The forest structure in the present pine dominated landscapes was controlled by the fire frequency. In eastern North Karelia, for example, the sandy soils presently covered by xeric pine forests may have been earlier mixed pine-spruce forests. This situation prevailed as long as the fire interval was long enough, say about 200 years or more, to the understory spruce stands to be developed. This promoted strong canopy fires that totally renewed the stands, and so started a classical succession cycle of the forest composition that in more fertile soils led to spruce dominance. Our data indicate that such wildfires spread often several kilometres over the wide wetlands of the present Patvinsuo National Park, and so indicate severe drought periods during their occurrences. When the fires during the time of swidden agriculture repeated at shorter average interval, about 50 years or less, they were milder surface fires that left most pines alive, but destroyed spruce. This change in the fire interval decisively controlled the forest structure in Finland as seen all over the country in the replacement of the strong predominance of spruce with that of pine, birch and/or even (grey) alder as indicated by pollen data and historical records.
Spruce forests have a different history of fire regime than have pine forests.
We studied that question at Ulvinsalo strict nature reserve in Kuhmo, eastern Finland. The area belongs to middle boreal zone and is a mosaic of old spruce dominated forests on morainic soil (drumlins) and of long, narrow mire basins and of a few small lakes. We concentated the corings to several very small mire basins ( 0.06-0.6 ha in area) situated in shallow depressions inside the forests, and carefully studied the in situ fire history of the mire basins, and local fire history of the surrounding forests. We based our study on visible charcoal layers in the peat profiles (eight sites) and in addition on microscopical examination of the occurence of macroscopic charcoal fragments in small peat samples taken continuously throughout the stratigraphy (performed at two sites). Charcoal layer stratigraphy was analyzed from several replicate cores at each site.
The upland (mineral soil) forest of Hylocomium - Vaccinium type (HMT) spruce forests surrounding the basins had been burning with the average intervals as follows:
1. before 7000 B.C. 300 - 400 years 2. durting the Atlantic Cronozone (about 7000 - 4000 B.C.) about years 3. during the abiegnic time (since about 4000 B.C.), 320 - 520 years At one of study sites, absence of charcoal particles suggested a possible period of 2700 years during the abiegnic time without any local forest fire, and there were several periods of about 200 - 600 years without any fire in the forest surrounding the mire basin.
Two of our mire basins indicated no in situ fires during the whole Holocene era, although the other basins had on average burned over once during a period of about 500-1000 years. According to the fire scar studies in the same Ulvinsalo area (Haapanen and Siitonen 1978) the fire interval between the early 18th century and early 20th century was in average about 100 years. During that period slash-and-burn cultivation was practised in the area, and one can still find some remains of the past human activities there.
Most of the forest fires in wilderness are naturally ignited by lightning. The lightining-ignited forest fire density is estimated for time period 1985-1992 and 1996-2001 to be 0.01 - 0.1 ignition per year per km-2 in the Middle Boreal vegetation zone of Finland, whilst the corresponding figures are 0.01 – 1.1 for the municipalities belonging to the southern boreal zone in Finland. Larjavaara et al. (2003) estimated the lightning ignition probability to be about 10 times higher in the southernmost parts of Finland than in northern parts.
For the period 1981-191 those figures are estimated in the Russian Karelia to be at 0.04 ignition yr -1 per 10 000 ha (Sannikov and Goldammer, 1996), and in Sweden, between 0.03 and 0.23 ignition yr--1 10 000 ha-1 during period 1944 - (Granstrm 1993). One may apply these figures for the "forest isles" separated by wetlands and lakes in Ulvinsalo area. Assuming that each dry land patch burned separately, because the fires were blocked at the edges of the mires (and lakes), one can estimate that for example in a continuous area of dry soil of about 100 hectares, the above mentioned value for Russian Karelia would result in an average fire interval of more than 1000 years. But since most stretches of dry land in Ulvinsalo are only some ten hectares of size, they would have burned much less frequently, even if a higher lightning ignition density value (e.g. above Swedish estimate) is applied.
These results from Ulvinsalo can be generalized to similar middle boreal coniferous forests in mosaic like landscapes, that in fact are very common in many areas in Fennoscandia and northwestern Russia. It is possible that fire was much more frequent in other areas with less fragmented landscapes and with milder climate. Fires had been rare also in the natural spruce dominated landscape of the Paanajrvi wilderness (Russia), in northeastern Fennoscandia (Wallenius et al., 2005). Similarly, the old spruce forests of the Onega peninsula, Russia, studied by Wallenius (2002) indicate no traces of fires in 35 % of the study sites. In remote part of the Komi Republic, Russia, the old climax forests of the spruce dominated type studied by Syrjnen at al. (1994) are usually without any apparent sign of wildfires, as well. So, the often emphasized importance of fire as the main disturbance factor in natural forests can not be applied for all contemperanous spruce dominated landscapes. Our new results arouse serious concern about the the present forestry practice in coniferous forests in which intensive forestry has strongly distorted the rotation time from that of the natural state.
References Goldammer, J.G. & Furyaev, V.V. 1996: Fire in ecosystems of boreal Eurasia.
In, Goldmmer, J.G., Furyaev, V.V. (eds), Fire in Ecosystems of Boreal Eurasia.
Kuwer Acad. Publ. Dortrecht, pp. 1 - 20.
Granstrm, A., 1993: Spatial and temporal variation in lightning ignition in Sweden. J. Veg. Sci. 4, 737 - 744.
Haapanen A., & Siitonen, P. 1978: Kulojen esiintyminen Ulvinsalon luonnonpuistossa. (Forest fires in Ulvislo strict natre reserve). Silva Fennica 12, 187 - 200.
Huntley, B. 1988: Glacial and Holocene vegetation history of Europe. In, Huntely, B.
& Webb III, T. (eds) Vgetation History, 341 - 303. Kluwer Acad. Publ., Dordrecht.
Larjavaara, M., Kuuluvainen, T., & Rita, H. 2005: Spatial distribution of lightning-ignited forest fires in Finland. Forest Ecology and Management 208, 177-188.
Lehtonen, H. 1988: Fire history recorded on pine trunks and stumps: influence of land use and fires on forest structure in North Karelia. Scandinavian Journal of Foret Research 13, 462 - 468.
Lehtonen, H. & Kolstrm, T. 2000. Forest fire history in Vienna Karelia, Russia. Scand. J. For. Res.15, 585 - 590.
Pitknen, A., Tolonen, K. & Jungner, H. 2001: A basin-based approch to the long-term history of forest fires as determined from peat strata. The Holocene 11, 594 - 605.
Pitknen, A., Huttunen, P., Jungner, H. and Tolonen, K. 2002: A 10 000 year local fire history in a dry heath forest site in eastern Finland, reconstructed from charcoal layer records of a small mire. Can. J. For. Res. 32, 1875 - 1880.
Pitknen, A., Huttunen, P., Jungner, H., Merilinen, J. & Tolonen, K. 2003:
Holocene fire history of middle boreal pine forest sites in eastern Finland.
Ann. Bot. Fennici 40, 15.
Sannikov, S.N. & Goldammer, J.G. 1996: Fire ecology of pien forests of northern Eurasia. In, Goldammer, J.G. & Furyaev, V.V. (eds), Fire in ecosystems of boreal Eurasia. Kuwer, Dordrecht, pp. Syrjnen, K., Kalliola, R., Puolasmaa, A. & Mattson, J. 1994: Landscape structure and forest dynamics in subcontinental Russian European taiga. Ann.
Zool. Fennici 31, 19 - 34.
Tolonen, K. 1983: The post-galacial fire record. In, Wein, R.W. & MacLean, D.A. (eds), The role of fire in northern circumpolar ecosystems. Scope 18, 21 - 44. Wileys, New York.
Tolonen, M. 1978: Palaeoecology of annually laminated sediments in Lake Ahvenainen, S. Sinland. I. Pollen and charcoal analyses andb their relation to human impact. Ann. Bot. Fennici 15, 177 - 208.
Vakurow, A.D. 1975. Forest fires in the north. Izdatjelsvo Nauka Laboratorija Lesovedenija Moscow (In Russian). 98 pp.
Wallenius, T. 2002: Firest age distribution and traces of pastv fires in a natural boreal landscape dominated by Picea abies. Silva Fennica 36(1), 201 - 211.
Wallenius, T. H., Pitknen, A., Kuuluvainen, T., Pennanen, J. & Karttunen, H.
2003: Fire history and forest age distribution of an undamaged Picea abies dominatwed landscape. Can. J. For. Res. 35, 1 - 13.
Zackrisson, O. 1977: Influence of forest fires on the north Swedish boreal forest. Oikos 29, 22 - 32.
THE USE OF PEATLANDS IN FINLAND WITH A SPECIAL EMPHASIS ON RESTORATION H. VASANDER Department of Forest Ecology, University of Helsinki, Harri.Vasander@helsinki.fi Introduction Finnish people have always had a strong connection with peatlands. The Finnish word for Finland, Suomi, is associated with the word suo, meaning peatland. A Swedish poet and researcher, Georg Stierhielm (1598-1672), was probably the first one to connect Suomi and suo. The inhabitants living on lowlying areas with a lot of mires would have given themselves or be given by their neighbours the name Soo-ma (land of mires, suomaa in Finnish). The inhabitants would have been called as Soo-mehe (men or people of the mires, suomiehet in Finnish).
Stierhielm also speculated about the origin of the word “Finland”.
According to his first theory the word “fin” would originate from a Swedish word fin meaning beautiful. But according to his second theory it could originate from a Swedish word fiende, meaning an enemy, too. Maybe the best explanation would be that “Finland” could be connected to the English word “fen”, describing a special kind of treeless mire (Laaksonen 1995).
Nowadays prevails the theory of Koivulehto (1993) that the word Suomi is based on an old Baltic word meaning lowland. The same word could have given the origin also for the words Hme and Saame, meaning areas in southern Finland and Lapland. Probably also the Russian word zemlja, meaning land, could be traced to this old Baltic word. So Finnish people could be described as inhabitants of lowlands - with a dominance of mires. In the first century, the Greek historian, Tacitus, mentioned a northern tribe, the fenns, who hunted in the big northern swampy lowlands. The Finnish word suo is a very old one having tens of synonyms for different kind of mires in different dialects of the Finnish language.
The dominance of mires and their importance for local people in many ways could be explanation that our ancestors have been able to survive in these harsh northern conditions. In the past, wild reindeer and moose were pursued onto mires during late winter when the snow was hard enough to carry a hunter on his skis but not the heavy animals. In spring, mires were important for the hunting of migratory birds and bird eggs were collected to prevent starving (Korhonen & Vasander 1996).
In this review, I first describe shortly the use of mires in Finland. There is a clear trend that new ways to utilise peatlands are invented while the proportion of old ways of utilisation may remain with a changed intensity. Specifically, I then concentrate more on the restoration of peatlands drained for forestry. This last way of utilisation is quite recent in Finland and is done to promote biodiversity of plants, animals and mire sceneries. Also, restored buffer zones between forestry land and waterways could be used in peatland forestry to mitigate the harmful effects caused by liberated nutrients on the recipient ecosystems.
The use of peatlands for agriculture.
Agricultural use of peatlands started in the Stone-Age with the haymaking on sedge-dominated mires by lake and river shores. The earliest written accounts on agricultural use of peatlands are from the late 17th century.
Then the vicar of Isokyr (Ostrobothnia), Elias Brenner, described the successful peatland cultivation carried out by his father. The cultivation method started by ditching of the peatland, after that the dry surface was burnt, worked over, and fertilized for the sowing of rye. This cultivation method later spread from Ostrobothnia to other regions, including Savolax and Karelia (Lappalainen 1996).
The foundation of the Finnish Society of Peat Cultivation in 1894 was significant for the development of the use of peatlands. The Society published its first yearbook in 1897, and through its work many Finnish esteemed scientists became very influential in Finland, for example Mauno J. Kotilainen, Erkki Kivinen, and Yrj Pessi (Lappalainen 1996).
It has been estimated that a total of 0.7 – 1.0 million hectares of peat soils have been cleared for agriculture in Finland. However, most of them were used for a relatively short period only, and a large proportion has become mull or mineral soils. At the peak, peat soils comprised one third of Finland’s cultivated field area. The need for new fields was greatest when the population started to increase more than 100 years ago, and after the Second World War when new arable land was needed to compensate for the land lost during the war (Myllys 1996).
According to the latest inventory of the cultivated organic soils in Finland, the area of organic soils with the organic matter content more than 40% (i.e. peat) was 85 000 ha (3,8% of the arable land). The area of organic soils with the organic matter content of 20 – 39,9% and often with a mineral subsoil, was 214 000 ha (9,7% of the arable land).
Altogether, the area of these soils was 300 000 ha which is 13.6% of the arable area in Finland (Myllys & Sinkkonen 2004). It is important to know the areas of organic arable soils as the leaching of nutrients (especially N and P) to watercourses (Huhta & Jaakkola 1993) and greenhouse gas emissions (CO2, N2O) (Martikainen et al. 2002) are bigger than those from the mineral soils.
The use of peat for energy and horticulture.
Peat was first used for energy in Finland by the metal industry in 1876. World wars have been a stimulus for some small increase in the use of domestic fuels including peat. After the Second World War energy peat harvesting gradually increased in Finland till 1952. As international trade started again with an increase in the import of fossil fuels, the sales of domestic biofuels started to decrease. Decline in the demand for indigenous fuels was especially steep in the 1960s, when cheap oil flowed into the country. This development nearly led to a total termination of the energy peat production and use (Sopo & Aalto 1996).
The use of peat for energy increased after the oil crisis in 1970s.
Already in 1974 the Second Peat Development Program was approved by the Finnish Government. The aim of this program was to expand the annual fuel peat supply to 20 million m3. The target was achieved for the first time in 1986. Depending on the summer weather the peat supply has varied between 5 – 30 million m3 in a year. The area used for harvesting is 50 000 – 60 000 ha in a year. Totally peat companies have 120 000 ha of peatlands at their disposal which would be enough to guarantee constant peat supply almost until the middle of this century. The share of peat has been approximately 6% of the annual energy consumption of Finland (Sopo & Aalto 1996).
The use of peat moss (Sphagnum peat) became prevalent in the 1960s and 1970s especially for growing tomatoes and cucumbers.
Generalization of inactive substrates in the 1980s led, however, to a dramatic decrease in the use of moss peat but today there seems to be a comeback in the use of peat as growing medium. Growing bags and growing boards are the latest innovations in this field. All nutrients are given in the fertilizer solution instead of the previous NK fertilization since usually only lime is applied to the substrate instead of the previous basic fertilization. As a result of research and development in Finland it has been possible to develop products from peat that give the substrate a strong structure and enable long-term cultivation and abundant irrigation.
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