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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'forest fire'.

Category: Research article

article id 10334, category Research article
Annija Kārkliņa, Guntis Brūmelis, Iluta Dauškane, Didzis Elferts, Lāsma Freimane, Māra Kitenberga, Zane Lībiete, Roberts Matisons, Āris Jansons. (2020). Effect of salvage-logging on post-fire tree establishment and ground cover vegetation in semi-natural hemiboreal forests. Silva Fennica vol. 54 no. 5 article id 10334.
Highlights: Effect of salvage logging on post-fire understory vegetation was assessed; Effect of salvage logging differed depending on forest types; In dry-poor stands, Calluna vulgaris was hindering other plant species; In wet stands, logging had positive effect on understory vegetation diversity; Salvage logging enhanced the effect of natural disturbance in dry-rich stands.

Fire is a common disturbance in boreal forests causing changes in biological diversity at various spatial scales. In the past 100 years, forest management has limited fire outbreaks, but in the future, the fire-affected forest area is expected to increase in many regions due to climate change. Burned forests are typically salvage-logged, but the effect of this type of management versus natural regeneration on biological diversity is not well understood, particularly the mid-term effect to tree establishment and understory vegetation composition and diversity. Various management methods were used after a large fire in 1992 in a peatland-forest complex and neighbouring managed forests, which created an experimental setup for study of the effect of management after fire in the Sliteres National park, northwestern Latvia. Understory vegetation was described in plots using a design of four forest and three management types: natural regeneration (unmanaged) and managed sites with salvage logging followed by no further human intervention and salvage logging with planting. Post-fire management had different effect in each forest type. Species richness was higher in forest types with salvage logging than in natural regenerated sites on rich wet and rich dry forest types, but not for the poor forest types. Tree regeneration was generally greater in salvage-logged stands, but differed between forest types. Species composition was related to tree regeneration and canopy openness. In contrast to other studies, salvage logging had a positive mid-term effect to ground vegetation diversity and tree establishment in the studied stands, implying potential for concomitant management and conservation of ground cover vegetation in semi-natural stands.

  • Kārkliņa, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail: (email)
  • Brūmelis, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia ORCID ID:E-mail:
  • Dauškane, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia ORCID ID:E-mail:
  • Elferts, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia ORCID ID:E-mail:
  • Freimane, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail:
  • Kitenberga, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail:
  • Lībiete, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail:
  • Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail:
  • Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia ORCID ID:E-mail:
article id 10084, category Research article
Mihails Čugunovs, Eeva-Stiina Tuittila, Jari Kouki. (2020). Proximity to charred logs in burned forests likely affects decomposition processes in the soil. Silva Fennica vol. 54 no. 1 article id 10084.
Highlights: Standardised organic substrate decomposition was tentatively observed to be faster adjacent to non-charred downed logs than away from the logs or adjacent to charred logs; A spatial linkage was observed between non-charred logs and decomposition in the soil in burned boreal forests; Proximity to a charred log may provide a micro-environment where decomposition rates differ from the surrounding forest soil.

We studied the spatial decomposition rates of standardised organic substrates in soils (burned boreal pine-dominated sub-xeric forests in eastern Finland), with respect to charred and non-charred coarse woody debris (CWD). Decomposition rates of rooibos plant litter inside teabags (C:N = 42.870 ± 1.841) and pressed-sheet Nordic hardwood pulp (consisting of mainly alpha-cellulose) were measured at 0.2 m distance from 20 charred (LC0.2) and 40 non-charred logs (LNC0.2). We also measured decomposition at 60 plots located 3–10 m away from downed logs (L3,10). The rooibos decomposition rate constant ‘k’ was 8.4% greater at the LNC0.2 logs than at the L3,10 or LC0.2 logs. Cellulose decomposed more completely in 1 micron mesh bags at LNC0.2 (44% of buried bags had leftover material) than at LC0.2 (76%) or L3,10 (70%). Decomposition of cellulose material was rapid but varied greatly between sampling plots. Our results indicate that decomposition of the standardised organic matter was more rapid close to CWD pieces than further away. However, only the plots located near non-charred logs (LNC0.2) exhibited high decomposition rates, with no corresponding increase observed at the charred logs (LC0.2). This suggests a possible noteworthy indirect effect of forest burning on soil organic matter (SOM) decomposition rates close to charred CWD after forest fires. We urge for more studies on this tentative observation as it may affect the estimates on how fires affect carbon cycling in forests.

  • Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: (email)
  • Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: E-mail:
  • Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: E-mail:
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.
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: (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:
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.
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: (email)
  • Kneeshaw, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, 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.
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: (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 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.
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: (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.
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: (email)
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.
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: 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.
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.

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.
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.
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 7337, category Article
Erkki K. Kalela. (1937). Vakuutetuissa metsissä vuosina 1925-34 sattuneista kuloista. Acta Forestalia Fennica vol. 46 no. 2 article id 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.
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.
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.

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.

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.

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 5521, category Article
Taneli Kolström, Seppo Kellomäki. (1993). Tree survival in wildfires. Silva Fennica vol. 27 no. 4 article id 5521.

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 5002, category Article
Antti Haapanen, Pertti Siitonen. (1978). Kulojen esiintyminen Ulvinsalon luonnonpuistossa. Silva Fennica vol. 12 no. 3 article id 5002.
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.
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 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.

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.

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 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.

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.
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 4669, category Article
V. A. Kolehmainen. (1956). Vehkatallinmaa. Silva Fennica no. 90 article id 4669.
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 4568, category Article
Atri S. Arimo. (1939). Paloalojen metsittämisestä. Silva Fennica no. 52 article id 4568.
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.
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.

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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