Planar elevation

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Largely natural moorland area in the Ohligser Heide (Solingen); frequent azonal vegetation in the planar level of the north-west German low mountain range

Planar altitude level (from Latin planus = flat, flat - even Planarstufe , Eben level , lowland stage (Engl. Plains ) and occasionally planar vegetation zone ) is the orographic term for (low) levels in terms mountain areas and their vegetation .

The site conditions of the plains for the flora correspond to the zonal conditions of the climatic zone in which the mountains are located; Extrazonal conditions due to the mountain climate are not yet to be expected here. It is generally characterized by gentle slopes and a few elevations with little relief energy (maximum difference in altitude of 50 m). Its upper limit is drawn at the foot of the mountain according to the respective ecological requirements when there is a certain change in natural plant formations . The next higher vegetation level is either the colline or montane altitude level .

The term planar is common for the temperate zone . In Mediterranean mountains, the different designation thermomediterranean (sometimes also Mesomediterranean , but inconsistent) is often used in order to make the vegetation differences to the mountains of the adjacent temperate zone clear through the terminology.

In the other subtropics and in the dry tropics , a planar step is sometimes mentioned. In the humid tropics to height Windwärts Although the change species composition of the vegetation of the formation, but lowland rainforest remains dominant until 1000/1400 meters, so it would be misleading here by planar stage to speak). Also for polar mountains no planar level is defined (in the high latitudes there is already tundra in the plain, which reaches hundreds of meters in height and is described everywhere as alpine vegetation. Similar to the polar areas, a boreal level comprises several orographic height levels: It ranges from the planar to the Montan level, but there are already differences in the forest formations between the plains and mountains, so that the planar level is delimited separately, for example as thermoboreal .

Basically, terms that refer to global zone concepts - such as arctic, boreal, Mediterranean, subtropical or tropical - inevitably (in most cases) refer to the planar lowlands. Several authors form the name of the level simply from the typical vegetation: In humid, cool-temperate mountains, the planar (colline) level is roughly called the deciduous forest level (not to be confused with the montane forest level ). In addition, some authors use their own names - such as the Peruvian geographer Javier Pulgar Vidal , who defined two planar levels for the tropical Andes: the hot and humid Chala for the western foot and the hot and dry Omagua for the eastern.

Heights of up to 100 meters above sea level can, with the exceptions mentioned, be included in the planar level. However, the specific upper limit is set separately for each mountain range according to the ecological definition .

If the climate and vegetation in the rising foreland of a mountain range do not yet show any significant differences to the plain, many authors combine the planar level with the lowest mountain level to form a planar-collinear or collin-planar altitude level .

From a forestry point of view and in common parlance , the planar level, together with the colline and submontane level, belong to the lowlands .

nomenclature

The terms planar, kollin , montan , alpine and nival belong in geobotany , biogeography and ecology to the most widespread, “classic” nomenclature for altitude levels with their respective typical climates and potential natural vegetation . Although these names, which originate from traditional alpine research , originally only referred to humid mountains in temperate latitudes , today they are also used (with the exceptions already described) for mountains in other climatic zones . Because of this, there can be no generally applicable definitions, as the gradation is always based on the actual conditions of a specific mountain range. Some authors therefore use different terms and sequences - especially in completely different ecological conditions - in order to avoid confusion and incorrect conclusions.

Ecological guidelines

Although the prairie plains in the USA rise from around 200 m on the Mississippi westward to up to 2000 m, they are counted as planar plains due to the steppe vegetation that dominates everywhere

The plant formations of the plains should represent the expected zonal vegetation of the respective climatic zone , so that neither the height above sea level nor their terrain formations may influence this climax condition. The determination of the upper limit of the planar vegetation level depends on the perspective: On the one hand, it extends higher into the mountains, the smaller the climatic differences. On the other hand, however, the author determines the number of altitude levels and the scale level of the existing ecosystems (e.g. concrete, rather small-scale forest communities such as oak-hornbeam forest , grove -beech forest or limestone grasslands - or highly abstracted large habitats such as summer green deciduous forest , mountain coniferous forest or highland steppe ) , so that comparisons of different Regions are not very meaningful.

If a mountain range forms the border between two climatic zones and is described separately from the surrounding area, the consideration of the lower elevation levels is more vegetation-related, so that different names within a mountain range can be used. This applies, for example, to the Alps , which in the north have a planar level with mixed deciduous forests and in the south at the same altitude instead a thermo-Mediterranean altitude level with hard- leaf vegetation . Orographically, there are two planar levels with different climates.

Strictly speaking, many so-called planar steps that exceed heights of a few hundred meters are orographically (according to the terrain profile) more collin or even montane steps , so that some authors call for more unambiguous names.

Examples of height settings and original vegetation

The following table shows the enormous differences in the lowest vegetation level using a few examples (mostly mountainous areas) from all eco-zones:

Eco zone Mountains / Region (Country) to vegetation
Damp middle widths Bergisches-Land / Sauerland ( Germany ) 100 m for example grove-black alder alluvial forest, black alder-hornbeam forest, bird cherry-black alder-ash forest
Damp middle widths Northern Swiss Alps 200 m Oak-rich deciduous forests
Boreal Zone Central Kamchatka Mountains (Russia) 200 m Alder-poplar-willow forests
Summer humid tropics Popocatépetl (Mexico) 200 m Mesquite thorn bush savannah
Summer humid tropics Tanzania's coastal plain 200 m Semi-evergreen monsoon rainy season forest
Winter humid subtropics Southern Maritime Alps (France) 350 m Holm oak / cork oak forests
Winter humid subtropics Teide north slope (Tenerife) 300/400 m Infra-Canarian milkweed succulent bushes
Always humid tropics Equatorial Andes (Venezuela, Colombia, Ecuador, Peru) 500 m (lower tierra caliente , but rarely differentiated) Evergreen floodplain and lowland rainforest
Winter humid subtropics Southwest Caucasus (Georgia) 600 m Evergreen colchic laurel forest
Polar zone Brooks Range Alaska 600 m (planar-kollin-montan-alpin *) tundra
Always humid tropics Kinabalu (Borneo, Malaysia) 350/600 m Dipterocarpean lowland rainforest
Damp middle widths Pacific Cascade Range (United States) 1000 m Temperate coastal rainforest
Always humid subtropics Sichuan Basin (PR China) 1000 m Evergreen oak and laurel forest
Tropical / subtropical arid areas Ahaggar Mountains (Algeria) 1000 m Hot desert
Tropical / subtropical arid areas Nanga Parbat south cover (Pakistan) 1100 m Dry steppe and semi-desert
Dry middle widths Rocky Mountains in Colorado (United States) 1500 m Dry short grass prairie

*) = In the polar regions there is no exclusively planar plant formation, as tundra or cold desert predominate up to alpine heights

Other special features

As draining water collects in the planar plains, the largest azonal habitats such as swamps , bogs and large floodplains can be found here . In the depressions of the planar elevation, the formation of cold air lakes can occur.

Anthropogenic influence

The natural vegetation of the plains beyond the polar and subpolar zones - in permanent settlement areas - is severely impaired worldwide, as it is often best suited for agricultural use and has been converted into cultivated landscapes .

literature

  • Gustav Wendelberger : About the independence of the planar step , Verh. Zool.-Bot. Ges. Austria 135 (1998), pages 271-287

Individual evidence

  1. ↑ Hans Ernst Hess, Elias Landolt, Rosmarie Müller-Hirzel, Matthias Baltisberger: Identification key for the flora of Switzerland and adjacent areas , page 29 limited preview in the Google book search
  2. ↑ a b c d e f g h i j k l Conradin Burga, Frank Klötzli and Georg Grabherr (eds.): Mountains of the earth - landscape, climate, flora. Ulmer, Stuttgart 2004, ISBN 3-8001-4165-5 . Pp. 32, 67-83, 128, 174, 184-185, 193, 205, 255, 332, 372, 385, 401-416.
  3. ↑ Georg Grabherr: Color Atlas of Ecosystems of the Earth. Ulmer, Stuttgart 1997, ISBN 3-8001-3489-6 . Pp. 224-225.
  4. ↑ a b c d Michael Richter (author), Wolf Dieter Blümel et. al (ed.): Vegetation zones of the earth. 1st edition, Klett-Perthes, Gotha and Stuttgart 2001, ISBN 3-623-00859-1 . Pp. 301-312
  5. ↑ Jörg S. Pfadenhauer and Frank A. Klötzli: Vegetation of the earth. Springer Spectrum, Berlin / Heidelberg 2014, ISBN 978-3-642-41949-2 . Pp. 74-78
  6. ↑ Altitudes Spektrum.de
  7. ^ Social Ecology Working Paper 58, Karl Heinz Erb: The influence of the above-ground standing crop and turnover in Austria by human society aau.at
  8. ↑ a b [1] Gustav Wendelberger : About the independence of the planar stage
  9. ^ W. Kilian, F. Müller, F. Starlinger: The forestry growth areas of Austria. A natural area structure according to forest ecological aspects. , Online pdf version , Federal Forest Research Institute , Vienna 1994, ISSN  0374-9037 , p. 10.
  10. ↑ Heinz Ellenberg : Vegetation of Central Europe with the Alps in an ecological, dynamic and historical perspective. 5th, heavily changed and improved edition. Ulmer, Stuttgart 1996, ISBN 3-8001-2696-6 .
  11. ↑ Reiner Suck, Michael Bushart, Gerhard Hofmann and Lothar Schröder: Map of the Potential Natural Vegetation of Germany, Volume I, Basic Units. BfN scripts 348, Federal Agency for Nature Conservation, Bonn / Bad Godesberg 2014, ISBN 978-3-89624-083-5 .
  12. ↑ Josef Schmithüsen (Ed.): Atlas for Biogeography. Meyer's large physical world atlas, vol. 3., Bibliographisches Institut, Mannheim, Vienna, Zurich 1976, ISBN 3-411-00303-0 . P. 31.
  13. ↑ Brigitta Verschbamer (Head): Excursion abroad Tenerife - April 29th. until 6.5. 2016 , Institute for Botany, University of Innsbruck , online excursion report , accessed on August 3, 2020, pp. 20–26, 58, 69.
  14. ↑ The altitude levels of the Andes geohilfe.de
  15. ↑ Vegetation areas of the earth . In: link.springer.com, accessed on August 26, 2020, p. 412 (= p. 8 in the pdf).
  16. ↑ Josef Schmithüsen (Ed.): Atlas for Biogeography. Meyer's large physical world atlas, vol. 3., Bibliographisches Institut, Mannheim, Vienna, Zurich 1976, ISBN 3-411-00303-0 . P. 23.
  17. ↑ Georg Grabherr: Color Atlas of Ecosystems of the Earth. Ulmer, Stuttgart 1997, ISBN 3-8001-3489-6 . Pp. 165-166.
  18. ↑ Harold DeWitt Roberts and Rhoda N. Roberts: Colorado Wild Flowers. Denver Museum of Natural History Popular Series # 8, 1953, p. 3 (converted from feet to meters, rounded to match the drawing)
  19. ↑ Altitude levels and forest community
  20. ↑ Wolfgang Frey , Rainer Lösch : Geobotany : Plant and Vegetation in Space and Time , ISBN 978-3-8274-2335-1 , Page 478 limited preview in the Google book search