Altitude level (ecology)

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Illustration by A. von Humboldt and A. Bonpland from Ideas for a Geography of Plants together with a natural painting of the tropical countries , Paris 1805
The clearest indication of the existence of different levels of vegetation in a mountain range is the contrast between the mountain forest and the treeless high areas (view of the Sarek from Laitaure , Swedish Lapland)

In ecology , geobotany and biogeography, the climatically conditioned areas of similar natural vegetation in mountains , the extent and boundaries of which are determined according to the height above sea level, are called altitude levels (also high altitude belts , mountain or vegetation levels ) . With increasing altitude, the site conditions for plants become more and more extreme and require appropriate adjustments that lead to a typical, vertical sequence of different plant formations. Basically, the gradation of the mountain vegetation shows great similarities with the global vegetation zones . Since the plant cover is sufficient as a bio-indicator , the animal world only plays a subordinate role. Analogous to the global climatic and vegetation zones, climatic changes lead to shifts in the altitude belt, which in turn affects the habitats of animals.

In the humid mountains of the cool-temperate climate zone , the altitude zoning begins with the deciduous forest of the planar lowlands and the colline hill step , which is increasingly interspersed with coniferous trees in the montane low mountain range upwards , to finally form the upper tree line as a mountain coniferous forest , which forms the transition into the alpine High mountain steps marked. The "battle zone" of the forest up to the tree line is usually referred to as the subalpine level . (Such transition zones between the steps usually only cover a few dozen meters in altitude.) Above is the tree-free, dwarf shrub and grass-covered mat region of the alpine highlands, which ends in the almost vegetation-free nival rock and ice region .

The aforementioned orographic designations of the altitude levels (planar, collin, montane, alpine, nival) - which are further subdivided depending on the mountain range (submontane, high montane, upper montane, etc.) and are generally used for humid mountains in the temperate zone - are used by many authors used in whole or in part for mountains in other climatic zones . However, a direct comparison between the classifications of different mountains is only possible to a limited extent due to the many differences. For this reason, some authors prefer to use different or their own nomenclatures . If the limits of an altitude level are only given one meter in each case in the literature , this is to be understood as an average value, since the actual conditions - especially on the north and south sides of the mountains - sometimes deviate considerably.

The higher a mountain range, the greater the difference between the mountain flora and the zonal vegetation of the surroundings with increasing altitude. The altitude levels, which are clearly shaped by the mountain climate, are therefore also called extrazonal . In addition, there are a number of azonal ecotopes whose vegetation is also characterized by non-climatic site conditions of the soil (rocks, thin humus layer, erosion, etc.) or the water balance (waterlogging, groundwater level, still and flowing water).

If one only considers the climatological differences, the altitude classification is called climatic level or climatic altitude zone .

Valley, middle and high altitudes

In the high mountains of the temperate zone it is obvious and therefore trivial that the vegetation differs depending on the altitude. Without going into more detail about the characteristics of altitude levels, the three-part division of low (valley), middle and high is generally understandable. The boundary between the middle and high elevations of all humid mountains is the (upper) tree line . A general limit for all mountains worldwide results from the respective frost or snow line .

History of science

The scientific description of global geo and local elevation zoning began with the research trips of the early modern era. Conrad Gessner , who became famous in the middle of the 16th century for his description of the zoning of Mount Pilatus on Lake Lucerne (Switzerland), was the first to rank among the altitude levels . With the structure of the Andes , Alexander von Humboldt set decisive standards for later step models. Major contributions to the 20th century came from Carl Troll .

Climatic basics

A tepui in Venezuela as an example of a “heavenly island” with strongly emphasized elevations

The interplay of increasing heat radiation , decreasing air pressure and the corresponding negative temperature gradient in the lowest layer of the atmosphere basically causes temperatures to decrease by around 0.4 to 0.7 ° C per 100 meters with increasing altitude. Isolated mountain peaks are always cooler than mountain ranges or high plateaus at the same height .

In this respect, the sea level has a significant influence on the annual temperature change and thus on the vegetation period of the plants, which becomes shorter and shorter towards the summit (on average 6 to 7 days per 100 meters). In connection with the amount and distribution of the precipitation results the humidity or aridity of the considered space.

Since mountains also have an increasing influence on the atmospheric air currents - and thus on the weather - depending on the altitude , the moisture conditions there are often different than in the flat surrounding areas (see, for example, inclined rain ). These climatic factors essentially determine the biological communities ( biocenoses ) that occur . The climatic and ecological differences are particularly pronounced in the case of high island mountains , which are also known as " Sky Islands ".

There are comparable global climatic zones with similar plant formations to the high-altitude climates. On closer inspection, however, there are clear differences (see #Comparison of altitude levels, climate and vegetation zones )

Shift due to climate change

A comparison with the reports by Alexander von Humboldt and Aimé Bonpland at the Antisana shows that the vegetation in 2019 was over 200 meters higher than it was around 1800. In recent decades, due to global warming, the vegetation levels of the Andes have increased ten to twelve meters per decade moved up.

This tendency can also be observed in the temperate latitudes: While in Westphalia in 1981 an upper limit of 200 m was specified for the lowest low mountain range, the State Forest and Wood Office of North Rhine-Westphalia drew the limit at 300 m in 2011.

Comparison of altitude levels, climatic and vegetation zones

At first glance, the sequence and shape of the plant cover from the plain to the summit regions show great similarities with the global vegetation zones , the climate of which depends on the geographical latitude from the equator to the poles. These zonal vegetation types are relatively uniform on a global scale and can usually be described with very large-scale ecosystem types or biomes . The conditions of different mountains, on the other hand, show clear differences due to special climatic differences and their own ( isolated ) tribal history of the species inventory , which cause the deviations. While a global distinction is made between boreal coniferous forest, hemiboreal transitional mixed forest and nemoral deciduous forest, in the mountains the specific plant communities - such as collin oak-hornbeam forest , submontane beech forest , low- montane fir-beech forest and high-montane spruce-fir forest - must be used.

Walter and Breckle speak of the global zonobiomes in contrast to the orobiomes of the mountains.


The further apart climatically comparable zono- and orobiomes are, the greater are the following differences:

Accordingly, the differences between the tundra of the arctic lowlands and the mountain tundra of southern Norway at 1000 to 1600 m are slight, while the climatically comparable páramo vegetation of the tropical Andes at 3800 to 4700 m has completely different plant formations and plant communities .

The height of a mountain range and the slope also have an influence on:

Models and names

The further the mountains are apart, the greater the differences! For this reason, in addition to the established, orographic terms (planar, kollin, montan, alpine, nival, etc.), depending on the author and professional orientation, particularly for mountains outside the temperate zones, completely different terms are used or defined differently than in other models .

While the high mountain levels above the upper (thermal) tree line are comparable to a certain extent, there is a risk of confusion with the other terms if a level is not considered in the context of the entire model. Above all, the use of the term subtropical altitude level for the second level of tropical mountains (instead of the planar level of subtropical mountains) and two different definitions for the subalpine altitude level are criticized .

Examples of height level models

Altitude level classification of the Alps

The “classic” elevation classification of the (northern) Alps or the Central European mountains has become established, which can be derived from the orographic or geomorphological conditions (plains, hills, low mountain ranges, high mountain ranges). The names come from traditional alpine research . In order to do justice to the significantly different altitude zones of mountains, for example Mediterranean, arid (forest-free) or tropical climates, as well as in foreign-language literature, there are sometimes completely different names and sequences.

Alps and low mountain ranges in Germany and Austria

Even within the Alps, the altitude levels are at slightly different altitudes depending on latitude and continentality . What they have in common is the typical, albeit regionally specific, sequence that can be determined from general indicators.

The following is the information for the Eastern Alps and the North and West German low mountain ranges :

Altitude level General
Altitude up to
Description (vegetation only related to the Alps) 1 Temperatures
(° C) 7
Technical term translation Alps 1 Funded 2 annual mean coldest month
planar Lowland level Lowlands
valleys 7
<300 <100 Low-lying areas with the usual average temperatures of the climatic zone, very diverse, vegetation: deciduous forests, today extensive anthropogenic cultural landscapes > 11 1/10
Kollin Hill country -
300-800 100-300 Upper limit of oaks and viticulture ; European beech forest , oak forest, oak-hornbeam forest ; very diverse, widely influenced by the cultural landscape
submontane deepest low mountain range 700-1000 300-500 Beech forest with increasing silver fir , spruce-fir-beech forest , spruce-fir forest , Europe-wide forestry spruce substitute crops, upper limit of fruit growing in favored locations; in the Alps transition zone from ecumenism to sub-ecumenism 8 8/11 0 / −3
(deep) montane 3
Low mountain range
( Montanstufe )
Middle layers 800-1200 500-600 already lower average temperature, but still mild due to cold air runoff, in hollows and valleys, on the other hand, more continental with a clear risk of frost ( cold air lakes ), common beech significantly pushed back, increasingly coniferous trees such as spruce , a clearly visible change in azonal vegetation units ; in the Alps upper limit of ecumenism to sub-ecumenism (very occasionally still farms today: upper limit of wheat and rye )
middle montan  / upper montan 3 1000-1400 600-800 Summit region and subecumen of the low mountain range; Local transition zone in the Alps from low to high montane
high montane 1300-1850 800-1000 Upper limit of the deciduous forest , mainly coniferous forests ; only seasonally habitable: Mittelalmen (early summer and late summer pastures , early mountain mowing )
subalpine deepest high mountain range High altitudes 1500-2500 1000-1100 "Battle zone" of the forest between the forest and tree line, the lower limit is marked by the upper limit of distribution of red beech and fir, as well as sycamore and red pines : red beech only very sporadically in favorable locations (e.g. western Alps), otherwise similar to boreal forests Siberia with spruce, larch , Swiss stone pine 4 , cripple growth forms and dwarf forms ( Nana varieties , such as pine fields ), deep glacier tongues ; Hochalm region (high summer pasture for cattle and horses) 4/7 −4 / −6
alpine High mountain range 2000-3000 > 1100 generally forest-free mountain tundra , meadows , alpine dwarf shrub heaths , lawns , perennial vegetation , cushion plants , above only lichen and moss 6 , consumption area of ​​glaciers ; Only herds of sheep and goats that have moved freely are managed <4 <−7
nival > 3000 Border of closed vegetation of the alpine peaks; Standing rock, largely snow-covered anecumens , nutrient area for glaciers ; Cryoplankton , in the snow-free Nunatak corridors 6 <0
1Values ​​and description apply to the Eastern Alps . For the Pannonian-Illyrian eastern roofing ( foreland in the east and south-east ), the values ​​are in the area of ​​the German low mountain range, in the southern Alps and southern western Alps even lower, the forest and snow line are significantly higher within the Alps , for the Maritime Alps see Mediterranean area below . Values ​​for the Carpathians largely the same.
2 Values ​​up to the upper montane level for North Rhine-Westphalia and above that up to the alpine level for the Harz
3In the absence of a high- montane zone in low mountain ranges, montan / upper montan applies , otherwise low / medium / high montan , with some authors also lower / upper montan for the entire montane level.
4thThis level is called the deep subalpine level , above it the high subalpine level : still with pure larch-stone pine forest .
5Also as a fine division: lower alpine for alpine lawn and dwarf shrub heaths , upper alpine for cushion plants, mosses and lichens
6thAs an outsourcing subnival: upper limit of vascular plants
7thThe actual upper limit can be significantly higher regionally: Juf / Graubünden (2126 m) and Trepalle / Sondrio are considered to be the highest permanently inhabited settlements in the Alps
8th Annual mean and monthly mean of the coldest month of the year, for the Eurosiberian zone (excluding the Mediterranean region)

Mediterranean zone

Transect of Mediterranean altitudes in the central main ridge of the Orjen

For the Mediterranean regions , which are characterized by many endemic plants and species-rich biocenoses of subtropical hard - leaved vegetation , park-like nemoral coniferous forest , shrub adapted to drought and dry grass formations rich in geophytes , a special terminology has become established.

In the classic Mediterranean area, between north-Mediterranean transition zones with lower Mediterranean and upper Alpine elevation zoning (e.g. Southern and Maritime Alps), Mediterranean zoning (e.g. Pindos , South Apennines , Sierra Nevada ) with eumediterranean or thermomediterranean lowest Level , as well as the dry mountains of North Africa ( Atlas ) and the Near East ( Lebanon , Taurus ) with a xeromediterranean lower level .
On the other hand, a distinction is made between western, central and eastern Mediterranean elevation zoning in terms of flora history, as the individual mountains, due to a different flora inventory, also develop extremely contrasting levels of altitude. The typical arid thorn cushion stage (also called Mediterranean thorn cushion rock heather with Acantholimon and Astracantha ) occurs in the Atlas, the Sierra Nevada, Taurus, southern Italy and Crete, but is absent, for example, in the Greek Pindos, the Dinaric Alps or the Apennines and Corsica . The thorn cushion step is typically cryo-Mediterranean and occurs, for example, on Crete between 1500 and 2456 meters, in the Taurus between 1700 and 2700 meters and the High Atlas between 2400 and 3500 meters.

The tree line in Mediterranean mountains is always formed by drought-resistant conifers ; These typical oromediterranean dry forests at the tree line are in the southeast Dinarides of the endemic xero-basophilic snake-skin pine , in the Pindos also with the Greek fir , in the Sierra Nevada by the Spanish fir and in the Taurus and Atlas by the Cilician fir , Numidian Fir , Lebanon cedar and Atlas cedar .

As an example of the Mediterranean elevation , the Orjen is illustrated in the littoral (coastal) south-east Dinarides according to Sergeevič & Grebenščikov. (Note: The translation into the comparable orographic levels may vary depending on the author and the mountain range.)

Mediterranean model orographic
High altitudes description
(hard foliage )
planar collin 0-400 Hard-leaf vegetation with holm oak and olive tree . Laurel - oleander bush formationin damp places.
(Hartlaub mixed foliage)
submontane 400-1100 semi-evergreen oak forest with Macedonian oak ( Quercus trojana ) and oriental hornbeam ( Carpinus orientalis ). In oaks - and Balkan oak forests ( Quercus frainetto ). In damp and shady locations, chestnuts - downy oak forests , as well as warmth- loving hop beech and downy oak forests. The pioneer species of silver fir and tree hazel grow on dry and sunny log heaps .
(deciduous forest level)
montane 1100-1450 Warmth-loving beech forest with fir trees. On rocky areas, drought-loving snakeskin pine and Dinaric karst block dump fir forests, some with Crimean peony . For the warmth-loving beech forests, not only warmth- loving blue grasses ( Sesleria autumnalis ) but also hygrophilic plants such as the Pleasant Columbine are typical.
ancient Mediterranean
(forest boundary)
subalpine 1450-1700 Red beech, snake skin pine and Greek maple at the tree line . Above that, dry juniper heaths and Sesleria robusta lawn communities with many endemic species (e.g. Orjen iris , Dinaric Columbine Viola chelmea ) are characterized. On coarse-block pebbles and rocks, shrub communities with chasmophytic limestone crevices (e.g. mountain savory , brown-stemmed striped fern , Neumayer jug ​​fruit ( Amphoricarpos neumayerianus )).
(highland steppe)
alpine 1700-1900 A “real” cold Mediterranean climate level has not developed in the highest mountains on the Dinaric coast. Due to high winter precipitation and stormy Bora summit winds, small snow valleys with Greek-Anatolian, Iranian-Turanian and Armeno-Tibetan xerophytes develop under extensive snow layers . The latter include the semi-desert snow valleys with predominant onion monocotyledons, which are adapted to rocky soils, dry summers and hurricane-like Bora and Scirocco winds.
Further examples
  • Corsica: up to 150 m (in sunny locations; in shadows up to 100 m or even absent): thermo-Mediterranean level ; up to 900 m (Schattlagen: up to 600–700): Meso-Mediterranean zone ; 800–1000 to 1200–1350 m (Schattlagen: 500–700 to 900–1000 m): supramediterranean zone ; 1300 to 1800 m (Schattlagen: 900–1000 to 1600 m): montane zone ; 1700–1800 to 2200 m (only in sunny positions ; absent in shady positions): cryo-Mediterranean zone ; 1400–1600 to 2100 m (replacing the cryo-Mediterranean zone in Schattlagen): subalpine zone ; over 2100 m: alpine level .
  • Iberian Peninsula (annual mean temperature and fluctuation or minimum temperature): thermomediterranean over 16 ° (+ 30 ° / + 10 °); Meso-Mediterranean : 16 ° –12 ° (+ 30 ° / + 0 °); oromediterranean: 8 ° –4 ° (min. −3 ° / −6 °); cryo-Mediterranean below 4 ° (min below −6 °). These criteria are also used as a basis for the height zoning, which fluctuates greatly due to the Atlantic-Mediterranean mixed location.

Other parts of the world

In principle, the higher the mountain range, the more humid the climate and the closer a mountain range is to the equator, the greater the number of vegetation levels. Accordingly, the highest mountains in the polar regions - such as Mount Vinson in Antarctica (approx. 5000 m) and Gunnbjørn Fjeld in Greenland (approx. 3700 m) - are completely in the glacier region of the nival level or the polar zonal climate, while for example Kinabalu on Borneo or the Andes-east side of Venezuela in the always humid tropics each seven (large-scale) levels can be described. The closely spaced gradation of tropical mountains inevitably leads to an enormous biological diversity per unit area, so that almost all so-called megadiversity centers on earth with more than 5,000 vascular plant species on 10,000 km² can be found there.

In the southern hemisphere , due to the greater proximity to the seas, the altitudes are generally more oceanic than in the northern hemisphere , where there are also many continental ones.

To the

The classic Latin American, thermal elevations of the Andes for the tropical latitudes: Tierra Caliente (“hot land”) 0–1000 m, Tierra Templada (“temperate land”) 1000–2000 m, Tierra Fria (“cool land”) 2000–3500 m, Tierra Helada ("cold land") from the tree line, Tierra Nevada ("snow land ") from the snow line at about 5000 m

Elevation levels to Vidal : Chala (west, Pacific coast) 0–500 m, Omagua (east, Amazonia) 80–400 m, Rupa-Rupa 400–1000 m (east side), Lomas (west side) 450–600 m, and Yunga 1000– 2300 m, Quechua 2300–3500 m, Suni , Jalca or Sallqa 3500–4000 m, Puna 4000–4800 m, Janca over 4800 m.

Hindu Kush

For the Hindu Kush - as for many mountains - different altitude levels have to be formed depending on the side: The north (N) is continental dry, the south (S) is under the influence of monsoons; according to Breckle, 2004:

  • Valley area N <1400, S <1100; Deciduous forest levels N 1400–2000, S 1000–2300; Coniferous forest levels N 2000–2800, S 2200–3000; Timber line N is not recognizable, S 3000-3150; Subalpine level N 2800-3600, S 3000-3500; Alpine Level N 3600-4200, S 3500-4300; Subnival stage N 4200-4800, S 4300-5200; Snow line N 4800–5200, pp. 5200–5400

See also


  • Conradin Burga , Frank Klötzli and Georg Grabherr (eds.): Mountains of the earth - landscape, climate, flora. Ulmer, Stuttgart 2004, ISBN 3-8001-4165-5 .
  • P. Ozenda: The vegetation of the Alps in the European mountain area. Gustav Fischer Verlag, Stuttgart / New York 1988, ISBN 3-437-20394-0 . (with a detailed attempt to parallelize the altitude levels of the Alpine region and the neighboring mountains)
  • Friedrich Ratzel : Height limits and height belts. 1889. (interesting for the history of research)

Individual evidence

  1. "The sheet is folded in the cover to ideas for a geography of plants ... from 1807 glued in ... Designed by A. von Humboldt, drawn in Paris in 1805 by Schönberger and Turpin" ( )
  2. a b c 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. 295-302 (general), -311 (extra tropics), -319 (subtropics), -327 (tropics).
  3. a b c d e f Cf. Burga, Klötzli and Grabherr (2004), pp. 31–36.
  4. Hannes Obermair , Volker Stamm : Alpine economy in high and low altitudes - the example of Tyrol in the late Middle Ages and early modern times . In: Luigi Lorenzetti, Yann Decorzant, Anne-Lise Head-König (eds.): Relire l'altitude: la terre et ses usages. Suisse et espaces avoisinants, XIIe – XXIe siècles . Éditions Alphil-Presses universitaires suisses, Neuchâtel 2019, ISBN 978-2-88930-206-2 , p. 29-56 ( ).
  5. ^ Richard Pott: General Geobotany. Berlin / Heidelberg 2005, ISBN 3-540-23058-0 .
  6. ^ Heinz Veit: The Alps - Geoecology and Landscape Development. Ulmer, Stuttgart 2002, ISBN 3-8252-2327-2 .
  7. a b c Jörg S. Pfadenhauer and Frank A. Klötzli: Vegetation of the earth. Springer Spectrum, Berlin / Heidelberg 2014, ISBN 978-3-642-41949-2 . Pp. 73-78, 337-343.
  8. a b Dieter Heinrich, Manfred Hergt: Atlas for ecology. Deutscher Taschenbuch Verlag, Munich 1990, ISBN 3-423-03228-6 . P. 95.
  9. "Humboldt's primary plant data above tree line were mostly collected on Mt. Antisana, not Chimborazo, which allows a comparison with current records. ... resurvey at Mt. Antisana revealed a 215- to 266-m altitudinal shift over 215 y. This estimate is about twice lower than previous estimates for the region but is consistent with the 10- to 12-m / decade upslope range shift observed worldwide. ”From abstract by Pierre Moret u. a .: Humboldt's Tableau Physique revisited ; How Humboldt's vegetation zones have changed @, May 27, 2019, accessed May 30, 2019
  10. L. Franzisket (Ed.): Treatises from the State Museum for Natural History in Münster in Westphalia, 3rd year 1981, No. 4 . In:, Münster, accessed on May 21, 2020, p. 28.
  11. Work instructions for carrying out medium-term operational planning, Annex 01-13 (survey characteristics) . In:, Münster, July 1, 2011, accessed on May 25, 2020, p. 5.
  12. 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 .
  13. ^ W. Kilian, F. Müller, F. Starlinger: The forestry growth areas of Austria . Ed .: Federal Forest Research Institute. 1994, ISSN  0374-9037 , p. 10 ff . ( Online ( Memento of October 25, 2012 in the Internet Archive ) [accessed on July 20, 2016]). The forest growth areas of Austria ( Memento of the original from October 25, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot /
  14. Landesbetrieb Wald und Holz Nordrhein-Westfalen: Work instructions for the implementation of medium-term operational planning, Annex 01-13 (survey characteristics) . In:, Münster, July 1, 2011, accessed on May 25, 2020, p. 5.
  15. Valuable habitats in the Harz National Park at, accessed on July 4, 2020 (slightly adjusted).
  16. a b Information about Salvador Rivas-Martínez : Les Étages bioclimatiques de la Végétation de la Péninsule Iibérique. In: Actas III Congr. Óptima. Anal Jard. Bot. Madrid. 37 (2), 1981, section Étages de Vegetation et Étages bioclimatiques. P. 254 ff, especially table p. 256/57 (French article, pp. 251–268 with a detailed discussion of the individual zones, (PDF) there p. 6)
  17. ^ Jacques Blondel 2010: The Mediterranean Region: Biological diversity in Space and Time . Oxford University press. ISBN 978-0-19-955798-1 . Here p. 99ff
  18. An overview is provided by: Herbert Reisigl: Vegetation Landscapes and Flora of the Mediterranean Area . In: Robert Hofrichter (Ed.): The Mediterranean. Fauna, flora, ecology . Series The Mediterranean . Volume I: General Part . Spektrum Akademischer Verlag, 2001, ISBN 978-3-8274-1050-4 , 4th, pp. 169-207 .
  19. ^ Pavle Cikovac: Sociology and site-dependent distribution of fir-rich forests in the Orjen Mountains (Montenegro). University of Munich, Munich 2002 (diploma thesis) .
  20. ^ Oleg Polunin: Flowers of Greece and the Balkans. Oxford University Press, Oxford 1980, ISBN 0-19-281998-4 .
  21. ^ Ivo Horvat , Vjekoslav Glavač, Heinz Ellenberg: Vegetation Southeast Europe. Fischer, Stuttgart 1974, ISBN 3-437-30168-3 .
  22. Carsten Kemp: Distribution and ecology of the thorn upholstered corridors of Crete. September 2002 (excursion guide for Crete).
  23. Oleg Sergeevič Grebenščikov: The Vegetation of the Kotor Bay Seabord (Montenegro, Yugoslavia) and some comparative studies with the Caucasian seaboard of the Black Sea. In: Bjull Mskovsk. Obsc. Isp. Prir., Otd. Biol. 65, pp. 99-108, 1960.
  24. Daniel Jean Monod, Jacques Gamisans: Flora Corsica. Edisud, Aix-en-Provence 2007, ISBN 978-2-7449-0662-6 .
  25. traditional classification, according to W. Zech, G. Hintermaier-Erhard: Soils of the world - A picture atlas . Heidelberg 2002, p. 98 .
  26. Javier Pulgar Vidal: Geografía del Perú; Las Ocho Regiones Naturales del Perú . Edit. Universo SA, Lima 1979.
  27. Siegmar-W. Breckle: flora, vegetation and ecology of the alpine-nival level of the Hindu Kush (Afghanistan) . In: S.-W. Breckle, Birgit Schweizer, A. Fangmeier (Ed.): Results of worldwide ecological studies. Proceedings of the 2nd Symposium of the AFW Schimper Foundation . Verlag Günter Heimbach, Stuttgart 2004, ISBN 3-9805730-2-8 , Ecology Tab. 3, p. 112 .