Forest Fires and EnvironmentalManagement in Norway
(IFFN No. 18 – January 1998, p. 72-74)
A report concerning forest fire as an ecological disturbance factor, with comments on the Norwegian fire regime, is now complete. The Norwegian fire regime is determined by its ignition sources, distribution of fuel, topography and climatic conditions.
Norway constitutes the Atlantic coast of the enormous Eurasian continent. Though the length-axis represents a distance of more than 1700 km from north to south, the country is very narrow. The terrestrial ecosystems of Norway are therefore among the most oceanicly influenced on the whole continent. The topography is very rugged with great variation on both regional and local scales. Considerable differences in precipitation and climatic conditions over short distances create the ecological basis for large regional differences in vegetation and fauna. Boreal coniferous forests stretch in from the east towards the Scandinavian mountain range and its alpine ecosystems. The coastal area has been classified as a boreonemoral zone characterized by temperate coastal forests. In the south, there are smaller areas in a nemoral zone which today are strongly influenced by human activity.
The fire pattern in a region associated with natural ignition sources is traditionally referred to as a “natural fire regime”. In Norway, this will mean fires ignited by lightning.
Coniferous tree species and understorey vegetation, together with humus and litter on the forest floor, constitute the best fuel. Vegetation and organic soil conditions are therefore important in determining where the majority of natural fires can occur in Norway. The natural fire regime closely follows climate. Heavy precipitation is typical, and parts of western Norway receive more that 4 m. Thunder storms can periodically move in from the sea as part of large low pressure cells, and local thunder storms can also form above the landmass during summer. Lightning is frequent, but the high humidity creates much less optimal conditions for natural ignition as compared to more continental areas. The highest frequency of natural fires is expected in the boreal forests of the country’s eastern lowlands, southwestward to the divide, and in the most continental part of central Norway.
The rugged topography, with its many depressions, valleys, bogs, lakes and wetlands, creates natural fire barriers. Measured on an international scale, relatively small areas are therefore expected to burn in individual fires. Differences in frequency of lightning, distribution of fuels, and the varying climatic conditions create distinct frequency gradients with respect to the occurrence of natural fires.
However, a basic problem in defining the natural regime is that it is difficult to separate the fires ignited by lightning from anthropogenic ignition sources. The cultural fire regime, that is to say forest and range fires due to human activity, seems to have been very important in Norway, and somewhat underestimated in current fire debates. Globally, humans have used fire for more than one million years. When the first tribes of hunters and gatherers migrated into Scandinavia after the last glaciation 10,000 years ago, fire was the oldest, and together with the axe, their most important technology. Little information seems to be available , however, about the pioneer hunter and gatherer’s use of fire. That they both intentionally and unintentionally ignited and burned large areas seems obvious. More uncertain is whether they also used fire in forested environments as part of the actual hunt, or to enhance herbivore populations of typical “fire followers” such as moose and roe deer.
From the period when the glaciers began to retreat, increasing human traffic influenced the coastal ecosystems. Maps showing traditional trade routes document the importance of ocean resources and the coast areas for the Norwegian population and settlements through several historic epochs. Already during the Viking Age (800 – 1000 AD) and throughout the 12th and 13th centuries, a considerable network of trade was developed with connections to the entire European continent.
This activity, which is exemplified below, has prompted forest fires of a character not commonly found in the more continental areas further east in Fennoscandia. As part of tactical dispositions associated with international timber trade, actors from the Hanseatic League in Europe (a historic trade association) burned forests in the coastal areas, destroying timber resources to prevent competition from Norwegians. The extent of such burnings was so considerable that the Danish-Norwegian king at that time (Håkon the 6th Magnusson, 1355 – 80) addressed the fires in court negotiations with the Hanseatic countries on the continent. During periods of actual unrest, tactical burning of forests was apparently common along the coast. Tactical use of fire has even been mentioned in certain places in Sweden in the north, for instance in conflicts between Sami reindeer herders and colonizing agriculturists.
Another example of the widespread use of fire along the coast is the burning of pastures, which has created extensive areas of Calluna heaths. These are purely fire-induced, man made ecosystems developed for the purpose of year-round animal grazing.
Huge forested areas have been burned in connection with the clearing of farmland during the periods of settlements. The use of fire has also been the basis for a variety of important swidden agricultural techniques (Norwegian: “svedjebruk”). While the natural fires are expected to have occurred in the driest and least productive forest types, swidden agricultural use has been most frequent in the forest types developed on the more fertile soils. Fire has also been used recently by modern forestry to regenerate clearcuts. The practice of such burning in Norway, however, has been rather limited.
It is concluded that even if the natural fire regime has been of a cool and moderate type, this does not mean that Norway’s forests have historically burnt less than in more continental areas. A survey of available sources indicates that anthropogenic ignition, i.e. culturally induced fires, has influenced the development of vegetation and the landscape to a much greater extent than is generally realized. It should be noted that it is fully possible to start crown fires of high intensity, even in the coastal areas, if ignited during an appropriate period. When a burn has first started in a steep area where fertile soils and high precipitation have led to a considerable accumulation of fuel over a longer period, subsequent erosion and other post-fire effects can be of an even greater ecological significance than in more levelled continental areas. It is therefore urgent for management to gain better understanding, through new research, of how the historical (natural and cultural) fire regime has shaped the soil, flora and fauna in Norway.
However, it must be assumed, due to extreme ecological variabilities, that there still may exist extensive areas of fire refugia which have never burned during the post glacial epoch. It is possible that the Norwegian coastal mountains and higher elevated forests may be important as refugia for “fire avoiders” and species dependent on continuity in Fennoscandia. This can only be evaluated through further ecological research. The attitude towards wildfires changed considerably during the middle and end of the last century due to industrialization, higher prices and a greater demand for timber resources. More aggressive fire fighting has become the core of management, and procedures today are very efficient. During the most recent period, the size of burned areas has subsequently decreased considerably.
Today, however, a more objective view of the importance of fires to flora and fauna is again on the verge of changing attitudes. We know that fire specialists, so-called pyrophilous species, are components of Norwegian flora and fauna, such as Cranesbill (Geranium bohemicum) and Pill-headed sedge (Carex pilulifera), which are almost exclusively dependent on fire for survival. The number of invertebrates associated with scorched and charred substrates, dead wood and other resources in burned areas is considerable. An example is the fire beetle (Melanophila acuminata), whose larvae develop in freshly burnt wood. Among the vertebrates, “fire followers” such as the moose (Alces alces), roe deer (Capreolus capreolus), woodpeckers and even the Ortolan bunting (Emberiza hortulaua) occur. Conservation efforts towards some of these components in the Norwegian flora and fauna will rest on a better knowledge about forest fire as a disturbance and ecological factor. The Norwegian landscape with its historical fire regime, soils, flora and fauna, is unique; and it will never be possible to apply the results of research in other countries to the understanding of the Norwegian fire regime. It is also crucial in research and management to identify the fire regime more precisely before extensive new prescribed fire management programs are eventually introduced into the Norwegian landscape.
A report on the knowledge of fire ecology and the Norwegian regime is now being printed as part of a combined effort from the Directorate for Fire and Explosion Prevention; Department of Biology, University of Oslo; Directorate for Civil Defence and Emergency; Directorate for Nature Management; and Forest Insurance Company, Skogbrand (Bleken et al. in print).
Bleken, E., Mysterud, I. & Mysterud, I. Forest fire and environmental management. A report on forest fire as an ecological factor. Technical report. Directorate for Fire and Explosion Prevention; Department of Biology, University of Oslo <in Norwegian, with English summary> (In press)
Tab.1. Number, area burned and average size of forest and range fires in Norway 1986-96.
Source: Combined data, Statistics Norway, Directorate for Fire and Explosion Prevention.
Number of Fires
Area Burned (ha)
Average Size of Fire (ha)
From: Ivar Mysterud & Iver Mysterud and Erik Bleken
Department of Biology
University of Oslo
P.O.Box 1050 Blindern
N – 0316 Oslo
Directorate for Fire & Explosion Prevention
N – 3101 Tönsberg