Landforms

• Innhold
• Description of landforms
• Assessed landforms
• Ecosystem types on the Red List
• Impact factors
• Existing knowledge
• Expert Committee
• References

A landform is defined as a "more or less distinct terrain form (a surface form on land or a formation on the bottom in saltwater or freshwater systems) that provides a common set of characteristics on the basis of features that are often caused by a single, or a combination of, distinct landform-creating (geomorphological) processes" (Halvorsen et al. 2016). In other words, landforms are important landscape elements that are associated with specific natural physical processes.

Description of landforms

Landforms comprise everything from small details such as glacial stria to vast landforms such as a volcano or u-shaped valley. Landforms are created by different processes that affect the surface of the land. Many of these processes are ongoing even today and landforms that are created are active in the sense that the landforms are still being formed. A good example is the landform meander which can be formed when water flows through fine-grained sediments.

If the process that has shaped the landform has ceased, the landform becomes a fossil in the sense that the formation process is complete and the landform is no longer active. The list of landforms that is used in this work does not distinguish between active and fossil landforms. This has been a challenge particularly in connection with assessing the degree to which they have been impacted and the definition of loss of active landforms. Impact factors can lead to the process more or less ceasing. This can represent loss of the active landform, but not of the fossil type. We have attempted to resolve this by describing which assessments have been made in the criteria documentation for each and every landform, where this has been possible. For some landforms it would have also been natural to differentiate between terrestrial and marine environments, as the risk profile for each differs substantially. General information about Norwegian landforms is available in Gjessing 1995, Sulebakk 2005 and Ramberg et al. 2013 (Norwegian language only).

Assessed landforms

The assessment entities that have been used correspond to the list contained in Nature in Norway NiN (Halvorsen et al. 2016). NiN 2 defines a total of 85 landform entities. These are divided into 14 groups (including peatland formations which are assessed under Wetlands) based on the processes which have formed them. Examples of such processes include frost processes, chemical dissolution of calcium carbonate (limestone and marble), erosion and flowing water. A process seldom works in isolation, so landforms can be grouped in several ways. The list of landforms also contains a few surface formations, the existence of which is dependent on the bedrock.

In NiN 2, landforms are part of the descriptive classification system. It has been a prerequisite for the Red List assessments that the list of landforms is to be used directly and not supplemented with other characteristics from NiN's descriptive system. We have adhered to this as much as possible. In some cases this has resulted in landforms with different forms, different geographic distributions, that exist as both active and fossil landforms, and are affected by very different factors, are nonetheless treated as a single assessment entity. In such cases we have discussed this separately.

We have assessed the landforms in the following manner: first we have reviewed the list and identified landforms which are obviously not exposed to impact factors that would require them to be red-listed. This is primarily justified on the grounds that they may be extremely common or exist in areas where the impact factors are of scant relevance. These landforms were initially assessed as being of Least Concern LC without comprehensive analyses being undertaken. One landform was assessed as Data Deficient DD. The remaining 44 landforms have been assessed in accordance with the applicable guidelines for Red List assessment. This comprises quantitative estimations as well as qualitative assessments where the available knowledge is too poor to make a quantitative assessment. The quantitative assessments have limitations associated with data quality. The result of the estimations is therefore interpreted qualitatively and with discretion.

In order to conduct a Red List assessment of a landform, one must first define when the original landform has Collapsed. When a landform has lost a large amount of its distinctive characteristics, to the degree that it can no longer be defined as the original landform, it is defined as Collapsed. One challenge we have stumbled upon in our work has been associated with the list of landforms not differentiating between active and fossil landforms. this has been a challenge, particularly in connection with the assessment of active landforms, where the impact factors can lead to the process more or less ceasing. This can be interpreted as the active landform has Collapsed, even if a fossil landform still exists. We have resolved the challenge by providing comments in the criteria documentation for the relevant Red List assessments.

There is some degree of uncertainty in the data because it has been digitalised from geological maps using cartographic generalisation. The proxy value is estimated from the extent to which regional surveying and expected national distribution of the landform entity are representative in proportion to the areas that are surveyed in detail in the Geological Survey of Norway's Quarternary geological database. The proxy value is in other words an estimate, not a calculation. In many cases we have selected the proxy value 1.3, either because data from regional surveying is included in the database, or because it is expected that the largest part of the landform is located within the area that has been surveyed in detail. We do not have a precise overview of the size of this effect for the various landforms.

Ecosystem types on the Red List

In total 27 landforms are red-listed. Two of these are Critically Endangered CR; Earth pillar and Tufa. Both are Critically Endangered due to a restricted distribution area with an ongoing decline in quality. Tufa is found in its most characteristic form at two small, separate localities on Svalbard. It is these that are assessed. Other calcium carbonate precipitates also exist on a much smaller scale on the Norwegian mainland but there is insufficient information to assess these.

Dripstone is assessed as Endangered EN. More than 80 % of the total area is degraded and the degree of degradation, due to abiotic factors, is assessed as being more than 50 %.

There are 12 landforms which are assessed as Vulnerable VU. These comprise the seven glacier types, as well as Delta, Meander, Gully in marine clay, Limestone cave and Aeolian sand dunes. All of the seven types of glaciers are red-listed due to a reduction in area over periods of 50 years (both in the past and projected). Gully in marine clay and Aeolian sand dunes have had corresponding declines associated with land use change. For Meander and Limestone cave more than 50 % of the area is degraded and the degree of degradation is also greater than 50 % over a 50 year period. Delta is red-listed due to both area loss and degradation.

Twelve (12) landforms are assessed as Near Threatened NT (Kettle hole, Alluvial plain, Alluvial fan, Terrestrialised marine clay plain, Levée, Oxbow lake, Subterranean river, Eroded river bank, Limestone ridge, Coastal cave, Beach ridge, and Quick clay landslide). One landform, Black smoker is defined as Data Deficient DD, i.e. there is a lack of information regarding the number of landforms and the degree to which potential impact factors may threaten them. Black smokers are found at great depths along mid-ocean ridges. There is a single known occurrence in Norway. The landform is associated with outflows of hot geothermal springwater and is identified as a possible resource for the extraction of minerals.

A single natural system is also assessed by this group of experts: Permanent snow and ice. This assessment is closely associated with the assessments of glacial types and has been assigned to the category of Near Threatened NT.

Impact factors

Fossil landforms

Impact factors are primarily associated with direct encroachments on the area and land use. In addition to being subject to general land use impacts, a number of landforms are resources that are specifically exploited, such as various sand and gravel deposits. In this case there is a direct connection between the landform and the resource (sand and gravel). Landforms of this type include fossil delta deposits (a part of the landform Delta). Wear and tear associated with human traffic and natural erosion processes are also registered as impact factors.

We have attempted to adjust the assessment of the impact factors to the scale of the various landforms. Small landforms are destroyed by small encroachments, whilst the larger landforms are more robust. This is taken into consideration with assessment of the level where we define when a landform has collapsed. For example, Dripstone formations that exist in certain Limestone caves are extremely vulnerable and it does not take much to destroy them, whilst Terrestrialised marine clay plains form large areas. Even if there are extensive impacts on the Terrestrialised marine clay plains they will still remain intact as clay plains and appear as such in the landscape.

The impact factors on the seabed are naturally very different from those on land. Land use is different and often less intense, but even here there are physical impact factors that have the potential to destroy or damage landforms. An example of a typical marine impact factor is bottom trawling.

Active landforms

Where active landforms are concerned there is a broader spectrum of impact factors that lead to degradation. This applies particularly to landforms caused by erosion and deposition in rivers, where the impact factor of watercourse regulation is especially relevant. This involves not only altered water flows but also altered flood regimes. The landform creation processes clearly have the greatest effect during floods, and flood mitigation therefore affects the active processes to a large degree. The regulation of watercourses in Norway is comprehensive and an overview enabling the calculation of the impact of regulation on each specific landform (stretch of river), in each individual river across the country, is still lacking. A large proportion of Norwegian hydropower development occurred in the period 1970-1985, which is the timespan that is encompassed by the criteria for red-listing. When such data becomes available on a nationwide basis, more direct analyses of the actual size of this impact will be possible.

Climate

The ecological condition of many landforms is directly impacted by variations in climate. For many landforms this is associated with the activity of active frost processes. However, for glacier formations their very existence is connected to the climate. The glaciers are dependent on winter precipitation in the form of snow and on the temperature in summer. If more snow and ice melts during summer than has been added during winter the mass balance is negative. If the glacier lies below the elevation at which there is a balance between the melting and addition of snow, the glacier becomes climatically dead. In our work we define this as the landform has Collapsed.

In terms of the activity of frost processes we have been cautious about suggesting that the relevant landforms will Collapse within 50 years (the period of time used in the assessment criteria). It is partly the case that many of the landforms will metamorphose to a fossil state without disappearing, and partly that we lack knowledge that would enable us to assess the consequences of climate change within the climate scenarios on which the Red List is based. Increased knowledge of landform processes, as well as climate change developments, will lead to more accurate assessments for future Red List assessments.

Existing knowledge

The quantitative assessment that is based on databases that have been procured in connection with geological sediment mapping on behalf of the Geological Survey of Norway. Regional data at a scale of 1:250 000 is available for the entire country, while about half of the country is covered by map data at a scale of 1:50 000 or better. The latter is primarily used for analysis but for specific landforms, and for soil type data, regional data is also used. Figure 1 shows an example of a dataset (kettle holes) where yellow indicates the areas that are mapped in detail, while grey represents the remaining areas.

The data we used to assess loss of area is an infrastructure index created with the assistance of a GIS analysis of human actvity such as roads, buildings and infrastructure. The data material is collected from national map data sources and partly transformed in connection with work with the Landscape type map of Norway (Erikstad et al. 2015). A number of these data sets are in raster format, which means they have been transformed into grid squares, or pixels, that indicate whether an object is present or not. The resolution, that is the grid squares that are used, are 100 x 100 metres, and along with the map inaccuracy in the landform specification there is a limitation on the level of detail in the analysis. Nevertheless we consider it sufficient to establish a reasonable national overview, even though it should be an aim to improve the quality of the data. The calculation procedure is provided for each individual landform.

For the qualitative analyses, data and interpretations of available research on the respective landforms are used. Both general information from regional surveying is used or more detailed research that can be transferred to a national assessment.

Expert Committee

The members of the expert committee for Landforms were Lars Erikstad (chair), Rolv Dahl, Tom Heldal and Berit Husteli. 

References

Erikstad L, Uttakleiv LA, Halvorsen R (2015). Characterisation and mapping of landscape types, a case study from Norway. Belgian J. Geogr. 3.

Gjessing J (1995). Norges landformer. Universitetsforlaget. 5. opplag. [in Norwegian]

Halvorsen R, et al. (2016). NiN – typeinndeling og beskrivelsessystem for natursystemnivået. – Natur i Norge, Artikkel 3 (versjon 2.1.0): 1–528 (Artsdatabanken, Trondheim; http://www.artsdatabanken.no.)  [in Norwegian]

Ramberg IB, Bryhni I, Nøttvedt A, Rangnes, K (eds.) (2013). Landet blir til, 2. Utgave. Norsk Geologisk Forening, 2013.  [in Norwegian]

Sulebakk JR (2007).Landformer og prosesser. En innføring i naturgeografiske tema. Fagbokforlaget. [in Norwegian]