English keywords: aspen; Populus tremula; logs; decay; butt logs

At three Finnish match factories 1,629 aspen logs were measured (see Kärkkäinen and Salmi 1978). When the estimation was based on the condition of the butt cross section of a log, less than half of the logs were sound without any discoloration or decay. Based on the condition of the top cross-section, the corresponding figure was a little higher than 50%. The logs with decay were bigger than those without it. There were relatively more butt logs among the logs with decay than among the totally sound logs.

The PDF includes a summary in Finnish.

  • Kärkkäinen, ORCID ID:E-mail:
article id 4997, category Article
Pasi Jartti. (1978). Tyvilahon määritysmenetelmistä. Silva Fennica vol. 12 no. 2 article id 4997. https://doi.org/10.14214/sf.a14851
English title: Measurement of internal decay in living trees.

The physical methods currently available for measuring the internal decay of living trees is examined in this study. Although this is mainly a review, it can be concluded that some measurements shed more light on the problem. Examination of ultrasonic methods reveals that the coupling of ultrasonic energy from the transducer to the tree is not efficient. Both impulse and ultrasonic testing work best with decayed and hollow trees. The electrical resistance measurements of stumps gave resistance values for sound wood 300–400 kΩ, for decayed and discoloured wood about 12 kΩ and for cambium about 12 kΩ. The neutron activation gives good results, and in particular it reveals nicely the increasing concentration of potassium in decayed wood. The internal decay of living trees was not examined.

The PDF includes a summary in Finnish.

  • Jartti, ORCID ID:E-mail:
article id 4865, category Article
Tauno Kallio. (1972). Esimerkki kuusikon lahovikaisuuden Etelä-Suomessa aiheuttamasta taloudellisesta menetyksestä. Silva Fennica vol. 6 no. 2 article id 4865. https://doi.org/10.14214/sf.a14668
English title: An example on the economic loss caused by decay in growing Norway spruce timber in Southern Finland.

A growing stand of Norway spruce (Picea abies (L.) H. Karst.) marked for cutting was investigated in the winter of 1971–72 in Helsinki in Southern Finland in order to determine the economic loss caused by decay. Taking a sample from growing spruce trees with increment borer is not a reliable method of determining the frequency of decay. The decayed stems were twice measured for assortment cutting into lengths; the first time disregarding the decay and the second time doing the actual assortment cutting according to the grade of timber. The direct economic loss caused by decay was 13% of the price for standing timber. The indirect loss may be as great as the direct loss.

The PDF includes a summary in English.

  • Kallio, ORCID ID:E-mail:
article id 4861, category Article
Tauno Kallio, Yrjö Norokorpi. (1972). Kuusikon tyvilahoisuus. Silva Fennica vol. 6 no. 1 article id 4861. https://doi.org/10.14214/sf.a14664
English title: Butt rot in a Norway spruce stand.

The study was carried out in a Norway spruce (Picea abies (L.) H. Karst.) stand in Southern Finland which was to be clear-cut due to decay. The species composition and incidence of decay fungi were investigated from the cut surfaces of the stumps. In addition, the colour and size of the decayed spot was observed.

About 28% of the total number of trees were decayed. Fomes annosus (Heterobasidion annosum) was the most common decay fungus. It was identified from 75% of the decayed trees, and was the sole agent in 43% of these trees. Armillaria mellea was the second commonest decay fungus. It decayed trees mostly in combination with Fomes annosus. The most common colours of the decay produced by F. annosus were reddish or yellowish brown. The decay caused by A. mellea was blackish brown. The causative agent cannot be reliably identified on the basis of the colour of the decayed part.

The PDF includes a summary in English.

  • Kallio, ORCID ID:E-mail:
  • Norokorpi, ORCID ID:E-mail:
article id 4858, category Article
Tauno Kallio. (1972). Erään 10-vuotiaan hybridihaapametsikön lahovikaisuus. Silva Fennica vol. 6 no. 1 article id 4858. https://doi.org/10.14214/sf.a14661
English title: Decay in a ten-year old stand of hybrid aspen.
Original keywords: hybridihaapa; sienitaudit; laho; bakteerit

A ten-year old stand of hybrid aspen (Populus tremula x Populus tremuloides), growing in Southern Finland on about 1.5 ha of Oxalis-Myrtillus type (OMT) soil and affected by crown blight, was examined in 1971. The study revealed that almost all trees, both those removed by thinning and the remaining growing stock, were decayed. A number of bacteria, Fungi imperfecti species and ascomycetous fungi were isolated from the discoloured heartwood of the affected trees. No fungus of the Bacidiomycetes was found in the discoloured wood material.

The PDF includes a summary in English.

  • Kallio, ORCID ID:E-mail:
article id 4848, category Article
Matti Kärkkäinen. (1971). Lahon leviäminen puunkorjuun aiheuttamista kuusen runko- ja juurivaurioista. Silva Fennica vol. 5 no. 3 article id 4848. https://doi.org/10.14214/sf.a14650
English title: Decay following logging injury in stems and roots of Norway spruce.

The material of 78 damaged Norway spruce (Picea abies (L.) H. Karst.) trees was gathered in Southern Finland in order to clarify the advance of decay. The harvesting which had caused the scars had been carried out 12 years earlier and at the moment of the investigation the growing stand was 110 years old. It was noticed that the variables used could explain only a few per cent of the variation of the advance of decay. It was concluded that the only important thing in practice is whether the injuries are in roots or in stems.

The PDF includes a summary in English.

  • Kärkkäinen, ORCID ID:E-mail:
article id 7572, category Article
Tauno Kallio, Pekka Tamminen. (1974). Decay of spruce (Picea abies (L.) Karst.) in the Åland Islands. Acta Forestalia Fennica no. 138 article id 7572. https://doi.org/10.14214/aff.7572

In 1972, all Norway spruce (Picea abies (L.) H. Karst.) trees of a minimum 7 cm diameter at breast height growing in the sample plots of the Sixth National Forest Inventory were examined on the main island of Aland, Finland. The soundness of standing trees was estimated by means of external characteristics and increment borer chips. The trees were then felled and measured. They were cut into lengths, and the type and extent of decay were studied.

30% of the trees examined was affected by butt rot, ca. 3% by wound decay. A comparison of the results with those of the Sixth National Forest Inventory justifies the estimate that in Aland 23% of spruce trees exceeding 7 cm in diameter at 1.3 m had butt rot.

The proportion of decayed trees in the cubic volume was 31%. Decayed wood material accounted for 5% of the volume including bark. Butt rot increased towards the mature stands. The reduction in the number of timber trees due to decay was 14.5%, in their volume 21.5%, and in the volume of sulphite pulpwood 12%. The share of sulphate pulpwood increased from 1 to 10%. The total reduction in usable wood was 6.3%. The stumpage price of the trees fell by 10.3%. As the degree of decay increased the increment percentage of the trees decreased. The most common cause of butt rot was Fomes annosus (Heterobasidion annosum) found in 46% of the number of decayed trees. Armillaria mellea was found in 16%. Bacteria were found in 50% of the decayed trees.

The PDF includes a summary in Finnish.

  • Kallio, ORCID ID:E-mail:
  • Tamminen, ORCID ID:E-mail:
article id 7570, category Article
Antti Isomäki, Tauno Kallio. (1974). Consequences of injury caused by timber harvesting machines on the growth and decay of spruce (Picea abies (L.) Karst.). Acta Forestalia Fennica no. 136 article id 7570. https://doi.org/10.14214/aff.7570

The study material was collected from 10 localities in South Finland in 1971–72. The material comprised 816 damaged Norway spruce (Picea abies (L.) H. Karst.) trees with a total of 978 injuries.

Decay (discoloration) spread upward from the damaged point was about three times as fast as downward. The mean rate of advance upward was 21 cm/year. The decay spreading at the quickest rate started from above-ground root collar injuries. The size of the damaged area (surface area, width and depth) correlated positively with the rate of increase in decay initiated by the injury. For the first 10 years the decay advanced at the same rate after which the advance became slower though not ceasing. Damage produced in the early summer caused a faster spread of decay than that produced in the late summer or winter. The rate of advance was the greater the larger the stem involved. When decay started from trunk damage its rate of advance was greater the faster the growth of the trees. With a better soil type, the rate of advance in decay increased. Fertilization increased the rate of advance.

The widest stem injuries reduced tree growth by about one-third, and severed roots by nearly half of the growth of trees where the width of the injuries was 0–4 cm. Fomes annosus (Heterobasidion annosum) infected spruce injuries especially in the southern coastal district. The farthest tips of discoloration proved in most cases to be sterile. The most common fungus isolated from these sites was Stereum sanguinolentum.

The PDF includes a summary in Finnish.

  • Isomäki, ORCID ID:E-mail:
  • Kallio, ORCID ID:E-mail:
article id 4576, category Article
Bo-Eric Blumenthal. (1942). Studier angående aspens förekomst och egenskaper i Finland. Silva Fennica no. 56 article id 4576. https://doi.org/10.14214/sf.a9080
English title: Distribution and properties of aspen in Finland.

Aspen (Populus tremula L.) is a common tree in Finland, and has been used, for instance, in matchstick industry. However, there has been little studies on its distribution and properties. In this study, 142 sample trees in different forest site types in Valtimo and Onkamo in Eastern Finland were measured in detail in 1935.

According to the results, during the first 10 years aspens height growth is fastest of the Finnish tree species surpassing, for instance, Scots pine (Pinus sylvestris L.) and birch (Betula sp.) . The diameter growth is similar to Scots pine up to the age of 50 years, after which the growth of aspen exceeds Scots pine. Branchless portion of the stem compared to the height of the tree increases until it reaches about 50% of the height of the tree. In poorer sites aspen is prone to decay.

Aspen regenerates easily both by root shoots and seeds. If root shoots are left to grow, the mother tree should be free of decay. In general, seedlings are of better quality. Good quality aspen stands require thinning and a rich forest type. If an old aspen stand has decay, the trees should be ring-barked and the site regenerated with a new tree species.

The article includes an abstract in German.

  • Blumenthal, ORCID ID:E-mail:

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