Current issue: 53(3)

Under compilation: 53(4)

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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles containing the keyword 'fire'.

Category: Research article

article id 7746, category Research article
Jānis Donis, Māra Kitenberga, Guntars Šņepsts, Roberts Matisons, Juris Zariņš, Āris Jansons. (2017). The forest fire regime in Latvia during 1922–2014. Silva Fennica vol. 51 no. 5 article id 7746. https://doi.org/10.14214/sf.7746
Highlights: Climate effects and human influence on forest fire activity in Latvia was assessed using time-series analysis; Drought conditions during summer season had the strongest effect on fire activity of tested climatic variables; Negative trends and spatial distribution pattern of fire activity suggests of prevailing human influence on forest fire regime over the 20th century.

Fire as disturbance of forests has an important ecological and economical role in boreal and hemiboreal forests. The occurrence of forest fires is both climatically and anthropogenically determined and shifts in fire regimes are expected due to climate change. Although fire histories have been well documented in boreal regions, there is still insufficient information about fire occurrence in the Baltic States. In this study, spatio-temporal patterns and climatic drivers of forest fires were assessed by means of spatial and time-series analysis. The efficiency of Canadian Fire Weather (FWI) indices as indicators for fire activity was tested. The study was based on data from the literature, archives, and the Latvian State Forest service database. During the period 1922–2014, the occurrence and area affected by forest fires has decreased although the total area of forest land has nearly doubled, suggesting improvement of the fire suppression system as well as changes in socioeconomic situation. The geographical distribution of forest fires revealed two pronounced clusters near the largest cities of Riga and Daugavpils, suggesting dominance of human causes of ignitions. The occurrence of fires was mainly influenced by drought. FWI appeared to be efficient in predicting the fire occurrence: 23–34% of fires occurred on days with a high or extremely high fire danger class, which overall had a relative occurrence of only 4.3–4.6%. During the 20th century, the peak of fire activity shifted from May to April, probably due to global warming and socioeconomic reasons. The results of this study are relevant for forest hazard mitigation and development of fire activity prediction system in Latvia.

  • Donis, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: janis.donis@silava.lv
  • Kitenberga, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: mara.kitenberga@gmail.com (email)
  • Šņepsts, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: guntars.snepsts@silava.lv
  • Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv
  • Zariņš, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: juris.zarins@silava.lv
  • Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
article id 7723, category Research article
Mihails Čugunovs, Eeva-Stiina Tuittila, Ida Sara-Aho, Laura Pekkola, Jari Kouki. (2017). Recovery of boreal forest soil and tree stand characteristics a century after intensive slash-and-burn cultivation. Silva Fennica vol. 51 no. 5 article id 7723. https://doi.org/10.14214/sf.7723
Highlights: Soil organic matter stocks have still not fully recovered after a century of stand succession and passive recovery after slash-and-burn period; Historical slash-and-burn stands feature higher live birch and standing dead wood volume than controls; If passive rewildening is used, Fennoscandian boreal forests need more than a century to regain naturalness.

Passive rewildening of forest ecosystems is commonly used for rehabilitating degraded habitats closer to their natural origin in addition to costly active restoration measures. However, it is not clear if passive processes are effective and how long the recovery of main ecosystem properties takes. We investigate the recovery of forest soil and tree stand characteristics a century after cessation of slash-and-burn cultivation, a major historical intensive disturbance regime that was applied widely in boreal zone of Finland until late 1800s. We systematically sampled soil and tree stand parameters within former slash-and-burn and nearby control areas. Humus layer thickness and soil organic matter (SOM) stocks were still lower in the historical slash-and-burn than in control areas. Slash-and-burn areas also had a larger volume of live birch trees and a higher standing dead wood volume than control areas. Accordingly, organic matter (humus layer thickness and SOM stocks) correlated negatively with birch standing live tree volume. Combined OM stock in humus and uppermost 10 cm mineral soil layer was positively correlated with lying dead wood volume. Overall, we observed clear recovery of several natural properties but we also found that a century after cessation of frequent anthropogenic burnings, clear legacies of disturbance in the above- and below-ground parts of boreal ecosystem were evident. Our results indicate that if only passive rewildening is applied as a restoration measure, the full recovery of boreal forest is slow and the effects of historical land-use may persist for over hundred years in soil and tree properties.

  • Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: mihails.cugunovs@uef.fi (email)
  • Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
  • Sara-Aho, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: ida.sara-aho@mhy.fi
  • Pekkola, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: laura.pekkola@gmail.com
  • Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi
article id 1666, category Research article
Mareike Wieczorek, Alexei Kolmogorov, Stefan Kruse, Inga Jacobsen, Ingmar Nitze, Anatoly N. Nikolaev, Ingo Heinrich, Luidmila A. Pestryakova, Ulrike Herzschuh. (2017). Disturbance-effects on treeline larch-stands in the lower Kolyma River area (NE Siberia). Silva Fennica vol. 51 no. 3 article id 1666. https://doi.org/10.14214/sf.1666
Highlights: Disturbances are an important shaping factor of larch stands at lower Kolyma; Youngest larch stands have the highest population densities and highest growth rates; Saplings grow clustered, irrespective of the underlying disturbance regime; Mixed climate-disturbance signals make it difficult to infer future treeline processes.

Tree stands in the boreal treeline ecotone are, in addition to climate change, impacted by disturbances such as fire, water-related disturbances and logging. We aim to understand how these disturbances affect growth, age structure, and spatial patterns of larch stands in the north-eastern Siberian treeline ecotone (lower Kolyma River region), an insufficiently researched region. Stand structure of Larix cajanderi Mayr was studied at seven sites impacted by disturbances. Maximum tree age ranged from 44 to 300 years. Young to medium-aged stands had, independent of disturbance type, the highest stand densities with over 4000 larch trees per ha. These sites also had the highest growth rates for tree height and stem diameter. Overall lowest stand densities were found in a polygonal field at the northern end of the study area, with larches growing in distinct “tree islands”. At all sites, saplings are significantly clustered. Differences in fire severity led to contrasting stand structures with respect to tree, recruit, and overall stand densities. While a low severity fire resulted in low-density stands with high proportions of small and young larches, high severity fires resulted in high-density stands with high proportions of big trees. At water-disturbed sites, stand structure varied between waterlogged and drained sites and latitude. These mixed effects of climate and disturbance make it difficult to predict future stand characteristics and the treeline position.

  • Wieczorek, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany ORCID ID:E-mail: mareike.wieczorek@awi.de
  • Kolmogorov, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia ORCID ID:E-mail: kilatroooon@gmail.com
  • Kruse, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany ORCID ID:E-mail: Stefan.Kruse@awi.de
  • Jacobsen, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany ORCID ID:E-mail: Inga.Jacobsen@awi.de
  • Nitze, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Geography, University of Potsdam, 14476 Potsdam, Germany ORCID ID:E-mail: Ingmar.Nitze@awi.de
  • Nikolaev, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia; Melnikov Permafrost Institute of the Siberian Branch of RAS, 677000 Yakutsk, Russia ORCID ID:E-mail: yktnan@rambler.ru
  • Heinrich, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany ORCID ID:E-mail: heinrich@gfz-potsdam.de
  • Pestryakova, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia ORCID ID:E-mail: lapest@mail.ru
  • Herzschuh, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany ORCID ID:E-mail: Ulrike.Herzschuh@awi.de (email)
article id 1718, category Research article
Mihails Čugunovs, Eeva-Stiina Tuittila, Lauri Mehtätalo, Laura Pekkola, Ida Sara-Aho, Jari Kouki. (2017). Variability and patterns in forest soil and vegetation characteristics after prescribed burning in clear-cuts and restoration burnings. Silva Fennica vol. 51 no. 1 article id 1718. https://doi.org/10.14214/sf.1718
Highlights: Soil parameter variability is similar across sites of different disturbance type; Variability of understory vegetation biomass and cover is higher and more different between sites than soil variability; Sites studied here reflect well the assumed disturbance-type gradient based on PCA; Sampling six forest sites per treatment should provide good statistical power to capture the differences in soil organic matter stocks.

Forest ecological restoration by burning is widely applied to promote natural, early-successional sites and increase landscape biodiversity. Burning is also used as a forest management practice to facilitate forest regeneration after clearcutting. Besides the desired goals, restoration burnings also affect soil biogeochemistry, particularly soil organic matter (SOM) and related soil carbon stocks but the long-term effects are poorly understood. However, in order to study these effects, a reliable estimate of spatial variability is first needed for effective sampling. Here we investigate spatial variability of SOM and vegetation features 13 years after burnings and in combination with variable harvest levels. We sampled four experimental sites representing distinct management and restoration treatments with an undisturbed control. While variability of vegetation cover and biomass was generally higher in disturbed sites, soil parameter variability was not different between the four sites. The joint ecological patterns of soil and vegetation parameters across the whole sample continuum support well the prior assumptions on the characteristic disturbance conditions within each of the study sites. We designed and employed statistical simulations as a means to plan prospective sampling. Sampling six forest sites for each treatment type with 30 independent soil cores per site would provide enough statistical power to adequately capture the impacts of burning on SOM based on the data we obtained here and statistical simulations. In conclusion, we argue that an informed design-based approach to documenting the ecosystem effects of forest burnings is worth applying both through obtaining new data and meta-analysing the existing.

  • Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: mihails.cugunovs@uef.fi (email)
  • Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
  • Mehtätalo, University of Eastern Finland, School of Computing, Science Park, Länsikatu 15, P.O. Box 111, 80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0002-8128-0598 E-mail: lauri.mehtatalo@uef.fi
  • Pekkola, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: laura.pekkola@gmail.com
  • Sara-Aho, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: ida.sara-aho@mhy.fi
  • Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi
article id 1207, category Research article
Olli-Pekka Tikkanen, Irina A. Chernyakova. (2014). Past human population history affects current forest landscape structure of Vodlozero National Park, Northwest Russia. Silva Fennica vol. 48 no. 4 article id 1207. https://doi.org/10.14214/sf.1207
Highlights: In large scale (0–20 km), the proportion of spruce in forest stands was positively affected by distance from old villages. This relationship was non-linear with a threshold distance of 15 km; In small scale (0–5 km), old villages affected tree species composition and age structure of forests. Effect on age structure was the strongest on stands growing on mineral soils.
The information about location and size of past human settlements can give new insights into the analysis of landscape structures. Vodlozero National Park (NP) is one the largest strictly protected areas in Northwestern Europe. We mapped the location of historic villages, which were abandoned in 1958, and studied the effect of past human activity in the forest landscape in two different scales using forest survey data. We assessed the possible change in age, volume and tree species composition from the edge of open fields up to the distance of 5 km from villages. We made a larger landscape analysis using a grid of forest stands covering the whole northern part of the NP. The past human activity was clearly visible in the present forest landscape. Distance from villages affected age, volume and tree species composition of the forest stands. This effect was the strongest within the first two kilometers from the villages. At the level of whole northern NP, the proportion of spruce markedly increased after approximately 15 km from the nearest old village. The changes in the forests surrounding the villages were most likely the result of the intensive use of wood for different commodities needed in households and farming, in addition to short rotation slash and burn agriculture. If the occurrence of forest fires was more frequent closer to villages than in more remote areas, it can well explain the observed pattern in the abundance of spruce in the larger landscape that is less tolerant to fire than pine.
  • Tikkanen, Department of Biology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland (Current: School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland) & Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia ORCID ID:E-mail: Olli-Pekka.Tikkanen@uef.fi (email)
  • Chernyakova, Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia ORCID ID:E-mail: irina.chernyakova@onego.ru
article id 47, category Research article
Iulian Dragotescu, Daniel D. Kneeshaw. (2012). A comparison of residual forest following fires and harvesting in boreal forests in Quebec, Canada. Silva Fennica vol. 46 no. 3 article id 47. https://doi.org/10.14214/sf.47
Residual forests are a key component of post-burned areas creating structure within burns and providing habitat and seed sources. Yet, despite their importance to biodiversity and ecosystem processes there is little information on how similar or different residuals in burned landscape are to harvested landscapes. Our goal was to examine and compare the density, size, shape, and spatial arrangement of residual forest vegetation after fire and clearcutting. We evaluated residual forest in two locations within the boreal mixedwood region of Quebec, Canada using aerial photo interpretation and ArcGIS 9.1 software. We found residual stands to be larger and more abundant in harvested zones relative to sites affected by fire. Differences with respect to shape and spatial arrangement of residual forest were also observed among disturbance types. Factors such as proximity to watercourses, watercourse shape, and physiography affected residual abundance and spatial distribution. Residual forest in harvested zones tended to be more elongated with greater edge due to rules governing forest operations. Despite greater quantity of residual forest in harvested areas than fires, managers should still be prudent as the surrounding forest matrix is reduced in many managed landscapes.
  • Dragotescu, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada ORCID ID:E-mail: idragot@hotmail.com (email)
  • Kneeshaw, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada ORCID ID:E-mail:
article id 44, category Research article
Anabel Aparecida de Mello, Leif Nutto, Karla Simone Weber, Carlos Eduardo Sanquetta, Jorge Luis Monteiro de Matos, Gero Becker. (2012). Individual biomass and carbon equations for Mimosa scabrella Benth. (bracatinga) in southern Brazil. Silva Fennica vol. 46 no. 3 article id 44. https://doi.org/10.14214/sf.44
Mimosa scabrella Benth. is an important native species of southern Brazil widely used for energy and promising for reforestation carbon offsets. Quantification of biomass and carbon stock is valuable for both purposes. From a forest inventory conducted in southern Brazil, data of M. scabrella were analyzed. Thirty sample trees were felled, excavated and weighed in the field and brought to laboratory for biomass and carbon determination. The total aboveground biomass represented 85% of the tree biomass, while roots corresponded to 15%. Correlation matrix of diameter at 1.3 m height (D), tree height (H) versus total and compartment biomass (P) indicated strong association between tree dimensions and biomasses. Five regression models were tested and equations were fitted to data of five biomass compartments and total tree biomass. The best fitting model for total biomass was P = –0.49361 + 0.034865 x D2H whereas for the partial biomass of the compartments was lnP = β0 + β1 x ln(D) + β2 lnH. Carbon concentration was statistically significantly different in foliage than in other compartments. Three approaches of calculating carbon stocks were evaluated and compared to actual data: 1) Estimated total biomass x weighted mean carbon concentration; 2) Estimated partial (compartment) biomass x compartment average carbon concentration; and 3) Carbon regression equations. No statistical difference was detected among them. It was concluded that biomass equations fitted in this study were accurate and useful for fuelwood and carbon estimations.
  • de Mello, Federal University of Sergipe, Brazil ORCID ID:E-mail:
  • Nutto, Federal University of Paraná, Brazil ORCID ID:E-mail: lnutto.ufpr@gmail.com (email)
  • Weber, Federal University of Paraná ORCID ID:E-mail:
  • Sanquetta, Carlos Eduardo Sanquetta ORCID ID:E-mail:
  • Monteiro de Matos, Jorge Luis Monteiro de Matos ORCID ID:E-mail:
  • Becker, University of Freiburg, Institute of Forest Utilization and Work Science, Germany ORCID ID:E-mail:
article id 77, category Research article
Annie Claude Bélisle, Sylvie Gauthier, Dominic Cyr, Yves Bergeron, Hubert Morin. (2011). Fire regime and old-growth boreal forests in central Quebec, Canada: an ecosystem management perspective. Silva Fennica vol. 45 no. 5 article id 77. https://doi.org/10.14214/sf.77
Boreal forest management in Eastern Canada has caused depletion and fragmentation of old-growth ecosystems, with growing impacts on the associated biodiversity. To mitigate impacts of management while maintaining timber supplies, ecosystem management aims to narrow the gap between natural and managed landscapes. Our study describes the fire history and associated natural old-growth forest proportions and distribution of a 5000 km2 area located in the black spruce-feather moss forest of central Quebec. We reconstructed a stand-origin map using archival data, aerial photos and dendrochronology. According to survival analysis (Cox hazard model), the mean fire cycle length was 247 years for the 1734–2009 period. Age-class distribution modelling showed that old-growth forests were present on an average of 55% of the landscape over the last 275 years. The mean fire size was 10 113 ha, while most of the burned area was attributable to fires larger than 10 000 ha, leading to old-growth agglomerations of hundreds of square kilometres. In regards to our findings, we propose ecosystem management targets and strategies to preserve forest diversity and resilience.
  • Bélisle, Centre for Forest Research, Université du Québec à Montréal, Montréal, Québec, Canada ORCID ID:E-mail: annieclaude_b@hotmail.com (email)
  • Gauthier, Laurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, Sainte-Foy, Québec, Canada ORCID ID:E-mail:
  • Cyr, Institut Québécois d’Aménagement de la Fort Feuillue, Université du Québec en Outaouais, Ripon, Québec, Canada ORCID ID:E-mail:
  • Bergeron, Centre for Forest Research, Université du Québec à Montréal, Montréal, Québec, Canada & NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec, Canada ORCID ID:E-mail:
  • Morin, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada ORCID ID:E-mail:
article id 32, category Research article
Susete Marques, Jordi Garcia-Gonzalo, José G. Borges, Brigite Botequim, M. Manuela Oliveira, José Tomé, Margarida Tomé. (2011). Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal. Silva Fennica vol. 45 no. 1 article id 32. https://doi.org/10.14214/sf.32
Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.
  • Marques, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail: smarques@isa.utl.pt (email)
  • Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Borges, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Botequim, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Oliveira, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
article id 32, category Research article
Susete Marques, Jordi Garcia-Gonzalo, José G. Borges, Brigite Botequim, M. Manuela Oliveira, José Tomé, Margarida Tomé. (2011). Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal. Silva Fennica vol. 45 no. 1 article id 32. https://doi.org/10.14214/sf.32
Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.
  • Marques, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail: smarques@isa.utl.pt (email)
  • Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Borges, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Botequim, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Oliveira, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
  • Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal ORCID ID:E-mail:
article id 31, category Research article
Jeovanna Lowe, David Pothier, Jean-Pierre L. Savard, Ghislain Rompré, Mathieu Bouchard. (2011). Snag characteristics and cavity-nesting birds in the unmanaged post-fire northeastern Canadian boreal forest. Silva Fennica vol. 45 no. 1 article id 31. https://doi.org/10.14214/sf.31
We studied the availability and characteristics of snags and their use by cavity-nesting birds in the northeastern part of the Canadian boreal forest. We built up two long-term (> 200 years) chronosequences following time since the last fire in the unmanaged boreal forest of northeastern Québec, one in the balsam fir-white birch domain (southern region) and one in the spruce-mosses domain (northern region). We then sampled and characterized snags and live trees in 30 stands from each of these two chronosequences. We also looked for nest cavities on all sampled snags, performed bird inventories by point counts, and calculated tree mortality rate from permanent sample plots. Results show that mortality rates follow a U-shaped pattern, with more snags of large diameter (> 20 cm DBH) in young (< 50 years) and in old (> 200 years) forests. In the latter, we also found more nest cavities than in any other age classes. Although abundance of primary cavity nesters (excavating species) did not vary among age classes, secondary cavity nesters (using cavities already available) tend to be more numerous in older forests. Our results highlight the capacity for young and old-growth forests to provide quality habitat for species that are dependent on large snags. Proper forest management should maintain a mosaic of different age forest stands, including snags, to promote biodiversity and provide important resources for resident bird species.
  • Lowe, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada ORCID ID:E-mail: jeovannalowe@gmail.com (email)
  • Pothier, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada ORCID ID:E-mail:
  • Savard, Wildlife Research, Science and Technology, Québec Region, 1141 Route de l’Église, P.O. Box 10100, Québec, Québec, G1V 4H5, Canada ORCID ID:E-mail:
  • Rompré, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada & Department of Biology and Health Sciences, 84 West South Street, Wilkes University, PA 18766, USA ORCID ID:E-mail:
  • Bouchard, Ministère des Ressources naturelles et de la Faune, Direction de l’Environnement et de la Protection des Forets, 880 Chemin Ste-Foy, Quebec, Québec, G1S 4X4, Canada ORCID ID:E-mail:
article id 173, category Research article
Erik Hellberg, Torbjörn Josefsson, Lars Östlund. (2009). The transformation of a Norway spruce dominated landscape since pre-industrial times in northern Sweden: the influence of modern forest management on forest structure. Silva Fennica vol. 43 no. 5 article id 173. https://doi.org/10.14214/sf.173
Logging history and the study of reference conditions in Scandinavian boreal forests has tended to focus on Scots pine dominated ecosystems. This paper presents a regional study of pre-industrial forest conditions and examines the effects of the industrial exploitation of ecosystems dominated by Norway spruce in northern Sweden. Historical records covering a period which preceded industrial logging in the study area (1917–1927) were used to obtain quantitative data on forest structure and influence of forest fires. These data were compared with a modern data set (2003) to analyse changes due to the industrial transformation of the forest. The early 20th century landscape was dominated by old, multi-cohorted spruce forests and mixed coniferous forests. It was found that fire affected both the structure and composition of the landscape. In post-burnt areas, even-aged forests dominated by deciduous species were the principal forest type. Between the early and modern data sets, profound changes in tree-species composition and age structure were documented. While the total volume of deciduous species increased substantially, the coverage of forests dominated by deciduous species decreased. There was also a significant increase in pine-dominated forests and in the total volume of pine. The industrial transformation of the studied landscapes has had profound effects on the structure of spruce forests, but much less so on deciduous forests. The study concludes that the present forest structure is a function of past management regimes, and that future transformations of the landscape will continue, thus affecting the natural variability and biodiversity of the forests.
  • Hellberg, Tunstigen 10, SE-831 43 Östersund, Sweden ORCID ID:E-mail:
  • Josefsson, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden ORCID ID:E-mail: torbjorn.josefsson@svek.slu.se (email)
  • Östlund, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
article id 414, category Research article
Markku Larjavaara, Timo Kuuluvainen, Heidi Tanskanen, Ari Venäläinen. (2004). Variation in forest fire ignition probability in Finland. Silva Fennica vol. 38 no. 3 article id 414. https://doi.org/10.14214/sf.414
We examined climate-caused spatio-temporal variation of forest fire ignition probability in Finland based on empirical ignition experiments and 37 years of meteorological data from 26 meteorological stations scattered across Finland. First, meteorological data was used in order to estimate the variation in forest fuel moisture content with the model of the Finnish forest fire risk index. Second, based on data from empirical ignition experiments, fuel moisture content was linked with forest fire ignition probability. In southern Finland average forest fire ignition probability typically peaks in late May and early June, whereas in the northern part of the country the peak occurs at the end of June. There was a three-fold difference in the average annual ignition probability between the north-eastern part (3%) and south-western part of the country (9%). The observed differences in fire ignition probability suggest that the characteristics of the natural fire regime also vary considerably in the southern versus the northern part of the country.
  • Larjavaara, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: markku.larjavaara@helsinki.fi (email)
  • Kuuluvainen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Tanskanen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Venäläinen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 414, category Research article
Markku Larjavaara, Timo Kuuluvainen, Heidi Tanskanen, Ari Venäläinen. (2004). Variation in forest fire ignition probability in Finland. Silva Fennica vol. 38 no. 3 article id 414. https://doi.org/10.14214/sf.414
We examined climate-caused spatio-temporal variation of forest fire ignition probability in Finland based on empirical ignition experiments and 37 years of meteorological data from 26 meteorological stations scattered across Finland. First, meteorological data was used in order to estimate the variation in forest fuel moisture content with the model of the Finnish forest fire risk index. Second, based on data from empirical ignition experiments, fuel moisture content was linked with forest fire ignition probability. In southern Finland average forest fire ignition probability typically peaks in late May and early June, whereas in the northern part of the country the peak occurs at the end of June. There was a three-fold difference in the average annual ignition probability between the north-eastern part (3%) and south-western part of the country (9%). The observed differences in fire ignition probability suggest that the characteristics of the natural fire regime also vary considerably in the southern versus the northern part of the country.
  • Larjavaara, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: markku.larjavaara@helsinki.fi (email)
  • Kuuluvainen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Tanskanen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Venäläinen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 559, category Research article
Juho Pennanen. (2002). Forest age distribution under mixed-severity fire regimes – a simulation-based analysis for middle boreal Fennoscandia. Silva Fennica vol. 36 no. 1 article id 559. https://doi.org/10.14214/sf.559
A simulation model was used to study the age structure of unmanaged forest landscapes under different fire regimes. Stand age was defined as the age of the oldest tree cohort in a stand. When most fires are not stand-replacing, the theoretical equilibrium stand age distribution is either bell-shaped or bimodal and dominated by old age-classes. Old-growth forests (oldest cohort > 150 y) dominate the landscape unless fires are both frequent and severe. Simulation results and analytical calculations show that if a regime of frequent fires (about every 50 y) maintains landscapes dominated by old-growth forests, then old-growth dominance persists when the number of fires is decreased, despite the associated increase in fire severity. Simulation results were applied to Pinus sylvestris-dominated landscapes of middle boreal Fennoscandia, which according to empirical results were dominated by old-growth forests when fires were frequent during the 19th century. Since the changes in the fire regime can be plausibly explained by changes in the number of human-caused ignitions, old-growth forests have evidently also dominated the landscapes earlier when fires were less frequent. The simulation model is used to produce plausible age distributions of middle boreal Fennoscandian forest landscapes under different historical fire regimes. In summary, the frequency of large-scale disturbance alone predicts forest landscape dynamics poorly, and the roles played by fire severity and residual stands need to be considered carefully. Maintaining and restoring old-growth structures is essential to regaining the natural variability of Fennoscandian forest landscapes.
  • Pennanen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: juho.pennanen@helsinki.fi (email)
article id 558, category Research article
Tuomo Wallenius. (2002). Forest age distribution and traces of past fires in a natural boreal landscape dominated by Picea abies. Silva Fennica vol. 36 no. 1 article id 558. https://doi.org/10.14214/sf.558
Forest age distribution and occurrence of traces of past fires was studied in a natural Picea abies -dominated landscape in the Onega peninsula in north-west Russia. Forest age (maximum tree age) was determined and charcoal and fire scars were searched for in 43 randomly located study plots. In 70% of the study plots (30/43) trees older than 200 years existed. The largest 50-year age class consisted of plots with 251–300 year old forests. Traces of fires were found in all types of study plots, in forests on mineral soil as well as on peatlands. However, fire has been a rare disturbance factor, as traces of fires could not be found in 35% of the study plots (15/43). Estimated from the forest age class distribution, the fire rotation time for the whole area has been at least 300 years, but possibly considerably longer. This fire rotation time is much longer than fire history studies (largely based on examination of fire scars) commonly have reported for the average time between successive fires in Fennoscandia and Northwest Russia. The results suggest that the often stated generalisations about the importance and natural frequency of fire disturbance in boreal forests do not apply in landscapes dominated by Picea abies.
  • Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 56, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: tuomo.wallenius@helsinki.fi (email)
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 675, category Research article
Per Linder, Peter Jonsson, Mats Niklasson. (1998). Tree mortality after prescribed burning in an old-growth Scots pine forest in northern Sweden. Silva Fennica vol. 32 no. 4 article id 675. https://doi.org/10.14214/sf.675
Tree mortality and input of dead trees were studied after a prescribed burning in a forest reserve in northern Sweden. The stand was a multi-layered old-growth forest. The overstorey was dominated by Scots pine (Pinus sylvestris L.) and the understorey consisted of mixed Scots pine and Norway spruce (Picea abies L. Karst.). Ground vegetation was dominated by ericaceous dwarf-shrubs and feathermosses. The stand has been affected by six forest fires during the last 500 years. The prescribed burning was a low intensity surface fire that scorched almost 90% of the ground. Tree mortality for smaller pines and spruces (DBH < 10 cm) was over 80% in the burned parts of the reserve. For larger pines, 10–50 cm DBH, mortality showed a decreasing trend with increasing diameter, from 14% in class 10–20 cm DBH to 1.4% in class 40–50 cm DBH. However, pines with DBH ≥ 50 cm had a significantly higher mortality, 20%, since a high proportion of them had open fire scars containing cavities, caused by fungi and insects, which enabled the fire to burn inside the trunks and hollow them out. The fire-induced mortality resulted in a 21 m3 ha–1 input of dead trees, of which 12 m3 ha–1 consisted of trees with DBH ≥ 30 cm. An increased mortality among larger trees after low-intensity fires has not previously been described in Fennoscandian boreal forests, probably owing to a lack of recent fires in old-growth stands. However, since large pines with open fire scars were once a common feature in the natural boreal forest, we suggest that this type of tree mortality should be mimicked in forestry practices aiming to maintain and restore natural forest biodiversity.
  • Linder, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Jonsson, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Niklasson, Southern Swedish Forest Research Centre, SLU, Box 49, S-230 53 Alnarp, Sweden ORCID ID:E-mail:

Category: Review article

article id 36, category Review article
Tuomo Wallenius. (2011). Major decline in fires in coniferous forests – reconstructing the phenomenon and seeking for the cause. Silva Fennica vol. 45 no. 1 article id 36. https://doi.org/10.14214/sf.36
Steep decline in forest fires about a century ago occurred in coniferous forests over large areas in North America and Fennoscandia. This poorly understood phenomenon has been explained by different factors in different regions. The objective of this study is to evaluate the validity of the four most commonly suggested causes of the decrease in forest fires: fire fighting, over-grazing, climate change and human influence. I compiled the available dendrochronological data and estimated the annually burned proportions of Pinus-dominated forests in four subcontinental regions during the past 500 years. These data were compared to the development of fire suppression, grazing pressure, climate and human livelihoods. The annually burned proportions declined over 90% in all studied regions. In three out of the four regions fires decreased decades before fire suppression began. Available drought data are annually well correlated with fires but could not explain the decrease of the level in annually burned areas. A rapid increase in the number of livestock occurred at the same time with the decrease in fires in the Western US but not in Fennoscandia. Hence, fire suppression in Central Fennoscandia and over-grazing in the Western US may have locally contributed to the reduction of burned areas. More general explanation is offered by human influence hypothesis: the majority of the past forest fires were probably caused by humans and the decrease in the annually burned areas was because of a decrease in human caused fires. This is in accordance with the old written records and forest fire statistics. The decrease in annually burned areas, both in Fennoscandia and the United States coincides with an economic and cultural transition from traditional livelihoods that are associated with high fire use to modern agriculture and forestry.
  • Wallenius, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland ORCID ID:E-mail: tuomo.wallenius@metla.fi (email)
article id 36, category Review article
Tuomo Wallenius. (2011). Major decline in fires in coniferous forests – reconstructing the phenomenon and seeking for the cause. Silva Fennica vol. 45 no. 1 article id 36. https://doi.org/10.14214/sf.36
Steep decline in forest fires about a century ago occurred in coniferous forests over large areas in North America and Fennoscandia. This poorly understood phenomenon has been explained by different factors in different regions. The objective of this study is to evaluate the validity of the four most commonly suggested causes of the decrease in forest fires: fire fighting, over-grazing, climate change and human influence. I compiled the available dendrochronological data and estimated the annually burned proportions of Pinus-dominated forests in four subcontinental regions during the past 500 years. These data were compared to the development of fire suppression, grazing pressure, climate and human livelihoods. The annually burned proportions declined over 90% in all studied regions. In three out of the four regions fires decreased decades before fire suppression began. Available drought data are annually well correlated with fires but could not explain the decrease of the level in annually burned areas. A rapid increase in the number of livestock occurred at the same time with the decrease in fires in the Western US but not in Fennoscandia. Hence, fire suppression in Central Fennoscandia and over-grazing in the Western US may have locally contributed to the reduction of burned areas. More general explanation is offered by human influence hypothesis: the majority of the past forest fires were probably caused by humans and the decrease in the annually burned areas was because of a decrease in human caused fires. This is in accordance with the old written records and forest fire statistics. The decrease in annually burned areas, both in Fennoscandia and the United States coincides with an economic and cultural transition from traditional livelihoods that are associated with high fire use to modern agriculture and forestry.
  • Wallenius, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland ORCID ID:E-mail: tuomo.wallenius@metla.fi (email)
article id 551, category Review article
Anders Dahlberg. (2002). Effects of fire on ectomycorrhizal fungi in Fennoscandian boreal forests. Silva Fennica vol. 36 no. 1 article id 551. https://doi.org/10.14214/sf.551
Fire, the primary natural disturbance factor in Fennoscandian boreal forests, is considered to have exerted major selection pressure on most boreal forest organisms. However, recent studies show that few ectomycorrhizal (EM) fungi appear to have evolved post-fire adaptations, no succession of EM fungi following fire is apparent after low intensity fires, and only two EM fungal taxa exclusively fruit at post-fire conditions. In this paper I review the present knowledge of effects of forest fire on EM fungal communities in Fennscandian boreal forests, put into perspective by a comparison from other parts of the world. Characteristically, these boreal forests consist of less than a handful of tree species, e.g. Scots pine and Norway spruce, while the below ground communities of EM fungi is impressively species rich with presently more than 700 known taxa. Commonly, forest fires in Fennoscandia have been of low intensity, with a considerable portion of the trees surviving and the organic humus layer partly escaping combustion. Hence, EM fungi appear to largely have evolved under conditions characterised by a more or less continuous presence of their hosts. In fact, the composition of EM fungi within a forest appear be more variable due to spatial variation than due to wildfire. However, in areas with high intensity burns and high tree mortality, most EM fungi may locally be killed. Thus, the legacy of EM fungi following wildfire depends on the survival of trees, which determine the potential for mycorrhizal growth, and the combustion and heating of the organic soil, which directly correlate to mortality of mycorrhizas. The questions if and to what degree fires may be of significance for yet unidentified spatiotemporal dynamics of EM fungal populations and communities are discussed. Recent experiments indicate a few EM fungi are favoured by high intensity burn conditions whereas others disappear. The consequences of wildfires in temperate conifer forests differ considerably from those in boreal forests. Wildfires in temperate conifer forests are typically high intensity stand-replacing fires that cause a total combustion of organic layers. Subsequently, pre-fire EM fungal communities are largely eradicated and a succession of post-fire EM fungi is initiated.
  • Dahlberg, Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: anders.dahlberg@artdata.slu.se (email)
article id 549, category Review article
Andrei Gromtsev. (2002). Natural disturbance dynamics in the boreal forests of European Russia: a review. Silva Fennica vol. 36 no. 1 article id 549. https://doi.org/10.14214/sf.549
In the European part of the Russian boreal zone the dynamics of pristine forests (taiga) has been studied by several generations of researchers. Many studies have examined the patterns and role of fire, windthrow, insect outbreaks and other natural disturbances. An attempt is made to provide a brief review of these studies. The reviewed studies show that lightning strikes were the only natural source of fires in taiga. The frequency of fires varied in various types of pristine landscape from 1–2 per century to 1–2 per millennium. Fires maintained a dynamic equilibrium between compositionally different forest communities or their certain ratio and areal occurrence. Fires favored the regeneration and recovery of pine forests and prevented the replacement of shade-intolerant species (e.g. pine) by shade-tolerant ones (e.g. spruce). Taiga forests generally displayed a mosaic pattern that varied from pioneer plant communities, growing in open burns, to climax communities that were extremely seldom affected by fire. The reviewed studies suggest that fires were a powerful ecological factor in pristine taiga, being largely responsible for the structure and spontaneous dynamics of forest communities. Windfalls were also common in pristine taiga landscapes and they regulated spontaneous dynamics in a gap-mosaic regime, which is most characteristic of spruce forests.
  • Gromtsev, Forest Research Institute, Karelian Research Centre of the Russian Academy of Sciences, P.O. Box 185610, Petrozavodsk, Pushkin st. 11, Russia ORCID ID:E-mail: gromtsev@karelia.ru (email)
article id 548, category Review article
Kevin C. Ryan. (2002). Dynamic interactions between forest structure and fire behavior in boreal ecosystems. Silva Fennica vol. 36 no. 1 article id 548. https://doi.org/10.14214/sf.548
This paper reviews and synthesizes literature on fire as a disturbance factor in boreal forests. Spatial and temporal variation in the biophysical environment, specifically, vegetative structure, terrain, and weather lead to variations in fire behavior. Changes in slope, aspect, elevation, and soil affect site energy and water budgets and the potential plant community. These terrain features also have a major influence on fire-caused disturbance through their role in determining moisture conditions and flammability of fuels on hourly, seasonal, and successional time-scales. On fine time scales (minutes to hours), changes in weather, specifically wind and relative humidity, significantly affect a fire’s intensity and aboveground effects. Normal seasonal changes in dryness and periodic drought influence fire intensity and severity principally by affecting the depth of burn and belowground effects. On decades-long time scales changes in vegetative structure affect the mass of fuel available for burning and therefore the potential energy that can be released during a fire. The severity of fire varies in time and space depending not only on the biophysical environment, but also on the location on the fire’s perimeter (head vs. flank vs. rear). Spatial and temporal variation in severity within a fire can have long-lasting impacts on the structure and species composition of post-fire communities and the potential for future disturbances. Characteristic temperature histories of ground, surface, and crown fires are used to illustrate variations in fire severity. A soil-heating model is used to illustrate the impact of varying depth of burn on the depth at which various fire effects occur in the soil profile. A conceptual model is presented for the effects of fire severity on fire-plant regeneration interactions. The conceptual model can be used by restoration ecologists to evaluate the differential effects of controlled or prescribed fires and wildfires and to plan and implement fire treatments to conserve biodiversity.
  • Ryan, USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, P.O. Box 8089, Missoula, Montana 59807, USA ORCID ID:E-mail: kryan@fs.fed.us (email)
article id 548, category Review article
Kevin C. Ryan. (2002). Dynamic interactions between forest structure and fire behavior in boreal ecosystems. Silva Fennica vol. 36 no. 1 article id 548. https://doi.org/10.14214/sf.548
This paper reviews and synthesizes literature on fire as a disturbance factor in boreal forests. Spatial and temporal variation in the biophysical environment, specifically, vegetative structure, terrain, and weather lead to variations in fire behavior. Changes in slope, aspect, elevation, and soil affect site energy and water budgets and the potential plant community. These terrain features also have a major influence on fire-caused disturbance through their role in determining moisture conditions and flammability of fuels on hourly, seasonal, and successional time-scales. On fine time scales (minutes to hours), changes in weather, specifically wind and relative humidity, significantly affect a fire’s intensity and aboveground effects. Normal seasonal changes in dryness and periodic drought influence fire intensity and severity principally by affecting the depth of burn and belowground effects. On decades-long time scales changes in vegetative structure affect the mass of fuel available for burning and therefore the potential energy that can be released during a fire. The severity of fire varies in time and space depending not only on the biophysical environment, but also on the location on the fire’s perimeter (head vs. flank vs. rear). Spatial and temporal variation in severity within a fire can have long-lasting impacts on the structure and species composition of post-fire communities and the potential for future disturbances. Characteristic temperature histories of ground, surface, and crown fires are used to illustrate variations in fire severity. A soil-heating model is used to illustrate the impact of varying depth of burn on the depth at which various fire effects occur in the soil profile. A conceptual model is presented for the effects of fire severity on fire-plant regeneration interactions. The conceptual model can be used by restoration ecologists to evaluate the differential effects of controlled or prescribed fires and wildfires and to plan and implement fire treatments to conserve biodiversity.
  • Ryan, USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, P.O. Box 8089, Missoula, Montana 59807, USA ORCID ID:E-mail: kryan@fs.fed.us (email)
article id 695, category Review article
Marja-Leena Päätalo. (1998). Factors influencing occurrence and impacts of fires in northern European forests. Silva Fennica vol. 32 no. 2 article id 695. https://doi.org/10.14214/sf.695
The return interval and number of fires vary, depending on the geographical location in interaction with climate, topography and amount of fuel. During recent decades, in northern Europe the number and severity of fires have been insignificant compared with Mediterranean region, in which fire return intervals may be 15–35 years, compared to the average of 60–120 years for boreal forests. This is partly due to the efficient system of fire protection in northern Europe, but is mainly due to the less favourable climate for fire and the smaller human impact on ignition of forest fires. The consequences of fire are related to both site and stand characteristics, site being the most important factor controlling the stability of stands. Dry sites being more flammable and likely to ignite are associated with high risk of fire. In northern Europe, due to the interaction between species and site, the role of species difference in risk of fire damage is not clear. In southern Europe, fire risk cannot be explained by differences between tree species. There, other vegetation (shrubs, etc.) is of major importance for the risk of fire. Management of forests can, to some degree, alter the risk and the occurrence of fire. In northern Europe, logging may have compensated for fire occurrence by decreasing the amount of fuel. In addition, forest roads act as fire-breaks and facilitate fire-fighting. On the contrary, in southern Europe the risk of fire has been found to increase because the traditional forest uses and management have decreased, which increases the accumulation of fuel. However, it is not yet possible to quantify and compare the effect of management in absolute terms. Currently, some tools, such as fire-risk indices, remote sensing and GIS-based techniques, are available for prediction of fire risk in some areas. For example, fire-risk indices are most suitable for areas, like northern Europe, which have a low fire risk. In high-risk areas, such as southern Europe, more sophisticated techniques are needed for assessment of the risk. In the future, assuming global warming at northern latitudes (2 x CO2 climate), the risk of fire damage could also increase in northern Europe. Therefore, to allow the various locational and silvicultural factors to be assessed on the European level, an integrated risk model is needed.
  • Päätalo, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland ORCID ID:E-mail:

Category: Research note

article id 7771, category Research note
Māra Kitenberga, Roberts Matisons, Āris Jansons, Jānis Donis. (2018). Teleconnection between the Atlantic sea surface temperature and forest fires in Latvia and Estonia. Silva Fennica vol. 52 no. 1 article id 7771. https://doi.org/10.14214/sf.7771
Highlights: Forest fire activity in Latvia and Estonia was related to conditions in the Atlantic; Teleconnections differed regionally; Negative correlation between number of fires in Estonia and SST in the North Atlantic was detected; Area of forest fires in Estonia and activity of fires in Latvia were positively correlated with SST in the Baltic, North and Mediterranean Seas in summer.

Forest fire is one of the natural disturbances, which have important ecological and socioeconomical effect. Although fire activity is driven by weather conditions, during past two centuries forest fires have been strongly anthropogenically controlled. In this study, teleconnection between sea surface temperature (SST) in the Atlantic, which influences climate in Europe, and forest fire activity in Latvia and Estonia was assessed using “Climate explorer” web-tool. Factors affecting number and area of forest fires in Latvia and Estonia differed, suggesting regional specifics. In Estonia, the number of fires correlated with the SST in the North Atlantic in spring and summer, which affects the inflow of cool and dry air masses from the Arctic, hence the aridity and burnability. The area of fires in Estonia and in Latvia was associated with increased SST in Baltic Sea and near the European coast in summer, which likely were consequences of occurrence of warm high-pressure systems in summer, causing hot and dry conditions. Nevertheless, the observed teleconnections could be used to predict activity of forest fires in Latvia and Estonia.

  • Kitenberga, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: mara.kitenberga@gmail.com (email)
  • Matisons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv
  • Jansons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Donis, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: janis.donis@silava.lv
article id 569, category Research note
Heikki Kauhanen. (2002). Occurrence of fires in the eastern Saariselkä area, north-west Russia. Silva Fennica vol. 36 no. 1 article id 569. https://doi.org/10.14214/sf.569
The occurrence of fires was studied in the eastern Saariselkä area, North-West Russia, by using satellite images and topographical maps. In total, more than 330 burned areas were pinpointed in the study area of 4770 km2. Old burns were concentrated in the eastern part of the study area, but young burns were more common in the west. Sites affected by fires in the more recent past were much smaller than those burnt over earlier. The abundance of burns along rivers and the border surveillance road provided evidence of human impact. The most significant changes in the landscape were found in the eastern part of the study area, where spruce forests had been replaced by birch woodlands.
  • Kauhanen, Finnish Forest Research Institute, Kolari Research Station, Muoniontie 21 A, FIN-95900 Kolari, Finland ORCID ID:E-mail: heikki.kauhanen@metla.fi (email)
article id 569, category Research note
Heikki Kauhanen. (2002). Occurrence of fires in the eastern Saariselkä area, north-west Russia. Silva Fennica vol. 36 no. 1 article id 569. https://doi.org/10.14214/sf.569
The occurrence of fires was studied in the eastern Saariselkä area, North-West Russia, by using satellite images and topographical maps. In total, more than 330 burned areas were pinpointed in the study area of 4770 km2. Old burns were concentrated in the eastern part of the study area, but young burns were more common in the west. Sites affected by fires in the more recent past were much smaller than those burnt over earlier. The abundance of burns along rivers and the border surveillance road provided evidence of human impact. The most significant changes in the landscape were found in the eastern part of the study area, where spruce forests had been replaced by birch woodlands.
  • Kauhanen, Finnish Forest Research Institute, Kolari Research Station, Muoniontie 21 A, FIN-95900 Kolari, Finland ORCID ID:E-mail: heikki.kauhanen@metla.fi (email)

Category: Article

article id 7181, category Article
Eino Oinonen. (1967). Keltalieon (Lycopodium complanatum L.) itiöllinen uudistuminen Etelä-Suomessa kloonien laajuutta ja ikää koskevan tutkimuksen valossa. Acta Forestalia Fennica vol. 83 no. 3 article id 7181. https://doi.org/10.14214/aff.7181
English title: Sporal regeneration of ground pine (Lycopodium complanatum L.) in Southern Finland in the light of the dimensions and the age of its clones.

In an earlier paper of the author it was established that sporal regeneration of bracken fern (Pteridium aquilinum (L.) Kuhn.) is almost entirely connected with fire, and that the size of the bracken fern clones, distinguished by their characteristics, was related to the time of the fire. In previous studies has been found that also sporal regeneration of ground pine (Lycopodium complanatum L., now Diphasiastrum complanatum) is rare. The occurrence of several plant species were studied in relation to bracken fern in the earlier investigation. This paper reports findings concerning ground pine.

When the size-age problem of bracken fern was solved, parallel measurements of ground pine stand on the same site led to the solution of the size-age problem and sporal regeneration of ground pine. The linkage is also valid when the size of ground pine stands was compared to the dates of fires. The ground pine stands are very long-lasting. The stands are fragmented more easily than bracken fern by environmental factors, such as fires, and tend to form large patch clusters with time. Large individual stands reveal the rarity of sporal regeneration of ground pine. The resemblance with bracken fern clones indicate a common factor of regeneration, fire, and a very even spreading rate. Though considerable variation of the colour and structure of ground pine was observed, the circular stands were identical patch by patch.

The PDF includes a summary in English.

  • Oinonen, ORCID ID:E-mail:
article id 7180, category Article
Eino Oinonen. (1967). The correlation between the size of Finnish bracken (Pteridium aquilinum (L.) Kuhn.) clones and certain periods of site history. Acta Forestalia Fennica vol. 83 no. 2 article id 7180. https://doi.org/10.14214/aff.7180

In an earlier paper of the author it was established that bracken fern (Pteridium aquilinum (L.) Kuhn.) that the sporal regeneration of the species is almost entirely connected with fire, and that the size of the bracken fern clones, distinguished by their characteristics, was related to the time of the fire. The time of the fire was determined by the samples taken with auger from the trees on the sample plots. A large data on the occurrence of bracken fern was collected around Finland, but only part of it could be used in the previous study, as the trees of the site provided no means to find out it the site had been burned earlier.

In earlier studies, a mass occurrence of sporelings of bracken fern in England has been connected to cities bombed and burned during the World War II. In this study the data of the clones is connected to historical sources and the time of wars in Finland. The comparisons in this study have confirmed the results achieved by comparing the dimensions of the bracken clones to the fire dates. It was found that the wars have caused an increase in the regeneration frequency of bracken fern.

  • Oinonen, ORCID ID:E-mail:
article id 7180, category Article
Eino Oinonen. (1967). The correlation between the size of Finnish bracken (Pteridium aquilinum (L.) Kuhn.) clones and certain periods of site history. Acta Forestalia Fennica vol. 83 no. 2 article id 7180. https://doi.org/10.14214/aff.7180

In an earlier paper of the author it was established that bracken fern (Pteridium aquilinum (L.) Kuhn.) that the sporal regeneration of the species is almost entirely connected with fire, and that the size of the bracken fern clones, distinguished by their characteristics, was related to the time of the fire. The time of the fire was determined by the samples taken with auger from the trees on the sample plots. A large data on the occurrence of bracken fern was collected around Finland, but only part of it could be used in the previous study, as the trees of the site provided no means to find out it the site had been burned earlier.

In earlier studies, a mass occurrence of sporelings of bracken fern in England has been connected to cities bombed and burned during the World War II. In this study the data of the clones is connected to historical sources and the time of wars in Finland. The comparisons in this study have confirmed the results achieved by comparing the dimensions of the bracken clones to the fire dates. It was found that the wars have caused an increase in the regeneration frequency of bracken fern.

  • Oinonen, ORCID ID:E-mail:
article id 7479, category Article
Matti Franssila. (1958). Kulovaaran ja säätekijöiden välisestä riippuvuudesta. Acta Forestalia Fennica vol. 67 no. 5 article id 7479. https://doi.org/10.14214/aff.7479
English title: The dependence of forest fire danger on meteorological factors.
Original keywords: metsäpalot; ilmasto; kuivuus; maan kuivuus

The investigation is divided into statistical and experimental sections, the latter of which were conducted in a Vaccinium type Scots pine (Pinus sylvestris L.) stand with the aim of elucidating the interdependence of soil humidity and meteorological factors. The moisture content of pine needles and moss and wooden cylinders placed on the soil or slightly over the ground was determined by weighing. The results showed that there is correlation between the moisture content of the wooden cylinders and the relative humidity of air during the days without rain. Correlation between moisture content of pine needles and moss with the air was slightly poorer.

In the statistical section, based on meteorological observations made in the geophysical observatory at Sodankylä in Northern Finland in 1920-1943, and forest fire statistics of the area, forest fire days and days without forest fires were divided into 40 temperature-humidity groups. Of the 391 forest fires observed in the area, the cause of the fire was known in 353 cases, and 69% of these were caused by lightning. A forest fire danger index was calculated using the data. A sharp increase in the burned area when the index exceeded the limit k=0.3 seem to be explained by thunderstorms, which are the most notable cause of forest fires in the Sodankylä area.

The forest fire index was calculated also at four meteorological stations in different parts of the country using weather observations in 1927-1936. It appears that the number of days in which the k>0.1 decreases when proceeding northwards, obviously because of the shortening of the summer. On the other hand, the number of days in which k>0.3 increases towards the north.

The PDF includes a summary in English.

  • Franssila, ORCID ID:E-mail:
article id 7424, category Article
P. A. Ennevaara. (1954). Metsäpalot vuosina 1952-1953. Acta Forestalia Fennica vol. 61 no. 12 article id 7424. https://doi.org/10.14214/aff.7424
English title: Forest fires in 1952-1953 in Finland.

The statistics of forest fires in Finland expanded in 1952 to include uninsured forests, when previously the statistics included only fires in state forests and insured forest holdings. For private forests the material is collected by central forestry associations with the aid of district forestry boards, and for state forests by the Forest Service which also prepares the overall statistics on forest fires in the country. Forest fire statistics for 1952 and 1953 have been prepared on the basis of regional grouping by counties.

In 1952 a total of 299 forest fires were discovered, affecting a burnt area of 764 ha. Of these 20 were in state forests, burning 139 ha, and 279 in private forests, burning 625 ha. The average devastated area was 2.6 ha (in state forests 6.9 ha). This year was the easiest from the point of view of forest fires in the period between 1946-1953. The year 1953, on the other hand, was the worst of the period. The number of fires was only 216, but the burnt area was 8,955 ha. In state forests 87 fires devastated 8,624 ha. In private forests 129 fires burned 331 ha. The average area destroyed was 4.2 ha (in state forests 99.1 ha, and in private forests 2.6 ha). The largest fires on state forests were in the northernmost districts of the country.

The Silva Fennica issue 61 was published in honour of professor Eino Saari‘s 60th birthday.

  • Ennevaara, ORCID ID:E-mail:
article id 7414, category Article
Peitsa Mikola. (1954). Suomen maaseudun tulisijat. Acta Forestalia Fennica vol. 61 no. 2 article id 7414. https://doi.org/10.14214/aff.7414
English title: Rural fireplaces in Finland.
Original keywords: tulisijat; kiukaat; puun käyttö; Suomi
English keywords: fireplaces; firewood; Finland

Wood consumption in Finland in 1938-1939 was studied by investigating the wood consumption of aprroximately 2,000 farms. One of the surveys connected to the investigation studied fireplaces and heating equipment in rural districts, and recorded the types of fireplaces in the farms.

The majority of the rural fireplaces are rather old-fashioned and the technically best equipment are rare. The fireplaces in Eastern and Northern Finland are often more primitive than in Western and Southern Finland.

In Western Finland, where hard bread is common, the baking oven is lit 30-50 times a year. In Eastern Finland, where soft bread is baked, the oven is lit about 200 times a year. The sauna i heated about 40 times a year in the west, and 80 times a year in the east.

The PDF includes a summary in English.

  • Mikola, ORCID ID:E-mail:
article id 7414, category Article
Peitsa Mikola. (1954). Suomen maaseudun tulisijat. Acta Forestalia Fennica vol. 61 no. 2 article id 7414. https://doi.org/10.14214/aff.7414
English title: Rural fireplaces in Finland.
Original keywords: tulisijat; kiukaat; puun käyttö; Suomi
English keywords: fireplaces; firewood; Finland

Wood consumption in Finland in 1938-1939 was studied by investigating the wood consumption of aprroximately 2,000 farms. One of the surveys connected to the investigation studied fireplaces and heating equipment in rural districts, and recorded the types of fireplaces in the farms.

The majority of the rural fireplaces are rather old-fashioned and the technically best equipment are rare. The fireplaces in Eastern and Northern Finland are often more primitive than in Western and Southern Finland.

In Western Finland, where hard bread is common, the baking oven is lit 30-50 times a year. In Eastern Finland, where soft bread is baked, the oven is lit about 200 times a year. The sauna i heated about 40 times a year in the west, and 80 times a year in the east.

The PDF includes a summary in English.

  • Mikola, ORCID ID:E-mail:
article id 7413, category Article
V. Pöntynen. (1954). Tutkimuksia Suomen teollisuuden vuonna 1950 käyttämistä polttoaineista. Acta Forestalia Fennica vol. 61 no. 1 article id 7413. https://doi.org/10.14214/aff.7413
English title: Investigations into industrial fuel in Finland in 1950.

The use of imported fuels has increased in Finland, which has resulted in a growing disregard of domestic fuels, primarily firewood, on fuel market. This has affected forest management and economy of forest owners as well as diminishing the working opportunities in the countryside by decreasing the demand of small-sized timber. This investigation studies the fuel problem in the industrial field by a survey sent to all industrial plants in the country.

The different fuels were converted to the calorific value of pine firewood measured in piled cubic meters (p-m3, cu.m.). In 1950 the industry utilized 14.1 million cu.m piled measure of imported and domestic fuels. Of this 47% was domestic fuels and 53% imported fuels. The share of coal was 40%, wood waste almost 30%, and firewood 18%. The relatively small proportion of firewood suggests that it could be possible to increase the industrial demand for firewood. However, it should be noted that industry uses fuel mainly for power production, where imported fuels are highly effective. Forest industry used 2/3 of all domestic fuel.

According to the report, waste wood was cheapest kind of fuel for industry. It was, however, often the plant’s own waste material. The cost of coal at the mill was 60% of the corresponding price of firewood. The location of the industry affects greatly the price relations between domestic and imported fuels. Coal is cheaper close to the harbours and the coastline of the country. The state has supported firewood transportation by lower freight rates for firewood.

The PDF includes a summary in English.

  • Pöntynen, ORCID ID:E-mail:
article id 7405, category Article
Viljo Holopainen. (1950). Eräiden Suomen kaupunkien halkojen hankinta-alueet : markkinatieteellinen tutkimus. Acta Forestalia Fennica vol. 59 no. 1 article id 7405. https://doi.org/10.14214/aff.7405
English title: The firewood supply areas of four Finnish towns.

In the present investigation, the problems connected to demand of firewood are dealt with by studying the fuel markets of the three biggest towns in Finland – Helsinki, Turku and Tampere as well as those of Vaasa. The purpose of the investigation was to study the firewood supply areas in two time periods, in 1933-1939 and in 1945-1947, after the Second World War.

Railway and shipping were the most important ways for transporting firewood in 1933-1939. Towards the end of the period, road transport increased especially in Turku and in Vaasa. In 1945-47 almost 90% of the firewood transported to Helsinki, 60% to Tampere and Turku, and over 50% of the firewood transpors to Vaasa were carried by rail. One factor supporting rail transport was that the tariff policy of the State Railways gave preference to firewood transports.

The supply areas increased markedly from 1933-1939 to 1945-1947. Supply of firewood near the towns in the southern, southwestern and western parts of the country was small. Also, pulp industry began to use small-sized timber in 1930s, which increased competition of the wood. Coal and coke began to replace firewood in the 30s, but their use decreased during and after the war due to supply shortage.

The PDF includes a summary in English.

  • Holopainen, ORCID ID:E-mail:
article id 7401, category Article
Veijo Heiskanen. (1950). Tutkimuksia pinopuutavaran proomuun lastauksesta. Acta Forestalia Fennica vol. 58 no. 1 article id 7401. https://doi.org/10.14214/aff.7401
English title: Investigations on loading piled wood into barges.

In Finland, transportation of wood by vessels has decreased, but is still an important mode of transport especially for firewood. In 1941-1947, nearly 25% of the firewood procured by the State Fuel Board was transported by vessels. This investigation concentrates on loading of wood into barges, since the share of wages of total expenses is greatest in this phase. The loading work amounts to nearly 40% of the total wages.

Two methods of loading barges are used in Finland: loading from the shore and truck loading. This study concentrates on the more common method, loading from the shore. A time study was conducted on the different stages of loading and piling wood into barges, most of which is done by hand. Most time-consuming part of the work is transporting the logs to the barge with a wheelbarrow, comprising over 40% of the working time. Time required for loading firewood is almost twice as much as loading pulp wood. Recommendations for loading places and organization of work are given in the article to improve the efficiency of the work.

The PDF includes a summary in English.

  • Heiskanen, ORCID ID:E-mail:
article id 7337, category Article
Erkki K. Kalela. (1937). Vakuutetuissa metsissä vuosina 1925-34 sattuneista kuloista. Acta Forestalia Fennica vol. 46 no. 2 article id 7337. https://doi.org/10.14214/aff.7337
English title: Forest fires in the insured forests in Finland in 1925-1934.
Original keywords: metsäpalo; metsäpalovakuutus; kulo
English keywords: forest fire insucance

Total of 1,305 forest fires was ignited in 1925-1934 in the forests insured by the Metsänomistajain Keskinäinen Metsäpaloapuyhdistys (The Forest Owners' Mutual Forest Fire Insurance Company and the Keskinäinen Vakuutusyhtiö Sampo (The Sampo Mutual Insurance Company). The variation was large: from 34 fires in 1928 to 362 fires in 1933. The forest fires were most abundant in the county of Oulu and Häme. The average size of the burned areas varied from 2.4 hectares to 30.5 hectares. The area of forests that had forest fire insurance increased steadily from 2.2 million hectares in 1925 to 3,7 million hectares in 1934.

The PDF includes a summary in German.

  • Kalela, ORCID ID:E-mail:
article id 7336, category Article
R. Sarvas. (1937). Kuloalojen luontaisesta metsittymisestä : Pohjois-Suomen kuivilla kankailla suoritettu metsäbiologinen tutkielma. Acta Forestalia Fennica vol. 46 no. 1 article id 7336. https://doi.org/10.14214/aff.7336
English title: Natural regeneration of burned areas. Forest biological study in dry mineral soil sites in Northern Finland.

Natural regeneration has been common in Northern Finland, where forest fires have been usual, and the large areas make artificial regeneration expensive. The regeneration, and for instance tree species composition and density of the stand, cannot been controlled. In Northern Finland there is little demand for Betula sp. which is often abundant in the burnt areas. The unburned forests are generally Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) H. Karst.) dominated mixed forests with single Betula sp. trees.

The fire destroys birch for the most part in the Vaccinium site type, but the surviving trees produce enough seeds to regenerate the areas. The largest trees of Scots pine usually survive the fires. Pine has good seed years in the north only every 8th or 10th year. Spruce is totally destroyed in the forest fire and the seedlings grow poorly as primary species. The seedling stands are usually dominated by Scots pine and birch, but birch seedlings grow in batches, and do not hinder growth of pine. The drier Calluna site type stands are dominated by Scots pine. Birch seedlings may be abundant in the beginning, but most of them do not survive. Abundant emergent pine trees prevent the growth of seedlings especially in the dry site types, and they should be thinned to guarantee regeneration. Sowing results are better few years after the fire. The birch seedling should be removed from the seedling stands.

The PDF includes a summary in German.

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

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

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

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

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

  • Keränen, ORCID ID:E-mail:
article id 5567, category Article
Pekka Punttila, Yrjö Haila. (1996). Colonisation of a burned forest by ants in the southern Finnish boreal forest. Silva Fennica vol. 30 no. 4 article id 5567. https://doi.org/10.14214/sf.a8502

The colonisation of a burned clear-cut by ants in southern Finland was monitored using pitfall traps, artificial nest sites, and direct nest sampling from the ground and stumps. Clearcutting and fire seemed to have destroyed wood-ant colonies (Formica rufa group), and also other mature-forest species suffered from fire. Myrmica ruginodis Nylander was able to survive only in less severely burned moist sites, whereas it benefitted from the enhanced light conditions in a non-burned clear-cut. The fire resulted in an essentially ant-free terrain into which pioneering species immigrated. The mortality of nest-founding queens appeared to be high. The results supported the hypothesis that the pioneering species tend to be those that are capable of independent colony founding, followed by species founding nests through temporary nest parasitism. The succession of the burned clear-cut differed from that of the non-burned one, suggesting that habitat selection in immigration and priority effects, i.e. competition, introduce deterministic components in the successional pathways of boreal ant communities.

  • Punttila, ORCID ID:E-mail:
  • Haila, 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 5601, category Article
Jari Parviainen. (1996). Impact of fire on Finnish forest in the past and today. Silva Fennica vol. 30 no. 2–3 article id 5601. https://doi.org/10.14214/sf.a9246

Nearly every forest land in Finland has been burnt down by a wildfire at least once during the past 400–500 years. Slash and burn cultivation (1700–1920) was practised on 50–75 percent of Finland's forests, while prescribed burning (1920–1990) has been applied to 2–3 percent of the country's forests. Because of land-use changes and efficient fire prevention and control systems, the occurrence of wildfires in Finland has decreased considerably during the past few decades. Owing to the biodiversity and ecologically favourable influence of fire, the current tendency is to revive the use of controlled fire in forestry in Finland. Prescribed burning is used in forest regeneration and endeavours are being made to revert old conservation forests to the starting point of succession through forest fires.

  • Parviainen, ORCID ID:E-mail:
article id 5601, category Article
Jari Parviainen. (1996). Impact of fire on Finnish forest in the past and today. Silva Fennica vol. 30 no. 2–3 article id 5601. https://doi.org/10.14214/sf.a9246

Nearly every forest land in Finland has been burnt down by a wildfire at least once during the past 400–500 years. Slash and burn cultivation (1700–1920) was practised on 50–75 percent of Finland's forests, while prescribed burning (1920–1990) has been applied to 2–3 percent of the country's forests. Because of land-use changes and efficient fire prevention and control systems, the occurrence of wildfires in Finland has decreased considerably during the past few decades. Owing to the biodiversity and ecologically favourable influence of fire, the current tendency is to revive the use of controlled fire in forestry in Finland. Prescribed burning is used in forest regeneration and endeavours are being made to revert old conservation forests to the starting point of succession through forest fires.

  • Parviainen, ORCID ID:E-mail:
article id 5599, category Article
Vadim V. Gorshkov, Irene J. Bakkal. (1996). Species richness and structure variations of Scots pine forest communities during the period from 5 to 210 years after fire. Silva Fennica vol. 30 no. 2–3 article id 5599. https://doi.org/10.14214/sf.a9244

Postfire recovery of species diversity (including a number of species, entropy of species relative coverage (Shannon index of species diversity) was studied in lichen and green moss site types of Scots pine (Pinus sylvestris L.) forests in the central part of the Kola Peninsula. The results obtained indicate the difference in the dynamics of characteristics of biodiversity of forest components during postfire recovery. The stabilization of separate components of forest community varies in time from 5–15 to 120–140 years after the fire. Characteristics of the dwarf shrub and herb stratum recovered and stabilized 5–15 years after fire, while the complete stabilization of characteristics of moss-lichen cover is observed in community with fire ages of 90–140 years. Species richness of tree stratum recovered 120–140 years after fire. Time of complete stabilization of species richness of the community was estimated 120–140 years after fire. The size of the area over which characteristics of the biodiversity were estimated effected the mean values and, in most cases, the character of variation of studied characteristics. Over an area of 1 x 1 m dynamics of characteristics of species diversity coincide in forests of the studied types. Regardless of forest type within the area of 100 m2 species richness recovered 30 years after the fire (i.e. 3–5 times earlier than the establishment of the complete stabilization of the forest structure). That means that floristic composition of the forest remained unchanged from 30 to 210 years after the fire.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
article id 5599, category Article
Vadim V. Gorshkov, Irene J. Bakkal. (1996). Species richness and structure variations of Scots pine forest communities during the period from 5 to 210 years after fire. Silva Fennica vol. 30 no. 2–3 article id 5599. https://doi.org/10.14214/sf.a9244

Postfire recovery of species diversity (including a number of species, entropy of species relative coverage (Shannon index of species diversity) was studied in lichen and green moss site types of Scots pine (Pinus sylvestris L.) forests in the central part of the Kola Peninsula. The results obtained indicate the difference in the dynamics of characteristics of biodiversity of forest components during postfire recovery. The stabilization of separate components of forest community varies in time from 5–15 to 120–140 years after the fire. Characteristics of the dwarf shrub and herb stratum recovered and stabilized 5–15 years after fire, while the complete stabilization of characteristics of moss-lichen cover is observed in community with fire ages of 90–140 years. Species richness of tree stratum recovered 120–140 years after fire. Time of complete stabilization of species richness of the community was estimated 120–140 years after fire. The size of the area over which characteristics of the biodiversity were estimated effected the mean values and, in most cases, the character of variation of studied characteristics. Over an area of 1 x 1 m dynamics of characteristics of species diversity coincide in forests of the studied types. Regardless of forest type within the area of 100 m2 species richness recovered 30 years after the fire (i.e. 3–5 times earlier than the establishment of the complete stabilization of the forest structure). That means that floristic composition of the forest remained unchanged from 30 to 210 years after the fire.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
article id 5588, category Article
Vadim V. Gorshkov, Irene J. Bakkal, Natalie I. Stavrova. (1996). Postfire recovery of forest litter in Scots pine forests in two different regions of boreal zone. Silva Fennica vol. 30 no. 2–3 article id 5588. https://doi.org/10.14214/sf.a9233

Investigations carried out in the Kola peninsula (northern taiga) and in the South-western part of Western Siberia (southern taiga and forest-steppe) revealed identical course of the postfire restoration process of forest litter thickness in Scots pine (Pinus sylvestris L.) forests. Despite the differences in mean annual temperature (2°C) and other climatic characteristics the recovery time for thickness of forest litter in both regions amounts to 90–100 years after fire in pine forests of lichen site type and 120–140 years – in green moss type; the thickness of forest litter therewith corresponds 3–4 cm and 7–8 cm respectively. That mean that within the natural borders of pine forests, communities of a specific type possess uniform characteristics of restoration. On the basis of empirical data, it appears that the predicted increase of mean annual temperature of earth surface by (2°C) will not bring changes into the character of postfire recovery of forest litter thickness. It was shown that during the period of the recovery, which spans about 90 years after fire in pine forests of lichen and green moss-lichen site types and 140 years in ones of green moss site types, the rate of increasing of carbon store in the forest litter averaged 0.6 t ha-1 year-1, 0.1 t ha-1 year-1 and 0.2 t ha-1 year-1, respectively.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
  • Stavrova, ORCID ID:E-mail:
article id 5588, category Article
Vadim V. Gorshkov, Irene J. Bakkal, Natalie I. Stavrova. (1996). Postfire recovery of forest litter in Scots pine forests in two different regions of boreal zone. Silva Fennica vol. 30 no. 2–3 article id 5588. https://doi.org/10.14214/sf.a9233

Investigations carried out in the Kola peninsula (northern taiga) and in the South-western part of Western Siberia (southern taiga and forest-steppe) revealed identical course of the postfire restoration process of forest litter thickness in Scots pine (Pinus sylvestris L.) forests. Despite the differences in mean annual temperature (2°C) and other climatic characteristics the recovery time for thickness of forest litter in both regions amounts to 90–100 years after fire in pine forests of lichen site type and 120–140 years – in green moss type; the thickness of forest litter therewith corresponds 3–4 cm and 7–8 cm respectively. That mean that within the natural borders of pine forests, communities of a specific type possess uniform characteristics of restoration. On the basis of empirical data, it appears that the predicted increase of mean annual temperature of earth surface by (2°C) will not bring changes into the character of postfire recovery of forest litter thickness. It was shown that during the period of the recovery, which spans about 90 years after fire in pine forests of lichen and green moss-lichen site types and 140 years in ones of green moss site types, the rate of increasing of carbon store in the forest litter averaged 0.6 t ha-1 year-1, 0.1 t ha-1 year-1 and 0.2 t ha-1 year-1, respectively.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
  • Stavrova, ORCID ID:E-mail:
article id 5521, category Article
Taneli Kolström, Seppo Kellomäki. (1993). Tree survival in wildfires. Silva Fennica vol. 27 no. 4 article id 5521. https://doi.org/10.14214/sf.a15682

The survival of forest tree species in wildfires was examined on two burned stands. Norway spruce (Picea abies (L.) H. Karst.) and birches (Betula spp.) proved to be sensitive to the effects of wildfire; almost all individuals of these tree species were killed by the fires. Scots pine (Pinus sylvestris L.) was more tolerable to the effects of wildfire; i.e. one out of five Scots pines survived. Fire tolerance increased as tree size increased.

The PDF includes an abstract in Finnish.

  • Kolström, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
article id 5227, category Article
Harri Vasander, Tapio Lindholm. (1985). Tulen voimakkuus ja maanpinnan lämpötila kulotuksen aikana. Silva Fennica vol. 19 no. 1 article id 5227. https://doi.org/10.14214/sf.a15406
English title: Fire intensities and surface temperatures during prescribed burning.

Surface temperature during two prescribed burnings were measured in 1983 in Evo, Southern Finland. Surface temperatures in relation to the amount of slash burned, energy released during the fires, and the fire intensities were studied. The fire intensity was also measured during a third burn. The Lake Nimetön site was burned int the end of May. Due to the uneven distribution of slash, colonization by Calamagrostis arundinacea and the spring moisture, the burning was very uneven. Surface temperatures varied between 410–809°C and the intensity of fire was low (range 0–900 kW/m).

The fire intensity on the other sites burned in May was also low (880 kW/m). During the burn in August the surface temperatures varied between 701–869°C and the intensity of fire was moderate (1,170 kW/m). Slash was burned more evenly and more thoroughly due to the dryness of the site and slash and the fact that grasses and other herbs were not abundant.

The PDF includes a summary in Finnish.

  • Vasander, ORCID ID:E-mail:
  • Lindholm, ORCID ID:E-mail:
article id 5002, category Article
Antti Haapanen, Pertti Siitonen. (1978). Kulojen esiintyminen Ulvinsalon luonnonpuistossa. Silva Fennica vol. 12 no. 3 article id 5002. https://doi.org/10.14214/sf.a14856
English title: Forest fires in Ulvinsalo strict nature reserve in Northern Finland.

The study is the first report of a larger project concerning fire ecology in the Finnish boreal forests. Modern forestry has never been practiced in the Ulvinsalo strict nature reserve (2,500 ha) in Northern Finland in the county of Kuhmo. Forest fires have been uncommon because of mosaic of mineral and peat soils. The forests are mostly Norway spruce (Picea abies (L.) H. Karst.) dominated with Scots pine (Pinus sylvestris L.) often as the oldest trees of a stand. Forest fires were dated by counting annual rings from cambium to the fire scar in pines. 73 stands covering 1,207 ha were surveyed, over 80% of which was on mineral soil.

50% of the area had burned at least once during the life time of the present pine trees. 48 different forest fires were found, the first being from the year 1712 and the latest from 1969. The average time elapsed between the fires was about 82±43 years, and range 18–219 years. It was assumed that the stands where no fire scars were found, had, however, regenerated after fires but no fires have occurred since after that. In latter part of the 19th century 21 forest fires were dated, in the other half centuries only 4–9. This may have been caused by the increased human activity in the late 1800’s. The fire rotation of the area is 280 years, and spruce is almost the only tree species, which can regenerate in the present situation.

The PDF includes a summary in English.

  • Haapanen, ORCID ID:E-mail:
  • Siitonen, ORCID ID:E-mail:
article id 7023, category Article
August Renvall. (1919). Suojametsäkysymyksestä III. Metsän suojeleminen kuloilta. Acta Forestalia Fennica vol. 11 no. 2-3 article id 7023. https://doi.org/10.14214/aff.7023
English title: Protection forests III.

The third part of the six-article series about protection forest in Northern Finland describes prevention of forest fires in the pine timber line area. The article gives a proposal for a forest fire decree. According to the proposal, lighting a campfire should be prohibited in dry and windy times. Vegetation should be cleared around a campfire in the summertime. The local people should be obliged to help to extinguish any forest fire, and given compensation for the work. The compensation would be claimed from the person who lit the fire, if that is known. A fine is collected if forest fire breaks out by negligence. 

The article is divided in six parts. The parts II and III of the article series are included in the same PDF. A German summary is in a separate PDF.

  • Renvall, ORCID ID:E-mail:
article id 7023, category Article
August Renvall. (1919). Suojametsäkysymyksestä III. Metsän suojeleminen kuloilta. Acta Forestalia Fennica vol. 11 no. 2-3 article id 7023. https://doi.org/10.14214/aff.7023
English title: Protection forests III.

The third part of the six-article series about protection forest in Northern Finland describes prevention of forest fires in the pine timber line area. The article gives a proposal for a forest fire decree. According to the proposal, lighting a campfire should be prohibited in dry and windy times. Vegetation should be cleared around a campfire in the summertime. The local people should be obliged to help to extinguish any forest fire, and given compensation for the work. The compensation would be claimed from the person who lit the fire, if that is known. A fine is collected if forest fire breaks out by negligence. 

The article is divided in six parts. The parts II and III of the article series are included in the same PDF. A German summary is in a separate PDF.

  • Renvall, ORCID ID:E-mail:
article id 7535, category Article
Olli Heikinheimo. (1915). Einige Beobachtungen über die Aufarbeitung und Verwahrung des Brennholzes. Acta Forestalia Fennica vol. 4 no. 3 article id 7535. https://doi.org/10.14214/aff.7535
English title: Observations about manufacturing and storage of firewood.
Original keywords: Brennholz; Wassergehalt; Versuche

The moisture content of the wood has negative impact on transport, storage and use of wood, particularly this can be noticed on firewood. The moister the wood the harder is the transportation and storing. The high percentage of moisture also reduces the heating power of fire wood.

Drying of the wood of different tree species was studied at the forestry institute Tuomarniemi with following experiment setup: pines, spruces, birches, aspens and alders were logged and cut into one-meter split billets. Then they were dices according Huber’s formula. The wood was stacked in three similar ricks (stacks), varying the direction of the cut surface. The various tree species were distributed evenly to every rick. The split billets were weighted straight after manufacturing and after every month.

The wood dries fastest during spring and summer months. The direction of the cut surface of split billets in the rick makes no big differences in drying. The coniferous wood dries up to lower moisture content than broadleaved   woods.
  • Heikinheimo, ORCID ID:E-mail:
article id 7636, category Article
Kari Heliövaara, Rauno Väisänen. (1984). Effects of modern forestry on Northwestern European forest invertebrates: a synthesis. Acta Forestalia Fennica no. 189 article id 7636. https://doi.org/10.14214/aff.7636

The effects of modern forestry on northwest European forest invertebrates are summarized and analysed mainly on the basis of published literature. The direct influence of different practices including clear-cutting, thinning, burning-over, ploughing, changes in tree species composition of stands, fertilization, insecticides, pheromones and biological control are discussed from a forest zoological point of view. Also, the indirect effects of general changes in boreal forest dynamics, loss of primeval forests, cessation of natural fires and the dominance of young stands are described. The direct effects of different silvicultural practices on the species composition and diversity of forest invertebrates are usually considered to be striking but transient. However, when large areas are treated, the species associated with primeval forests, especially with the wood composition system in them, as well as the species associated with fires, seem to have drastically declined. In northwest Europe, efficient forestry has not caused such serious pest problems as is known from tropical countries or North America.

The PDF includes a summary in Finnish.

  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
article id 7625, category Article
Antti Turakka, Olavi Luukkanen, Suree Bhumibhamon. (1982). Notes on Pinus kesiya and P. merkusii and their natural regeneration in watershed areas of northern Thailand. Acta Forestalia Fennica no. 178 article id 7625. https://doi.org/10.14214/aff.7625

The aim of the present work was to clarify the structure of selected natural Pinus kesiya Royale ex Gord. And P. merkusii Jungh. et de Vriese stands, with particular attention on the amount and quality of naturally-occurring seedlings and young trees. Furthermore, basic information required in the management of pine stands in watershed areas of northern Thailand was obtained.

Large number of pine seedlings were found in P. kesiyana stands only. Two of the examined four localities where this species occurred also included various intermediary height classes under the mature trees. In dense stands the number of seedlings was generally smaller as compared with lower seed tree densities. Neither one of the two localities where P. Merkusii was investigated indicated sufficient natural regeneration. Young pines (over 5 m height) seemed to survive the frequent ground fires quite well, whereas younger seedlings were destroyed and the ground layer vigour was lowered in these cases.

In situ sowing experiments at the beginning of the dry season indicated a faster development and better survival of emerging P. Kesiya seedlings as compared to P. Merkusii. Soil preparation and exposure to sun decreased the survival of seedlings in both species. Utilization of natural regeneration and direct sowing of pines as a silvicultural method as well as the general significance of the two pine species in the succession of plant communities under the influence of forest fires is also discussed.

The PDF includes a summary in Finnish.

  • Turakka, ORCID ID:E-mail:
  • Luukkanen, ORCID ID:E-mail:
  • Bhumibhamon, ORCID ID:E-mail:
article id 4701, category Article
Veijo Heiskanen. (1960). Tutkimuksia koivuhalkojen painosta ja kosteudesta. Silva Fennica no. 108 article id 4701. https://doi.org/10.14214/sf.a9136
English title: Studies on the weight and moisture of split birch fuel wood.

The purpose of this investigation is to examine the weight and moisture of split birch fuel wood and to calculate its heat values. The weight was measured of 255 truck loads in six different locations during the winter 1959–1960. Moisture analysis was made of sample specimens collected from the loads.

The dry matter weight of the birch fuel wood was in an average 333 kg/m3 piled measure. The lowest measured weight was 319 and the highest 341 kg/m3 piled measure. The moisture content in the different parts of the pile varies distinctly. Driest wood is found in the middle of the pile. Wood in the top and bottom of the pile have about similar moisture content.

The manner of storage influences the drying process. The moisture content of open piles is 20.5%, of paper-covered piles 19.9% and roofed multiple-piles of split fuel wood 19.3%. The 2-year-old piles were dryer than 1-year-old ones. Higher percentages (25% and 20 %, respectively) than those measured in the study, are recommended for practical use. The heat value of the wood stored in a pile was in average 1,435 Mcal/m3 piled measure, and 1,455 Mcal/m3 piled measure sampled from a truck load.

The PDF includes a summary in English.

  • Heiskanen, ORCID ID:E-mail:
article id 7537, category Article
Yrjö Roitto. (1970). Fuelwood consumption in the city of Monrovia ( Liberia) in 1965. Acta Forestalia Fennica no. 103 article id 7537. https://doi.org/10.14214/aff.7537

This paper deals with fuelwood consumption in the city of Monrovia (Liberia) in 1965. Buyers of fuelwood were interviewed at market places, relevant data were recorded, and the average size of fuelwood bundles was measured by applying Archimedes Law.

The results showed that the annual average consumption of fuelwood per caput was 1.3 solid m3, and by household 6.5–6.6 solid m3. The average annual per caput expenditure on fuelwood was $ 9.7. This corresponds to a household of about 5 persons and means a household (family) expenditure of slightly less than $ 50 per annum, which is about 8% of the total household costs. Applying the Monrovia data to the whole of Liberia, it was estimated that fuelwood consumption in the whole country was 1.62 million m3 in 1965.

The PDF includes a summary in Finnish.

  • Roitto, ORCID ID:E-mail:
article id 7607, category Article
Eino Oinonen. (1969). The time table of vegetative spreading of the lily-of-the-valley (Convallaria majalis L.) and the wood small-reed (Calamagrostis epigeios (L.) Roth) in southern Finland. Acta Forestalia Fennica no. 97 article id 7607. https://doi.org/10.14214/aff.7607

The purpose of this study has been to compile a time-table for the vegetative spreading o the lily-of-the-valley and the wood small-reed. The diameters of the mainly solitary stands of these species have been compared to stand diameters of bracken (Lycopodium clavatum, L. annotium, and L. complanatum), to tree age determined by basal borings, and to times of fires in the site.

Regeneration of the lily-of-the-valley (Convallaria Majalis L.) and the wood small-reed (Calamagrostis epigeios (L.) Roth) from seed is relatively infrequent, and distance between stands may be considerable. Regeneration is more common after fire. The stands of the species are relatively fire resistant, especially on heathlands, where the subsurface parts are safe in the mineral soil. Large stands are generally due to vegetative spreading.

The rate of vegetative spreading of both of the species is practically constant, and about equal, 12.5 cm/year in diameter and 6.2 cm/year in the radial direction. When the actual regeneration time after the fire is not known, the rate of the spreading can be lower than this number.

  • Oinonen, ORCID ID:E-mail:
article id 7187, category Article
Eino Oinonen. (1968). Lycopodium clavatum L.- ja L. annotium L.-kasvustojen laajuus rinnastettuna samanpaikkaisiin L. complanatum L.- ja Pteridium aquilinum (L.) Kuhn -esiintymiin sekä puuston ikään ja paloaikoihin. Acta Forestalia Fennica no. 87 article id 7187. https://doi.org/10.14214/aff.7187
English title: The size of Lycopodium clavatum and L. Annotinum stands as compared to that of L. Complanatum and Pteridium aquilinum stands, the age of the stand and the dates of fire, on the site.

The present study is a part of larger project into the size and age of certain forest plants. This study seeks to confirm the size-age relationship of Lycopodium clavatum L. and L. annotium L. stands, and the time of sporal regeneration. The stand dimensions were plotted against the size of bracken (Pteridium aquilinum (L.) Kuhn) and ground pine (Lycopodium complanatum L.) stands growing on the same site, and against the age of the timber and the time of fire on the site.

The method based on parallel measurements carried out in burned forests has proved to be suitable for establishing the rate of spreading of stands and their age. The three club-moss species proved to be much alike in their sporal regeneration. They, as well as bracken, regenerate under the condition created by fire. The largest detached patches are often clones. Both Lycopodium clavatum and L. annotium survive fire poorly. Thus, the maximum size of the clones is usually connected with the last forest fire. Pieces of the shoots may survive the fires.

Sporal regeneration of these species also occur without the aid of fire. As also variation in the annual growth of the shoots can be considerable, the stand size of these species is not as good indicator of the date of fire as with Pteridium aquilinum and L. complanatum. The winding appearance of the shoots increases the error in determination of stand age by the stand size further.

The results emphasize the importance of taking into account the time and spread of the plants in the traditional vegetation analysis. A central question is: what is an individual.

The PDF includes a summary in English.

  • Oinonen, ORCID ID:E-mail:
article id 4728, category Article
Yrjö Roitto. (1965). Polttopuun käyttö Euroopassa vv. 1950.1960 sekä mahdollisuudet polttopuun teolliseen käyttöön v. 1975. Silva Fennica no. 117 article id 4728. https://doi.org/10.14214/sf.a14286
English title: Use of fuel wood in Europe in 1950-60 and possibilities of converting fuelwood to industrial uses by 1975.

According to the statistics, the fuel wood consumption in Europe has declined since 1925/1929, when the total fuel wood consumption was 144 million m3. In 1960 the consumption was 108 million m3. Because of insufficient statistics in the early years, the drop may even be larger than shown by the figures. The aim of this paper is to assess what part of European fuel wood removals in 1960 could be used for industrial purposes by 1975.

It was estimated that in 1975 the use of fuel wood in Europe will be about 45–55 million m3 less than in 1960 and about 10 million m3 of this amount will consist of coniferous species. It is believed that about 45 million m3 could be transferred to industrial use by 1975, and 55 million m3 is supposed to be the maximum reduction achievable by 1975. The estimates are based on the revised European fuel wood removal figures.

The new European timber trends and prospects study reveals a shortage of small-sized coniferous wood of about 25–43 million m3, depending on whether the exports from Europe are curtailed or not. The decrease of coniferous fuel wood of 10 million m3 could almost entirely be transferred for the use of industry.

A more important question is, is there demand for the extra small-size broadleaved wood. It is important to note that there is no longer any technical limitations on the use of this kind of wood for producing pulp, paper paperboard and wood-based panel products.

Fuelwood is often collected by the farmer and used near the farm. If the wood is to be used in the industry, harvesting and transport costs need to be decreased. However, productivity of the logging and transportation may be significantly improved by cutting the trees into longer lengths and professional harvesting. About 40% of the potential transfer of fuelwood to industrial uses is concentrated in Finland (7 million m3), France (5 million m3), and Italy (7 million m3). Other countries with significant potential shifts could be Romania, Spain and Yugoslavia.

The PDF includes a summary in French, German, Dutch, Russian and Finnish.

  • Roitto, ORCID ID:E-mail:
article id 4669, category Article
V. A. Kolehmainen. (1956). Vehkatallinmaa. Silva Fennica no. 90 article id 4669. https://doi.org/10.14214/sf.a9116
English title: Vehkatallinmaa, a successful reforestation area in Central Finland.

In 1933, forest fire caused by locomotive sparkle burned about 600 hectares of forest in a forest district named Vehkatallinmaa, in Central Finland. In 1934–36, the burned area was reforested, using different sowing and planting methods. At the same time, areas with poor runoff were drained. The results from reforestation throughout the area have been good. Also, natural regeneration of coniferous trees, especially Scots pine (Pinus sylvestris L.) has occurred. Even deciduous trees, especially birch (Betula sp.), have regenerated naturally in the area. The forests are an evidence of the adaptability of broadcast sowing on snow crust as a method of reproduction.

The PDF includes a summary in English.

  • Kolehmainen, ORCID ID:E-mail:
article id 4624, category Article
Polttoainekomitea. (1952). Polttoainekysymys vuonna 1951 : polttoainekomitean mietintö. Silva Fennica no. 74 article id 4624. https://doi.org/10.14214/sf.a9096
English title: The fuel question in Finland in 1951.

The government of Finland appointed a committee to make a suggestion of measures to be taken to arrange fuel supply during the heating season. The committee drafted also a plan to regulate and govern the fuel economy.

The committee estimated that the total consumption of coal, coke, firewood, waste wood and fuel peat, converted into pine firewood increased from 33.8 million eu.m in piled measure in heating period of 1952-53 to 42.9 million in 1955-56. According to the report, the demand of fuel is met increasingly through imported fuels, such as coal, coke and oil. The change is mainly due by their lower price and technically easy handling compared to domestic fuels.

The committee suggests that the production of domestic fuels, peat and firewood, should be increased and rationalized. In addition, financial support should be targeted to construct hydroelectric plants. Fuel peat industry should be developed further. The use of oil should be promoted, and boilers able to use different kinds of fuel should be constructed. To be prepared in changes in international situation, stocks of fuel are needed.

  • Polttoainekomitea, ORCID ID:E-mail:
article id 4581, category Article
V. Lihtonen. (1945). Metsäteollisuusyhtiöiden metsistä ja niiden hakkuista. Silva Fennica no. 61 article id 4581. https://doi.org/10.14214/sf.a9085
English title: Forests of woodworking industry and the fellings carried out in them.

The aim of this treatise is to describe forests owned by timber companies, their area and position, the quality of forests, the condition of the forests, and fellings carried out during the World War II.

Area of the company-owned forest was 1,95 million hectares, 1,64 million hectares of which was productive and 0,31 hectares inferior forest soil, not including the areas lost after the war. Most of the forests were situated in remote regions. Average volume of the tree stands was slightly larger than in farm-owned forests. Fellings counted for 84% of the growth of the forests.

During the war  the state set felling quotas for both company, private and state forests. It was widely discussed how well they were met by the different owner groups. According to the statistics, the companies had followed relatively closely their cutting plans in peace years. Cuttings were highest in 1939, when the war begun. In the war years 1940-43, lack of workforce, horses and cars for transport complicated logging. The fellings increased again during truce after Winter War. Especially demand for small timber increased during the war. Felling of firewood increased in all the owner groups, in particular in the private forests that were situated near settlements. in general fellings were higher in forests that were easiest to reach.

During the war the companies acquired timber more from their own forests. The fellings from company forests were in war years 70% of those in peace years. The article concludes that companies fulfilled the requirements as well as it was possible in the circumstances.

The article includes an abstract in English.

  • Lihtonen, ORCID ID:E-mail:
article id 4568, category Article
Atri S. Arimo. (1939). Paloalojen metsittämisestä. Silva Fennica no. 52 article id 4568. https://doi.org/10.14214/sf.a13975
English title: Forest regenration of burned areas.

Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes preparation and forest regeneration methods of a burned area.

  • Arimo, ORCID ID:E-mail:
article id 4524, category Article
Risto Sarvas. (1937). Havaintoja kasvillisuuden kehityksestä Pohjois-Suomen kuloalueilla. Silva Fennica no. 44 article id 4524. https://doi.org/10.14214/sf.a9069
English title: Observations on development of vegetation in burned areas in Northern Finland.

The aim of the study was to follow development of vegetation in dry upland forest sites after forest fire. The sample sites were situated in the counties of Muonio, Kolari, Sodankylä, Pelkosenniemi, Savukoski, Kemijärvi and Salla, in the northernmost Finland.
The growth of plant communities can arise either from the vegetation and seeds that survived the fire, or from seeds that spread from the surrounding areas. The development of vegetation in the burned areas was unexpectedly independent of the surrounding areas, which indicates that role of the seeds from the outside of the burned ares is small. The occurence of different species of lichens, moss, scale moss and vascular plants in the burned areas are described in detail. The development of vegetation was strongly dependent on the forest site type. The thin humus layer of Cladina site type burns usually evenly, and also the vegetation develops more evenly than in the more fresh site types. Vegetation typical for burned areas was fully developed within 10-15 years, and after 25 years it began to resemble the vegetation of Cladina site type forests. The ground vegetation of Calluna type burned area was more patchy. It developed quicker than in Cladina type. Absense of lichens made it seem more fertile than is usual for Calluna type. The humus layer of Empetrum-Myrtillus site type burned unevenly, and if the area was lightly burned, the vegetation recovered quickly. The vegetation was often patchy.
The PDF includes a summary in German.

  • Sarvas, ORCID ID:E-mail:
article id 4444, category Article
Toivo Wilhelm Paavonen. (1927). Forest fire insurance in Suomi. Silva Fennica no. 4 article id 4444. https://doi.org/10.14214/sf.a8392

Establishing an insurance company for insuring the private forests was suggested already in 1911 in Finland. In 1925 two companies, the Suomen Metsänomistajain Keskinäinen Metsäpaloapuyhdistys (The Forest Owners' Mutual Forest Fire Insurance Company) and the Keskinäinen Vakuutuslaitos Sampo (The Sampo Mutual Insurance Company), operated in forest fire insurance. They both had similar conditions, rates and principles for estimating losses caused by forest fire.

A total of 2,18 million hectares (16,4%) of the 13.3 million hectares of private forests in Finland were insured in 1925. Of the insured forests, 0.01–1.35% burned annually in 1916–1925. The insured forests were classified either small forests (size of the trees less than 18 cm in diameter), large forests or forests in general. The basic insurance compensated the stump value of the timber felled and lying in the forest up to 25% of the volume in the area. In case the fire decreases productivity of the land, the insurance covered the forest soil up to 50% of the value of the land. Larger losses could be compensated by paying an additional premium.

A summary in Finnish is included in the PDF.

  • Paavonen, ORCID ID:E-mail:
article id 4444, category Article
Toivo Wilhelm Paavonen. (1927). Forest fire insurance in Suomi. Silva Fennica no. 4 article id 4444. https://doi.org/10.14214/sf.a8392

Establishing an insurance company for insuring the private forests was suggested already in 1911 in Finland. In 1925 two companies, the Suomen Metsänomistajain Keskinäinen Metsäpaloapuyhdistys (The Forest Owners' Mutual Forest Fire Insurance Company) and the Keskinäinen Vakuutuslaitos Sampo (The Sampo Mutual Insurance Company), operated in forest fire insurance. They both had similar conditions, rates and principles for estimating losses caused by forest fire.

A total of 2,18 million hectares (16,4%) of the 13.3 million hectares of private forests in Finland were insured in 1925. Of the insured forests, 0.01–1.35% burned annually in 1916–1925. The insured forests were classified either small forests (size of the trees less than 18 cm in diameter), large forests or forests in general. The basic insurance compensated the stump value of the timber felled and lying in the forest up to 25% of the volume in the area. In case the fire decreases productivity of the land, the insurance covered the forest soil up to 50% of the value of the land. Larger losses could be compensated by paying an additional premium.

A summary in Finnish is included in the PDF.

  • Paavonen, ORCID ID:E-mail:

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