A biogeographic realm or ecozone is the broadest
biogeographic Biogeography is the study of the distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological communities often vary in a regular fashion along geograp ...

division of Earth's land surface, based on distributional patterns of
terrestrial Terrestrial refers to things related to land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable over geologic time frames) and consists main ...
organisms. They are subdivided into
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including h ...
s, which are classified based on their
biome A biome is a collection of plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respi ...
s or habitat types. The realms delineate the large areas of Earth's surface within which organisms have been evolving in relative isolation over long periods of time, separated from one another by geographic features, such as
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
s, broad
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

s, or high
mountain range A mountain range is a series of mountains ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, us ...

mountain range
s, that constitute barriers to migration. As such, biogeographic realm designations are used to indicate general groupings of organisms based on their shared biogeography. Biogeographic realms correspond to the floristic kingdoms of
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

or zoogeographic regions of
zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological class ...
. Biogeographic realms are characterized by the evolutionary history of the organisms they contain. They are distinct from biomes, also known as major habitat types, which are divisions of the Earth's surface based on ''life form'', or the adaptation of animals, fungi, micro-organisms and plants to climatic,
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

, and other conditions. Biomes are characterized by similar
climax vegetation In scientific ecology, climax community or climatic climax community is a historic term for a community A community is a social unit The term "level of analysis" is used in the social sciences to point to the location, size, or scale of a rese ...
. Each realm may include a number of different biomes. A
tropical moist broadleaf forest Tropical and subtropical moist forest (TSMF), also known as tropical moist forest, is a tropical and subtropical forest habitat (ecology), habitat type defined by the World Wide Fund for Nature. The habitat type is sometimes known as jungle. D ...
in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by animals, fungi, micro-organisms and plants with very different evolutionary histories. The patterns of distribution of living organisms in the world's biogeographic realms were shaped by the process of
plate tectonics Plate tectonics (from the la, label=Late Latin Late Latin ( la, Latinitas serior) is the scholarly name for the written Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. L ...
, which has redistributed the world's land masses over geological history.

Concept history

The "biogeographic realms" of Udvardy (1975) were defined based on taxonomic composition. The rank corresponds more or less to the
floristic kingdom A phytochorion, in phytogeography Phytogeography (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in South ...
s and
zoogeographic region Zoogeography is the branch of the science of biogeography that is concerned with geographic distribution (present and past) of animal species. As a multifaceted field of study, zoogeography incorporates methods of molecular biology, genetics, mor ...
s. The usage of the term "ecozone" is more variable. It was used originally in
stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...

(Vella 1962, Hedberg 1971). In Canadian literature, the term was used by Wiken (1986) in macro level
land classification Regionalisation is the tendency to form Decentralization, decentralised regions. Regionalisation or land classification can be observed in various disciplines: *In agriculture, see Agricultural Land Classification. *In biogeography, see Biogeogra ...
, with geographic criteria (see
Ecozones of Canada Canada is divided into 15 ecozones, forming the country's first level of ecological land classification within the Ecological Land Classification framework adopted in 2017. They represent areas of the earth's surface representative of large and ve ...
) (Wicken 1986, Scott 1995). Later, Schültz (1988) would use it with ecological and physiognomical criteria, in a way similar to the concept of
biome A biome is a collection of plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respi ...
. In the
Global 200 The Global 200 is the list of ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an and geographically defined area that is smaller than a , which in turn is smaller than a . Ecoregions cover relatively large areas o ...
/WWF scheme (Olson & Dinerstein 1998), originally the term "biogeographic realm" in Udvardy sense was used. However, in a scheme of
BBC The British Broadcasting Corporation (BBC) is a public service broadcaster, headquartered at Broadcasting House in Westminster, London. It is the world's oldest national broadcaster, and the largest broadcasting, broadcaster in the world by ...

(n.d.), it was replaced by the term "ecozone".

Terrestrial biogeographic realms

Udvardy (1975) biogeographic realms

WWF / Global 200 biogeographic realms (BBC "ecozones")

World Wildlife Fund In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the worl ...
scheme (Olson & Dinerstein 1998, Olson et al. 2001) is broadly similar to
Miklos Udvardy Miklos Dezso Ferenc Udvardy (March 23, 1919 – January 27, 1998) was a Hungarian biologist A biologist is a professional who has specialized knowledge in the field of biology Biology is the natural science that studies life and living ...
's (1975) system, the chief difference being the delineation of the Australasian realm relative to the Antarctic, Oceanic, and Indomalayan realms. In the WWF system, the Australasia realm includes
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Tasmania Tasmania (), abbreviated as TAS, is an island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atol ...
, the islands of
Wallacea Wallacea is a biogeographical Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of bio ...

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign ...

New Guinea
, the East Melanesian Islands, New Caledonia, and New Zealand. Udvardy's Australian realm includes only Australia and Tasmania; he places
Wallacea Wallacea is a biogeographical Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of bio ...

in the Indomalayan Realm, New Guinea, New Caledonia, and East Melanesia in the Oceanian Realm, and New Zealand in the Antarctic Realm. The Palearctic realm, Palearctic and Nearctic realm, Nearctic are sometimes grouped into the Holarctic realm.

Morrone (2015) biogeographic kingdoms

Following the nomenclatural conventions set out in the International Code of Area Nomenclature, Morrone (2015) defined the next biogeographic kingdoms (or realms) and regions: * Holarctic kingdom Heilprin (1887) ** Nearctic region Sclater (1858) ** Palearctic region Sclater (1858) * Holotropical kingdom Rapoport (1968) ** Neotropical region Sclater (1858) ** Ethiopian region Sclater (1858) ** Oriental region Wallace (1876) * Austral kingdom Engler (1899) ** Cape region Grisebach (1872) ** Andean region Engler (1882) ** Australian region Sclater (1858) ** Antarctic region Grisebach (1872) * Transition zones: ** Mexican transition zone (Nearctic–Neotropical transition) ** Saharo-Arabian transition zone (Palearctic–Ethiopian transition) ** Chinese transition zone (Palearctic–Oriental transition zone transition) ** Indo-Malayan, Indonesian or Wallace's transition zone (Oriental–Australian transition) ** South American transition zone (Neotropical–Andean transition)

Freshwater biogeographic realms

The applicability of Udvardy (1975) scheme to most freshwater taxa is unresolved (Abell et al. 2008). The drainage basins of the principal oceans and seas of the world are marked by continental divides. The grey areas are endorheic basins that do not drain to the ocean.

Marine biogeographic realms

According to Briggs (1995) and Morrone (2009): According to the WWF scheme (Spalding, 2007):

See also

*Cosmopolitan distribution *Ecotone *Phytochorion and World Geographical Scheme for Recording Plant Distributions, used in botany


* Abell, R., M. Thieme, C. Revenga, M. Bryer, M. Kottelat, N. Bogutskaya, B. Coad, N. Mandrak, S. Contreras-Balderas, W. Bussing, M. L. J. Stiassny, P. Skelton, G. R. Allen, P. Unmack, A. Naseka, R. Ng, N. Sindorf, J. Robertson, E. Armijo, J. Higgins, T. J. Heibel, E. Wikramanayake, D. Olson, H. L. Lopez, R. E. d. Reis, J. G. Lundberg, M. H. Sabaj Perez, and P. Petry. (2008). Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. ''BioScience'' 58:403-414

* * Briggs, J.C. (1995). ''Global Biogeography''. Amsterdam: Elsevier. * Morrone, J. J. (2009). ''Evolutionary biogeography, an integrative approach with case studies''. Columbia University Press, New York

* Morrone, J. J. (2015). Biogeographical regionalisation of the world: a reappraisal. ''Australian Systematic Botany'' 28: 81-90

* Olson, D. M. & E. Dinerstein (1998). The Global 200: A representation approach to conserving the Earth’s most biologically valuable ecoregions. ''Conservation Biol.'' 12:502–515

* Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C., D'Amico, J. A., Itoua, I., Strand, H. E., Morrison, J. C., Loucks, C. J., Allnutt, T. F., Ricketts, T. H., Kura, Y., Lamoreux, J. F., Wettengel, W. W., Hedao, P., Kassem, K. R. (2001). Terrestrial ecoregions of the world: a new map of life on Earth. ''Bioscience'' 51(11):933-938

* Schültz, J. ''Die Ökozonen der Erde'', 1st ed., Ulmer, Stuttgart, Germany, 1988, 488 pp.; 2nd ed., 1995, 535 pp.; 3rd ed., 2002. Transl.: ''The Ecozones of the World: The Ecological Divisions of the Geosphere''. Berlin: Springer-Verlag, 1995; 2nd ed., 2005

* Scott, G. 1995. Canada's vegetation: a world perspective, p.

* Spalding, M. D. et al. (2007). Marine ecoregions of the world: a bioregionalization of coastal and shelf areas. ''BioScience'' 57: 573-583

* Udvardy, M. D. F. (1975). ''A classification of the biogeographical provinces of the world.'' IUCN Occasional Paper no. 18. Morges, Switzerland: IUCN

* Wicken, E. B. 1986. ''Terrestrial ecozones of Canada'' / ''Écozones terrestres du Canada''. Environment Canada. Ecological Land Classification Series No. 19. Lands Directorate, Ottawa. 26 pp.

{{Biomes Biogeography Habitat Biogeographic realms,