Two ecosystem types, Ultramafic woodland and Lime-rich deciduous woodland are assessed as Endangered EN. Both have a declining and limited area of distribution, and more than half of the total area is degraded. Several ecosystem types are assessed as Vulnerable VU (7 types) or Near Threatened NT (3 types). In general, the most significant influence on forest ecosystems is intensive plantation forestry.
- Description of forest
- Assessed ecosystem types
- Red listed ecosystem types
- Impact factors
- Existing knowledge
- Expert committee
Forest covers almost 40 % of Norway's area and is of great importance for biodiversity and as an economic resource, both as pasture for livestock and as timber. Forests have therefore been subject to considerable human influence for many hundreds of years, although the nature of the influence has changed since the Second World War with the widespread introduction of plantation forestry. This factor, combined with an increase in the construction of housing, roads and other infrastructure, climate change, and the establishment of alien species, has changed forest biodiversity and the structure and function of forest ecosystems.
Description of forest
Forest, according to Nature in Norway (NiN), is natural ground that is strongly marked by the prolonged influence of trees, and which at a given point in time is covered in trees, or in the recent past has been, or the near future is expected to again be covered in trees. In NiN's Terrestrial Systems T there are two major types of forest:
- Forest T4 (also called forest below) with 20 minor types defined by their placement along complex environmental gradients for lime content KA, drought risk UF, and the influence of freshwater springs KI.
- Alluvial Forest T30 with 7 minor types defined by sediment grain size S1, water impact VF, the influence of freshwater springs KI, and erosion risk ER.
Forest or woodland comprises approximately 38 % of Norway's area (mainland, excluding marine areas), and is composed of the major types Forest (approximately 93 %) and Alluvial Forest (approximately 1 %), while the remainder is made up of forest in wetlands. Forests encompass a range of ecosystems with great significance for important ecosystem processes and biodiversity. More than half of Norway's known species are associated with the various forest habitats and mediums, including 48 % of its endangered species. The forest ecosystem processes and species are connected with natural disturbances on different scales in time and space. Use of forests by humans through the ages, and especially over the past hundred years, has led to considerable changes in the structure of forests, the types of degradation and speed of succession, as well as species composition.
Assessed ecosystem types
Initially, the two major types Forest T4 and Alluvial Forest T30 were assessed. Neither of these basic types satisfied the criterion for separate assessment (i.e. that the entity has less than 20 occurrences in 10 x 10 km2 grids).
The assessment also included different entities placed along the defining complex environmental gradients of lime content KA, drought risk UF and the influence of freshwater springs KI, combined with bioclimatic regions, dominant groups of tree species, and a smaller selection of other environmental gradients. Combinations that would probably be subject to a qualitatively different impact and a Red List category at least one grade higher than the major type, were selected for assessment. For Forest this mainly applied to forest along the rich section of the lime gradient, in addition to forests in the boreo-nemoral and southern boreal zones, and in a strongly or clearly oceanic climate zone, as well as individual entities on special bedrock (olivine) or substrate (gravel/sand). The expert group was unable to find that Alluvial Forest could be subdivided into entities that satisfied the criteria.
It is otherwise worth noting that NiN definitions used to specify the individual entities, are in several cases slightly different than for entities with similar names that were previously used. Furthermore, there are some entities in the Red List 2011 that were not assessed in 2018: Continental forest stream gorges was defined as a landscape element in NiN version 1, an ecosystem type that is not currently defined in NiN 2. The criteria for selection of assessment entities in 2018 does not allow the use of individual tree species, only groups of tree species, as a basis for sorting. Consequently Beech woodland is not assessed as a separate entity, but healthy stands are grouped with Healthy lime-rich deciduous woodland and somewhat drier stands with Deciduous woodland with forbs. Since natural objects are not a basis for Red List assessment, neither is the selected ecosystem type hollow oaks assessed.
Red listed ecosystem types
The major type Forest T4 is significantly impacted by forestry over an exceedingly large part of the area but the expert group has not considered the changes in the past 50 years, or probably in the next 50 years to be so extensive that the type should be red-listed as near threatened. The most endangered minor types of Forest are Ultramafic woodland and Lime-rich deciduous woodland. Both are assessed as being Endangered EN, with a very limited area of distribution in continuing decline, and with more than 50 % of the total area being more than 50 % degraded.
Several entities are assessed as Vulnerable VU, partly because of a limited distribution and degradation (Boreal rainforest and Boreo-nemoral rainforest), the pervasive effects of forestry (Boreal rainforest and Lime-rich spruce forest), a combination of area loss and degradation over the past 50 years (Lime-rich pine forest with forbs) or estimated future area loss and degradation (Deciduous woodland with tall forbs). Other entities are assessed as Near Threatened NT because of different impacts over the past 50 years or predicted corresponding impacts in the next 50 years: Spruce forest with tall forbs (extensive forestry impacts), Lime-rich pine forest on sand substrate (forestry, construction/land-conversion) and Healthy lime-rich deciduous forest (new pests due to climate change). A reduction or change in the practice of grazing livestock in forests has led to the deterioration of Grazed woodland, but not so much that it is assessed as Near Threatened.
The major type Alluvial Forest T30 is assessed as Vulnerable VU due to watercourse regulation, flood control and other encroachments in or along watercourses in the past 50 years. The expert group did not find a basis for assessing other entities of Alluvial forest.
For Forests in general, the dominant influence is forestry, especially intensive plantation forestry with uniform timber production across the entire plantation and short rotation periods, an increasing degree of soil scarification, usually planting and tending of the stands, as well as defending against natural disturbances like forest fires (Essen et al. 1997, Kuuluvainen 2009). This changes the composition of the forest in terms of the age and species of trees, the occurrence of important substrates for species diversity such as dead wood and old treees, as well as the landscape pattern of forests of different age classes. The type of forestry management and the ecological effects of forestry activity vary with the soil productivity and dominant tree species. Spruce, particularly when it is growing on productive soil, is suitable for very intensive forestry practices, the ecological impacts of which deviate considerably from natural disturbances. Furthermore, in forests where the characteristic species diversity is dependent on a stable and very humid microclimate, forestry activities will lead to desiccation that radically changes the species communities.
For forests close to lowland towns and villages, and along important roads etcetera, construction or measures that prevent natural disturbance processes (such as the prevention of landslides) could be more important impact factors than forestry. Land conversion primarily represents an irreversible encroachment and loss of area. Lime-rich forest areas in the Oslo fjord area and around Trondheim fjord are particularly exposed to such impacts. Some occurences of forest on particularly mineral rich bedrock, such as Ultramafic woodland, are also strongly influenced by mining (Holtan 2008).
The spread of (alien) pests, especially fungi or insects, can be a clear threat to tree species such as elm, ash and beech. These tree species constitute a characteristic and dominant element in forests in the boreal-nemoral zone. With a considerable reduction in the distribution of these tree species due to pests, and their replacement with for example, conifers, forests where this occurs will change their ecological characteristics to a considerable degree.
Livestock grazing and harvesting forages within forests can also have a noticeable impact on forest biodiversity. Changes or discontinuation of grazing, or other foraging, in forest types characterised by such traditional activities, will also change the distribution or condition of such forests.
For Alluvial Forests, watercourse regulation and flood prevention measures are important impact factors. They change the flood regime which is an important structural factor for Alluvial forests. Flood prevention measures and the conversion of floodplains to farmland, or areas for roads, industry or housing, lead to a direct loss of area. Forestry will also lead to a change in the structure and biodiversity of Alluvial Forests.
Dominant forest trees such as spruce and pine represent a large economic resource which has been surveyed by the Norwegian National Forest Inventory since 1918. This surveying has given a representative picture of areas and volumes of the most important forest trees, in addition to the distribution of soil types in the forest. The categorization of soil types has primarily been based on a traditional understanding of variation in field vegetation, rather than a systematic science-based classification. Neither have the Norwegian National Forest Inventory surveys been able to provide statistics for rarely occurring types or to capture entities that are traditionally understood as being particularly important for biodiversity. In recent decades such entities have been surveyed as part of environmental management work based on conservation plans, or surveys of entities that are important for biodiversity. This type of survey work does not provide representative statistics and is not based on systematic scientific classification. Nevertheless, nature surveys conducted by the Norwegian National Forest Inventory and environmental management authorities, together with a long series of vegetation ecology studies, provide most of the available data and knowledge. This information is collated in a series of Norwegian-language publications from the last 20 years: popularising of scientific results from the Norwegian National Forest Inventory (Larsson & Søgnen 2003), botanical investigations of vegetation (Fremstad 1997), evaluations of conservation areas (Framstad et al. 2002, 2010, 2017; Blindheim et al. 2011) and summaries of registrations in different forest types – boreal deciduous woodland (Bendiksen et al. 2008), stream gullies (Evju et al. 2011), pine forest on sand substrate (Brandrud & Bendiksen 2014), deciduous woodland (Blindheim et al. 2015), rainforest (Blom et al. 2015; Gaarder et al. 2013), lime-rich coniferous forest (Brandrud & Bendiksen 2018).
The NiN system represents a science-based classification and description of Norwegian nature. Nevertheless, the empirical knowledge and data regarding NiN entities and variables still has areas of weakness. There is therefore a great deal of uncertainty associated with the connection between the existing data and NiN, something which results in both an uncertain representation of NiN entities in nature and the areas which they cover. In addition, several entities are poorly surveyed, especially in Boreal deciduous woodland, or the surveyors have used different criteria or categorizations to identify and delimit entities, perhaps especially with regard to forests characterized by their use for grazing or forage. Lastly, we have generally poor knowledge about the dose-response relationships between impact factors and their effects, so that it is difficult to ascertain the degree to which these influences bring about changes in the ecosystems' characteristics. Not least it is difficult to form a precise picture of the extent and condition of the ecosystem types over a 50 year period, as the number of registrations was much lower than today. It is therefore necessary to rely on the more or less sound assessments of experts in the application of the criteria for red-listing of ecosystem types.
The expert committee for forest was composed of Erik Framstad (chair), Egil Bendiksen, Hans H. Blom and Anne Sverdrup-Thygeson.
Thank you to the following for sharing their views on different assessment entities: researcher Tor Erik Brandrud (NINA), biologist Geir Gaarder (environmental evaluation), biologist John Bjarne Jordal, and researcher Ellen Svalheim (NIBIO). In addition, many individuals have given valuable contributions to the draft of the assessments.
Bendiksen E, Brandrud TE, Røsok Ø (ed.), Framstad E, Gaarder G, Hofton TH, Jordal JB, Klepsland JT, Reiso S (2008). Boreale lauvskoger i Norge. Naturverdier og udekket vernebehov. NINA Rapport 367. [In Norwegian.]
Blindheim T, Thingstad PG, Gaarder G (eds.) (2011). Naturfaglig evaluering av norske verneområder. Dekning av naturtyper og arter. NINA Rapport 539. [In Norwegian.]
Blindheim T, Hofton TH, Reiso S, Gaarder G, Brandrud TE, Thylén A, Blumentrath S, Hjermann D (2015). Status for edellauvskog i Norge per 2014. Oppsummering av nasjonale kartlegginger av naturtypen 2009-2014. BioFokus-rapport 2015-5. [In Norwegian.]
Blom HH, Gaarder G, Ihlen PG, Jordal JB, Evju M (2015). Fattig boreonemoral regnskog – et hotspot-habitat. Sluttrapport under ARKO-prosjektets periode III. NINA Rapport 1169. [In Norwegian.]
Brandru TE, Bendiksen E (2014). Sandfuruskog og sandfuruskogsopper. Viktige områder for biologisk mangfold. NINA Rapport 1042. [In Norwegian.]
Brandrud TE, Bendiksen E (2018). Faggrunnlag for kalkbarskog. NINA Rapport 1513. [In Norwegian.]
Esseen P-A, Ehnström B, Ericson L, Sjöberg K (1997). Boreal forests. Ecological Bulletins 46: 16-47. [In Norwegian.]
Evju M, Hofton TH, Gaarder G, Ihlen PG, Bendiksen E, Blindheim T, Blumentrath S (2011). Naturfaglige registreringer av bekkekløfter i Norge. Sammenstilling av registreringene 2007-2010. NINA Rapport 738. [In Norwegian.]
Framstad E (ed.), Blindhem T, Erikstad L, Thingstad PG, Sloreid S-E (2010). Naturfaglig evaluering av norske verneområder. NINA Rapport 535. [In Norwegian.]
Framstad E (ed.), Blindheim T, Granhus A, Nowell M, Sverdrup-Thygeson A (2017). Evaluering av norsk skogvern 2016. Dekning av mål for skogvernet og behov for supplerende vern. NINA Rapport 1352. [In Norwegian.]
Framstad E, Økland B, Bendiksen E, Bakkestuen V, Blom H, Brandrud TE (2002). Evaluering av skogvernet i Norge. NINA Fagrapport 54. [In Norwegian.]
Fremstad E (1997). Vegetasjonstyper i Norge. NINA Temahefte 12. [In Norwegian.]
Granhus A, Hylen G, Nilsen J-EØ (2012). Skogen i Norge. Statistikk over skogforhold og skogressurser i Norge registrert i perioden 2005-2009. Ressursoversikt fra Skog og landskap 03/12. [In Norwegian.]
Gaarder G, Fjeldstad H, Hanssen U (2013). Boreal regnskog/kystgranskog på Fosen i Sør-Trøndelag. Miljøfaglig Utredning Rapport 2013:32: 1-51. [In Norwegian.]
Holtan D (2008). Olivinskogene i Norge – en oppsummering av status og verdi. Fylkesmannen i Sogn og Fjordane, Rapport 2008:06. [In Norwegian.]
Kuuluvainen T (2009). Forest management and biodiversity conservation based on natural ecosystem dynamics in Northern Europe: The complexity challenge. Ambio 38: 309-315.
Larsson JY, Søgnen SM (2003). Vegetasjon i norsk skog. Vekstvilkår og skogforvaltning. Landbruksforlaget. [In Norwegian.]