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Articles containing the keyword 'cement'.

Category: Research article

article id 166, category Research article
Kim Pingoud, Johanna Pohjola, Lauri Valsta. (2010). Assessing the integrated climatic impacts of forestry and wood products. Silva Fennica vol. 44 no. 1 article id 166. https://doi.org/10.14214/sf.166
Managed forests serve as a store of carbon (C) and a renewable source of energy and materials. By using forest products as substitutes for fossil fuels or non-renewable materials, emissions from fossil C sources can be displaced. The efficiency of emissions displacement depends on the product, its lifecycle and the fossil-fuel based reference system that is substituted. Forest management practices have an impact on C stocks in biomass and on the annual supply of products and their mix. There are trade-offs between sequestering C stocks in forests and the climatic benefits obtained by sustainable forest harvesting and using wood products to displace fossil C emissions. This article presents an integrated, steady-state analysis comparing various equilibrium states of managed forests and wood product pools that represent sustainable long-term forestry and wood-use strategies. Two climatic indicators are used: the combined C stock in forests and wood products and the fossil C emissions displaced annually by harvested wood products. The study indicates that long-term strategies could be available that are better according to both indicators than forestry practices based on the existing silvicultural guidelines in Finland. These strategies would involve increasing the basal area and prolonging rotations to produce more sawlogs. Further, the climate benefits appear to be highest in case the sawlog supply is directed to production of long-lived materials substituting for fossil-emission and energy intensive materials and recycled after their useful life to bioenergy.
  • Pingoud, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland ORCID ID:E-mail: kim.pingoud@vtt.fi (email)
  • Pohjola, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Valsta, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 460, category Research article
Hong Ling, Sandhya Samarasinghe, G. Don Kulasiri. (2009). Modelling variability in full-field displacement profiles and Poisson ratio of wood in compression using stochastic neural networks. Silva Fennica vol. 43 no. 5 article id 460. https://doi.org/10.14214/sf.460
Vertical and horizontal displacement profiles in compression parallel-to-grain in a 20 x 20 mm area (30 x 21 or 630 points) in the Tangential–Longitudinal (T–L) and Radial Longitudinal (R–L) sections of small wood columns were obtained from digital image correlation applied to simultaneously captured images of the two surfaces. These consisted of 21 displacement realisations of 30 points along the length of the specimen. They revealed considerable local variations. Stochastic neural networks were successfully developed to simulate trends and noise across and along a specimen in both displacements as well as Poisson ratios in T–L and R–L sections for two selected load levels of 20kN and 40kN. These networks specifically embed noise characteristics extracted from data to generate realistic displacement and Poisson ratio realisations with inherent variability. Models were successfully validated using independent data extracted based on bootstrapping method with high accuracy with R2 ranging from 0.79 to 0.91. The models were further validated successfully using a second approach involving Confidence Intervals generated from the data extracted from the models. Models and experimental results revealed that for 20kN load, both vertical and horizontal displacements in T–L section were less heterogeneous across the specimen (smaller vertical shearing and horizontal strain, respectively) than those in the R–L section. For the 40kN load, both displacement profiles in the T–L section were less noisy and more compact than those for the 20kN load indicating less heterogeneity due to compaction of structure. In the R–L section, larger vertical shearing and horizontal strains persisted at 40 kN load. Poisson ratio decreased with load and it was nonlinear in both sections but T–L section showed much less noise across the specimen than the R–L section.
  • Ling, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Canterbury, New Zealand ORCID ID:E-mail:
  • Samarasinghe, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Canterbury, New Zealand ORCID ID:E-mail: sandhya.samarasinghe@lincoln.ac.nz (email)
  • Kulasiri, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, Canterbury, New Zealand ORCID ID:E-mail:
article id 384, category Research article
Jorge Cancino, Joachim Saborowski. (2005). Comparison of randomized branch sampling with and without replacement at the first stage. Silva Fennica vol. 39 no. 2 article id 384. https://doi.org/10.14214/sf.384
Randomized Branch Sampling (RBS) is a multistage sampling procedure using natural branching in order to select samples for the estimation of tree characteristics. Usually, sampling units are selected with unequal probabilities. Conventional RBS uses sampling with replacement (SWR) for repeated sampling on the first stage, and the sample size equals 1 on all subsequent stages, thus resulting in n so-called sample paths. When the sampling fraction is large multiple selections of first stage units are likely. Sampling without replacement (SWOR) at the first stage is an alternative that is expected to increase efficiency of the procedure. In this case, the second stage sample size m must be larger than 1 to enable unbiased variance estimation. In the present study, a theoretical and an empirical comparison of the conventional RBS and the SWOR variant was accomplished. Requiring a certain precision of the RBS estimation, the conventional RBS method is mostly more time-consuming than the variant with SWOR at the first stage. Only if m = 1 is chosen as second stage sample size for the SWOR RBS, this is often more time-consuming. In those cases, conventional RBS is up to 5% cheaper. In general, the larger m is, the more expensive is conventional RBS compared with the variant with swor at the first stage. The smaller the ratio of the variance between the primary units to the total variance of the estimate, the larger is the advantage of the SWOR variant. Generally, it can be shown that the gain of efficiency by SWOR is larger in case of weak correlations between auxiliary and target variable.
  • Cancino, Facultad de Ciencias Forestales, Universidad de Concepción, Chile ORCID ID:E-mail: jcancino@udec.cl (email)
  • Saborowski, Institut für Forstliche Biometrie und Informatik, Georg-August-Universität Göttingen, Germany ORCID ID:E-mail:
article id 380, category Research article
Tapani Repo, Janne Laukkanen, Raimo Silvennoinen. (2005). Measurement of the tree root growth using electrical impedance spectroscopy. Silva Fennica vol. 39 no. 2 article id 380. https://doi.org/10.14214/sf.380
The non-destructive evaluation of plant root growth is a challenge in root research. In the present study we aimed to develop electrical impedance spectroscopy (EIS) for that purpose. Willows (Salix myrsinifolia Salisb.) were grown from cuttings in a hydroponic culture in a growth chamber. Root growth was monitored at regular intervals by a displacement method and compared with the EIS parameters of the plants. To measure its impedance spectrum (IS) (frequency range from 40 Hz to 340 kHz) each plant was set in a measuring cell filled with a solution of the hydroponic culture. The IS was measured using a two-electrode measuring system. A silver needle electrode was connected to the stem immediately above the immersion level and a platinum wire was placed in the solution. The measurements were repeated twice weekly for a root growth period of one month. The IS of the entity consisting of a piece of stem, roots and culture solution were modelled by means of an electric circuit consisting of two ZARC-Cole elements, one constant-phase element, and a resistor. On the plant basis, an increase in root volume by growth correlated with a reduction in the sum of resistances in the ZARC-Cole elements (mean Pearson’s correlation coefficient r = –0.70).
  • Repo, The Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: tapani.repo@metla.fi (email)
  • Laukkanen, University of Joensuu, Department of Physics, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Silvennoinen, University of Joensuu, Department of Physics, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 630, category Research article
S. Samarasinghe, G. D. Kulasiri. (2000). Displacement fields of wood in tension based on image processing: Part 2. Crack-tip displacements in mode-I and mixed-mode fracture. Silva Fennica vol. 34 no. 3 article id 630. https://doi.org/10.14214/sf.630
Near tip displacement fields for tensile loaded cracked rubber and wood with a crack parallel-, perpendicular-to-grain, and a parallel-to-grain crack inclined 30°, 45°, and 60° to the load axis were obtained from digital image correlation (DIC). Theoretical displacements were also obtained for rubber and wood using isotropic and orthotropic fracture theory, respectively. The results showed that DIC can reveal fine details of the nature of displacements and the influences of crack tip in both rubber and wood. Experimental crack tip displacements for wood compare well with theory; particularly, when load is perpendicular-to-grain. Some anomalies were found in the tip displacements in the direction of the tracheids due to the unique nature of their behaviour not accounted for by theory. Mixed-mode crack tip displacement fields for wood clearly showed the increasing influence of crack angle on the displacements, and the displacements perpendicular to crack compared very well with theory. The displacements parallel to crack showed some variations owing to the involvement of tracheids.
  • Samarasinghe, Lincoln University, Appl. Computing, Mathematics and Statistics Group, P.O. Box 84, Canterbury, New Zealand ORCID ID:E-mail:
  • Kulasiri, Lincoln University, Appl. Computing, Mathematics and Statistics Group, P.O. Box 84, Canterbury, New Zealand ORCID ID:E-mail: kulasird@tui.lincoln.ac.nz (email)

Category: Review article

article id 73, category Review article
Timo Kuuluvainen, Tuomas Aakala. (2011). Natural forest dynamics in boreal Fennoscandia: a review and classification. Silva Fennica vol. 45 no. 5 article id 73. https://doi.org/10.14214/sf.73
The aim here was to review and summarize the findings of scientific studies concerning the types of forest dynamics which occur in natural forests (i.e. forests with negligible human impact) of boreal Fennoscandia. We conducted a systematic search for relevant studies from selected reference databases, using search terms describing the location, structure and processes, and degree of naturalness of the forest. The studies resulting from these searches were supplemented with other known works that were not indexed in the databases. This procedure yielded a total of 43 studies. The studies were grouped into four types of forest dynamics according to the information presented on the characteristics of the native disturbance-succession cycle: 1) even-aged stand dynamics driven by stand-replacing disturbances, 2) cohort dynamics driven by partial disturbances, 3) patch dynamics driven by tree mortality at intermediate scales (> 200 m2) and 4) gap dynamics driven by tree mortality at fine scales (< 200 m2). All four dynamic types were reported from both spruce and pine dominated forests, but their commonness differed. Gap dynamics was most commonly reported in spruce forests, and cohort dynamics in pine forests. The studies reviewed provide the best obtainable overall picture of scientific findings concerning the characteristics and variability of the unmanaged boreal forest dynamics in Fennoscandia. The results demonstrate that the unmanaged Fennoscandian forests are characterized by more diverse and complex dynamics than has traditionally been acknowledged.
  • Kuuluvainen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi (email)
  • Aakala, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:

Category: Research note

article id 1661, category Research note
Āris Jansons, Linda Robalte, Roberts Čakšs, Roberts Matisons. (2016). Long-term effect of whole tree biomass harvesting on ground cover vegetation in a dry Scots pine stand. Silva Fennica vol. 50 no. 5 article id 1661. https://doi.org/10.14214/sf.1661
Highlights: After 47 years, whole tree harvesting (WTH) increased richness of ground cover species compared to conventionally managed stands; Higher occurrence of the oligotrophic species after WTH suggested reduction of soil nutrient content, hence formation of different plant community; WTH, apparently, facilitated recovery of species typical for later successional stages.

Long-term (47 years) effect of experimental whole tree harvesting (WTH) with a heavy soil scarification on ground cover vegetation was assessed in a dry nutrient-poor Scots pine (Pinus sylvestris L.) stand in Latvia. Neighbouring conventionally managed young (10 years) and mature (119 years) stands of the same type were used for comparison. Higher species richness was observed in the WTH stand compared to conventionally managed young and mature stands (24, 18 and 16 species, respectively), likely due to the profound disturbance. The Shannon diversity index was higher in the young than in the WTH and mature stands (2.36, 1.77 and 1.63, respectively); still, the composition and structure of ground cover vegetation in WTH was more similar to the mature stand. Nevertheless, the occurrence of oligotrophic species in the WTH stand suggested decreased soil nutrient content and potential development of different plant community. Hence, such method might be considered for restoration of oligotrophic stands. Nevertheless, the period of 47 years appeared sufficient for the ground cover vegetation to recover after the WTH.

  • Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: aris.jansons@silava.lv
  • Robalte, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: robalte.l@gmail.com (email)
  • Čakšs, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: chakijs95@gmail.com
  • Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: roberts.matisons@silava.lv

Category: Article

article id 5395, category Article
Mirja Kortesharju, Jouko Kortesharju. (1989). Studies on epiphytic lichens and pine bark in the vicinity of a cement works in northern Finland. Silva Fennica vol. 23 no. 4 article id 5395. https://doi.org/10.14214/sf.a15553

The element content (Ca, Mg, K, Na, Fe, Mn, Zn, Cu, Pb, S) of Scots pine (Pinus sylvestris L.) bark and Bryoria lichens, as well as the occurrence and coverage of epiphytic lichens and the length of Bryoria species, were studied in the vicinity of Kolari cement works, NW Finland. Fruticose Bryoria species had the highest coverage on pine trunks at a distance of 2 km or more from the cement works. At a distance of 1 km the foliose – or even crustose – Parmeliopsis species were most abundant, while nearer to the works lichens were almost completely absent. The length of Bryoria was reduced at distances of less than 2 km from the cement works. The calcium content in Bryoria species increased very steeply close to the works; by a factor of 60 at a distance of 1 km compared to 16 km. No corresponding increase in other elements was observed near the cement works. All the elements studied in pine bark showed a significant negative correlation with distance, and a significant positive correlation with the calculated dust deposition levels. There were only minor differences between the north and south of the pine trunks, or the side facing or away from the works. Pine bark analysis is recommended for element accumulation studies.

The PDF includes an abstract in English.

  • Kortesharju, ORCID ID:E-mail:
  • Kortesharju, ORCID ID:E-mail:

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