Articles containing the keyword 'fire'

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, E-mail: pp@mm.unknown
• Haila, E-mail: yh@mm.unknown

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, E-mail: rp@mm.unknown
• Kotiranta, E-mail: hk@mm.unknown

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, E-mail: jp@mm.unknown

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, E-mail: vg@mm.unknown
• Bakkal, E-mail: ib@mm.unknown

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, E-mail: vg@mm.unknown
• Bakkal, E-mail: ib@mm.unknown
• Stavrova, E-mail: ns@mm.unknown

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, E-mail: tk@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown

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, E-mail: hv@mm.unknown
• Lindholm, E-mail: tl@mm.unknown

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, E-mail: ah@mm.unknown
• Siitonen, E-mail: ps@mm.unknown

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, E-mail: yr@mm.unknown

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, E-mail: vh@mm.unknown

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, E-mail: vk@mm.unknown

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, E-mail: –

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, E-mail: vl@mm.unknown

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, E-mail: aa@mm.unknown

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, E-mail: rs@mm.unknown

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, E-mail: tp@mm.unknown

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, E-mail: eo@mm.unknown

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, E-mail: eo@mm.unknown

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, E-mail: mf@mm.unknown

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, E-mail: pe@mm.unknown

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, E-mail: pm@mm.unknown

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, E-mail: vp@mm.unknown

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, E-mail: vh@mm.unknown

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, E-mail: vh@mm.unknown

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, E-mail: ek@mm.unknown

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 8^th or 10^th 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, E-mail: rs@mm.unknown

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, E-mail: jk@mm.unknown

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, E-mail: ar@mm.unknown

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.

• Heikinheimo, E-mail: oh@mm.unknown

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, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown

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, E-mail: at@mm.unknown
• Luukkanen, E-mail: ol@mm.unknown
• Bhumibhamon, E-mail: sb@mm.unknown

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, E-mail: yr@mm.unknown

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, E-mail: eo@mm.unknown

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, E-mail: eo@mm.unknown

Forest fires pose a significant threat to forest carbon storage and sinks, yet they also play a crucial role in the natural dynamics of boreal forests. Accurate quantification of biomass changes resulting from forest fires is essential for damage assessment and controlled burning evaluation. This study utilized terrestrial laser scanning (TLS) to quantify changes in ground vegetation resulting from low-intensity surface fires. TLS data were collected before and after controlled burnings at eight one-hectare test sites in Scots pine (Pinus sylvestris L.) dominated boreal forests in Finland. A surface differencing-based method was developed to identify areas exposed to fire. Validation, based on visual interpretation of 1 × 1 m surface patches (n = 320), showed a recall, precision, and F1-score of 0.9 for the accuracy of identifying burned surfaces. The developed method allowed the assessment of the magnitude of fire-induced vegetation changes within the test sites. The proportions of burned 1 × 1 m areas within the test sites varied between 51–96%. Total volumetric change in ground vegetation was on average –1200 m³ ha^-1, with burning reducing the vegetation volume by 1700 m³ ha^-1 and vegetation growth increasing it by 500 m³ ha^-1. Substantial variations in the volumetric changes within and between the test sites were detected, highlighting the complex dynamics of surface fires, and emphasizing the importance of having observations from multiple sites. This study demonstrates that bitemporal TLS measurements provide a robust means for characterizing fire-induced changes, facilitating the assessment of the impact of surface fires on forest ecosystems.

• Tienaho, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0002-6574-5797 E-mail: noora.tienaho@uef.fi
• Saarinen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-2730-8892 E-mail: ninni.saarinen@uef.fi
• Yrttimaa, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-2648-523X E-mail: tuomas.yrttimaa@uef.fi
• Kankare, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0001-6038-1579 E-mail: ville.kankare@uef.fi
• Vastaranta, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0001-6552-9122 E-mail: mikko.vastaranta@uef.fi

• Wallius, European Forest Institute, Yliopistokatu 6 B, FI-80100, Joensuu, Finland; Jyväskylä University School of Business and Economics, P.O. Box 35, FI-40014 University of Jyväskylä, Finland https://orcid.org/0000-0003-2576-9994 E-mail: venla.j.wallius@jyu.fi
• Kunttu, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0002-7298-3363 E-mail: janni.kunttu@helsinki.fi
• Hurmekoski, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0001-8717-7287 E-mail: elias.hurmekoski@helsinki.fi
• Hujala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-7905-7602 E-mail: teppo.hujala@uef.fi
• Nyrud, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: anders.qvale.nyrud@nmbu.no
• Hoen, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: hans.hoen@nmbu.no

Forests in the western United States generally have increased in tree density since Euro-American settlement, particularly through increases in fire-sensitive species, such as spruces, firs, and junipers. Like most areas, the Black Hills region in western South Dakota and eastern Wyoming was logged for forest products and underwent agricultural conversion before historical forests were documented. To supplement historical reconstructions and accounts, we compared tree composition and densities (diameters ≥12.7 cm at 1.37 m above ground height) from historical General Land Office (GLO) records (years 1878 to 1915) and current Forest Inventory and Analysis (FIA) tree surveys (years 2011 to 2016) in the Black Hills Highlands of South Dakota. For composition, ponderosa pine (Pinus ponderosa P. Lawson & C. Lawson) decreased from 95% to 86% of all trees, with a consequent increase specifically of white spruce (Picea glauca (Moench) Voss) from 1.5% to 6.7% of all trees. Ponderosa pine currently is smaller in mean diameter by 7.4 cm, while white spruce is larger in mean diameter by 2.4 cm than historically. When the 35% of historical survey points without recorded trees were excluded, historical tree densities indicated an overall forested structure of savannas and open woodlands with tree densities ranging from 66 trees ha^–1 to 162 trees ha^–1. However, historical forests of the Black Hills incorporated dense stands. Tree densities have increased two- to more than four-fold, to 311 trees ha^–1 currently. These comparisons provide another source of information, paralleling changes documented in surface fire-dependent pine and oak forests throughout the United States, of transitions in forest composition and structure since Euro-American settlement.

• Tatina, Department of Biological Sciences, Dakota Wesleyan University, Mitchell, SD 57301 USA E-mail: rotatina@dwu.edu
• Hanberry, USDA Forest Service, Rocky Mountain Research Station, Rapid City, SD 57702 USA E-mail: brice.hanberry@usda.gov

Since fire frequency is expected to increase globally due to climate change, it is important to understand its effects on forest ecosystems. We studied the long-term patterns in species diversity, cover and composition of vascular plants and bryophytes after forest fire and the site-related factors behind them. Research was carried out in northwestern Estonia, using a chronosequence of Scots pine (Pinus sylvestris L.) stands, located on nutrient poor sandy soils, where fires had occurred 12, 23, 38, 69, 80 and 183 years ago. In every stand three 100 m² vegetation plots were established to collect floristic and environmental information. The effects on floristic characteristics of time since fire, light, and soil variables were evaluated with linear mixed models, followed by backward variable selection. Compositional variation was analysed with non-metric multidimensional scaling, Multi-response Permutation Procedures, and Indicator Species Analysis. Altogether, 31 vascular plant and 39 bryophyte species were found in vegetation plots. The cover of the vascular plant and bryophyte layers increased with a longer time since fire. Soil and light variables impacted the richness of several vascular plant and bryophyte groups, whereas only the richness of liverworts and dwarf-shrubs correlated with time since fire. Considerable compositional differences were observed in vascular plant and bryophyte assemblages between recently vs. long-time ago burned stands. To conclude, time since fire significantly impacted compositional patterns of vascular plants and bryophytes in pine forests on nutrient poor soils, although time-related trends in species richness were less evident.

• Orumaa, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: argo.orumaa@emu.ee
• Köster, Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111 (Yliopistokatu 7), 80130, Joensuu, Finland E-mail: kajar.koster@helsinki.fi
• Tullus, Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, Tartu, 51003, Estonia E-mail: arvo.tullus@ut.ee
• Tullus, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: tea.tullus@emu.ee
• Metslaid, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: marek.metslaid@emu.ee

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 E-mail: annija.karklina@silava.lv
• Brūmelis, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia E-mail: guntis.brumelis@lu.lv
• Dauškane, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia E-mail: iluta.dauskane@lu.lv
• 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 E-mail: didzis.elferts@lu.lv
• Freimane, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: lasma.freimane@silava.lv
• Kitenberga, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: mara.kitenberga@silava.lv
• Lībiete, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: zane.libiete@silava.lv
• Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: robism@inbox.lv
• Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: aris.jansons@silava.lv

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 E-mail: mihails.cugunovs@gmail.com
• Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
• Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

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 E-mail: janis.donis@silava.lv
• Kitenberga, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: mara.kitenberga@gmail.com
• Šņepsts, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: guntars.snepsts@silava.lv
• Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
• Zariņš, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: juris.zarins@silava.lv
• Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv

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 E-mail: mihails.cugunovs@uef.fi
• Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland 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 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 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 http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

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 E-mail: mareike.wieczorek@awi.de
• Kolmogorov, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia 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 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 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 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 E-mail: yktnan@rambler.ru
• Heinrich, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany E-mail: heinrich@gfz-potsdam.de
• Pestryakova, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia 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 E-mail: Ulrike.Herzschuh@awi.de

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 E-mail: mihails.cugunovs@uef.fi
• Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland 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 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 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 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 http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

• 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 E-mail: Olli-Pekka.Tikkanen@uef.fi
• 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 E-mail: irina.chernyakova@onego.ru

• Dragotescu, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada E-mail: idragot@hotmail.com
• Kneeshaw, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada E-mail: ddk@nn.ca

• de Mello, Federal University of Sergipe, Brazil E-mail: aadm@nn.br
• Nutto, Federal University of Paraná, Brazil E-mail: lnutto.ufpr@gmail.com
• Weber, Federal University of Paraná E-mail: ksw@nn.br
• Sanquetta, Carlos Eduardo Sanquetta E-mail: ces@nn.br
• Monteiro de Matos, Jorge Luis Monteiro de Matos E-mail: jlmdm@nn.br
• Becker, University of Freiburg, Institute of Forest Utilization and Work Science, Germany E-mail: gb@nn.de

• Bélisle, Centre for Forest Research, Université du Québec à Montréal, Montréal, Québec, Canada E-mail: annieclaude_b@hotmail.com
• Gauthier, Laurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, Sainte-Foy, Québec, Canada E-mail: sg@nn.ca
• Cyr, Institut Québécois d’Aménagement de la Fort Feuillue, Université du Québec en Outaouais, Ripon, Québec, Canada E-mail: dc@nn.ca
• 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 E-mail: yb@nn.ca
• Morin, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada E-mail: hm@nn.can

• Marques, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: smarques@isa.utl.pt
• Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jgg@nn.pt
• Borges, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jgb@nn.pt
• Botequim, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: bb@nn.pt
• Oliveira, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: mmo@nn.pt
• Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jt@nn.pt
• Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: mt@nn.pt

• 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 E-mail: jeovannalowe@gmail.com
• 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 E-mail: dp@nn.ca
• Savard, Wildlife Research, Science and Technology, Québec Region, 1141 Route de l’Église, P.O. Box 10100, Québec, Québec, G1V 4H5, Canada E-mail: jpls@nn.ca
• 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 E-mail: gr@nn.ca
• 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 E-mail: mb@nn.ca

• Hellberg, Tunstigen 10, SE-831 43 Östersund, Sweden E-mail: eh@nn.se
• Josefsson, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: torbjorn.josefsson@svek.slu.se
• Östlund, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: lo@nn.se

• Larjavaara, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: markku.larjavaara@helsinki.fi
• Kuuluvainen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: tk@nn.fi
• Tanskanen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: ht@nn.fi
• Venäläinen, University of Helsinki, Dept of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: av@nn.fi

• Pennanen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: juho.pennanen@helsinki.fi

• Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 56, FIN-00014 University of Helsinki, Finland E-mail: tuomo.wallenius@helsinki.fi

• Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi
• Mäki, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: jm@nn.fi
• Karjalainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: lk@nn.fi
• Lehtonen, Faculty of Forestry, University of Joensuu, P.O. Box 24, FIN-80101 Joensuu, Finland E-mail: hl@nn.fi

• Linder, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pl@nn.se
• Jonsson, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pj@nn.se
• Niklasson, Southern Swedish Forest Research Centre, SLU, Box 49, S-230 53 Alnarp, Sweden E-mail: mn@nn.se

• White, Canadian Forest Service, Pacific Forestry Centre, Natural Resources Canada, 506 West Burnside Road, Victoria, B.C., V8Z 1M5, Canada https://orcid.org/0000-0003-4674-0373 E-mail: joanne.white@nrcan-rncan.gc.ca

• Wallenius, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: tuomo.wallenius@metla.fi

• Dahlberg, Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden E-mail: anders.dahlberg@artdata.slu.se

• Gromtsev, Forest Research Institute, Karelian Research Centre of the Russian Academy of Sciences, P.O. Box 185610, Petrozavodsk, Pushkin st. 11, Russia E-mail: gromtsev@karelia.ru

• Ryan, USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, P.O. Box 8089, Missoula, Montana 59807, USA E-mail: kryan@fs.fed.us

• Päätalo, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: mlp@nn.fi

In boreal forests fires often ignite and spread within the dominant moss and lichen cover of the ground layer vegetation, which thus greatly influences fire hazard. We used an experimental set-up in greenhouse conditions to study the differences in how (1) fuel moisture and (2) wind velocity influence the ignition probability and fuel consumption among four common circumboreal ground vegetation fuels, Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens Schimp., Dicranum spp. and Cladonia rangiferina (L.) F. H. Wigg. Our results show that the reindeer lichen C. rangiferina was clearly the most flammable species, with high ignition probability even at high moisture contents and low wind velocities. Of the mosses, Dicranum was the least flammable, with low ignition probability and mass loss at low wind velocities regardless of moisture content. P. schreberi and H. splendens behaved somewhat similarly with wind velocities quickly increasing the initially low ignition probability and mass loss observed in the absence of wind. However, especially for mass loss, among-species differences tended to disappear with stronger winds. The observed differences can be explained by the different structures and growth forms of the studied species and open a potential avenue for improving forest fire risk predictions.

• Lindberg, Häme University of Applied Sciences, School of Bioeconomy, Visamäentie 35 A, P.O. Box 230, FI-13100 Hämeenlinna, Finland https://orcid.org/0000-0001-9045-2673 E-mail: henrik.lindberg@hamk.fi
• Aakala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@uef.fi
• Vanha-Majamaa, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: ilkka.vanha-majamaa@luke.fi

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 E-mail: mara.kitenberga@gmail.com
• Matisons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
• Jansons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
• Donis, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: janis.donis@silava.lv

• Kauhanen, Finnish Forest Research Institute, Kolari Research Station, Muoniontie 21 A, FIN-95900 Kolari, Finland E-mail: heikki.kauhanen@metla.fi