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42-452: The Antarctic realm is one of eight terrestrial biogeographic realms . The ecosystem includes Antarctica and several island groups in the southern Atlantic and Indian oceans. The continent of Antarctica is so cold that it has supported only 2 vascular plants for millions of years, and its flora presently consists of around 250 lichens , 100 mosses , 25–30 liverworts , and around 700 terrestrial and aquatic algal species, which live on

84-415: A given ecoregion are more similar to each other than to those of surrounding ecoregions and together form a conservation unit. Freshwater systems include rivers , streams , lakes , and wetlands . Freshwater ecoregions are distinct from terrestrial ecoregions, which identify biotic communities of the land, and marine ecoregions, which are biotic communities of the oceans. A map of Freshwater Ecoregions of

126-469: A holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey 's work for the U.S. Forest Service, which uses a hierarchical classification that first divides land areas into very large regions based on climatic factors, and subdivides these regions, based first on dominant potential vegetation, and then by geomorphology and soil characteristics. The weight-of-evidence approach

168-517: A set of ecoregions identified by WWF whose conservation would achieve the goal of saving a broad diversity of the Earth's ecosystems, includes a number of areas highlighted for their freshwater biodiversity values. The Global 200 preceded Freshwater Ecoregions of the World and incorporated information from regional freshwater ecoregional assessments that had been completed at that time. Sources related to

210-407: A web application developed by Resolve and Google Earth Engine. An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik (2004) elaborates on this by defining ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in

252-527: Is also known as "ecozone", although that term may also refer to ecoregions. The realms delineate large areas of Earth's surface within which organisms have evolved in relative isolation over long periods of time, separated by geographic features, such as oceans , broad deserts , or high mountain ranges , that constitute natural 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

294-426: Is analogous to that used for terrestrial ecoregions. Major habitat types are identified: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench). These correspond to the terrestrial biomes . The Global 200 classification of marine ecoregions is not developed to the same level of detail and comprehensiveness as that of

336-622: Is exemplified by James Omernik's work for the United States Environmental Protection Agency , subsequently adopted (with modification) for North America by the Commission for Environmental Cooperation . The intended purpose of ecoregion delineation may affect the method used. For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, and place a greater emphasis than

378-526: Is optimal for all taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries rarely form abrupt edges; rather, ecotones and mosaic habitats bound them. Thirdly, most ecoregions contain habitats that differ from their assigned biome . Biogeographic provinces may originate due to various barriers, including physical (plate tectonics, topographic highs), climatic (latitudinal variation, seasonal range) and ocean chemical related (salinity, oxygen levels). The history of

420-463: Is the keystone species of the ecosystem of the Southern Ocean , and is an important food organism for whales , seals , leopard seals , fur seals , crabeater seals , squid , icefish , penguins , albatrosses and many other birds . The ocean there is so full of phytoplankton because water rises from the depths to the light-flooded surface, bringing nutrients from all oceans back to

462-755: The Antarctic Circumpolar Current to form, which isolated Antarctica climatically and caused it to become much colder. The Antarctic flora subsequently died out in Antarctica, but is still an important component of the flora of southern Neotropical ( Latin America and the Caribbean ) and Australasian realms , which were also former parts of Gondwana. Some botanists recognize an Antarctic Floristic Kingdom that includes Antarctica, New Zealand , and parts of Temperate South America where

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504-608: The Himalayas and the Sahara . The boundaries of ecoregions are often not as decisive or well recognized, and are subject to greater disagreement. Ecoregions are classified by biome type, which are the major global plant communities determined by rainfall and climate. Forests, grasslands (including savanna and shrubland), and deserts (including xeric shrublands ) are distinguished by climate ( tropical and subtropical vs. temperate and boreal climates) and, for forests, by whether

546-563: The Holarctic realm . Following the nomenclatural conventions set out in the International Code of Area Nomenclature , Morrone defined the next biogeographic kingdoms (or realms) and regions: The applicability of Udvardy scheme to most freshwater taxa is unresolved. 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

588-423: The floristic kingdoms of botany or zoogeographic regions of zoology . From 1872, Alfred Russel Wallace developed a system of zoogeographic regions, extending the ornithologist Philip Sclater 's system of six regions. 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

630-600: The photic zone . On August 20, 2014, scientists confirmed the existence of microorganisms living 800 metres (2,600 feet) below the ice of Antarctica . Millions of years ago, Antarctica was warmer and wetter, and supported the Antarctic flora , including forests of podocarps and southern beech . Antarctica was also part of the ancient supercontinent of Gondwanaland , which gradually broke up by continental drift starting 110 million years ago. The separation of South America from Antarctica 30–35 million years ago allowed

672-450: The "ecoregion" as a unit of analysis. The " Global 200 " is the list of ecoregions identified by WWF as priorities for conservation . Terrestrial ecoregions are land ecoregions, as distinct from freshwater and marine ecoregions. In this context, terrestrial is used to mean "of land" (soil and rock), rather than the more general sense "of Earth " (which includes land and oceans). WWF (World Wildlife Fund) ecologists currently divide

714-404: The 1960s, it was used originally in the field of biostratigraphy to denote intervals of geological strata with fossil content demonstrating a specific ecology. In Canadian literature, the term was used by Wiken in macro level land classification , with geographic criteria (see Ecozones of Canada ). Later, Schultz would use it with ecological and physiognomical criteria, in a way similar to

756-471: The Antarctic Flora is still a major component. The Antarctic realm is divided into 17 tundra ecoregions : Biogeographic realm A biogeographic realm is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions , which are further subdivided into ecoregions . A biogeographic realm

798-1095: The Antarctic realm, including Bouvet Island , the Crozet Islands , Heard Island , the Kerguelen Islands , the McDonald Islands , the Prince Edward Islands , the South Georgia Group , the South Orkney Islands , the South Sandwich Islands , and the South Shetland Islands . These islands have a somewhat milder climate than Antarctica proper, and support a greater diversity of tundra plants, although they are all too windy and cold to support trees. Antarctic krill

840-708: The Earth's surface based on life form , or the adaptation of animals, fungi, micro-organisms and plants to climatic, soil , and other conditions. Biomes are characterized by similar climax vegetation . Each realm may include a number of different biomes. A tropical moist broadleaf forest 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 distribution of organisms among

882-558: The Earth. The use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes . It is widely recognized that interlinked ecosystems combine to form a whole that is "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, and various interest groups from agricultural researchers to conservationists are using

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924-552: The Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as: A large area of land or water that contains a geographically distinct assemblage of natural communities that: According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has identified 867 terrestrial ecoregions, and approximately 450 freshwater ecoregions across

966-571: The WWF concept prioritizes biogeography, that is, the distribution of distinct species assemblages. In 2017, an updated terrestrial ecoregions dataset was released in the paper "An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm" led by E. Dinerstein with 48 co-authors. Using recent advances in satellite imagery the ecoregion perimeters were refined and the total number reduced to 846 (and later 844), which can be explored on

1008-793: The WWF system, the Australasia realm includes Australia , Tasmania , the islands of Wallacea , New Guinea , the East Melanesian Islands , New Caledonia , and New Zealand . Udvardy's Australian realm includes only Australia and Tasmania; he places Wallacea in the Indomalayan Realm, New Guinea, New Caledonia, and East Melanesia in the Oceanian Realm, and New Zealand in the Antarctic Realm. The Palearctic and Nearctic are sometimes grouped into

1050-523: The World (TEOW), led by D. Olsen, E. Dinerstein, E. Wikramanayake, and N. Burgess. While the two approaches are related, the Bailey ecoregions (nested in four levels) give more importance to ecological criteria and climate zones, while the WWF ecoregions give more importance to biogeography, that is, the distribution of distinct species assemblages. The TEOW framework originally delineated 867 terrestrial ecoregions nested into 14 major biomes, contained with

1092-783: The World, released in 2008, has 426 ecoregions covering virtually the entire non-marine surface of the earth. World Wildlife Fund (WWF) identifies twelve major habitat types of freshwater ecoregions: Large lakes, large river deltas, polar freshwaters, montane freshwaters, temperate coastal rivers, temperate floodplain rivers and wetlands, temperate upland rivers, tropical and subtropical coastal rivers, tropical and subtropical floodplain rivers and wetlands, tropical and subtropical upland rivers, xeric freshwaters and endorheic basins, and oceanic islands. The freshwater major habitat types reflect groupings of ecoregions with similar biological, chemical, and physical characteristics and are roughly equivalent to biomes for terrestrial systems. The Global 200 ,

1134-537: The areas of exposed rock and soil around the shore of the continent. Antarctica's two flowering plant species, the Antarctic hair grass ( Deschampsia antarctica ) and Antarctic pearlwort ( Colobanthus quitensis ), are found on the northern and western parts of the Antarctic Peninsula . Antarctica is also home to a diversity of animal life, including penguins , seals , and whales . Several Antarctic and sub-Antarctic island groups are considered part of

1176-480: The authors was to support global biodiversity conservation by providing a "fourfold increase in resolution over that of the 198 biotic provinces of Dasmann (1974) and the 193 units of Udvardy (1975)." In 2007, a comparable set of Marine Ecoregions of the World (MEOW) was published, led by M. Spalding, and in 2008 a set of Freshwater Ecoregions of the World (FEOW) was published, led by R. Abell. Bailey's ecoregion concept prioritizes ecological criteria and climate, while

1218-677: The broad latitudinal divisions of polar, temperate, and tropical seas, with subdivisions based on ocean basins (except for the southern hemisphere temperate oceans, which are based on continents). Major marine biogeographic realms, analogous to the eight terrestrial biogeographic realms , represent large regions of the ocean basins: Arctic , Temperate Northern Atlantic , Temperate Northern Pacific , Tropical Atlantic , Western Indo-Pacific , Central Indo-Pacific , Eastern Indo-Pacific , Tropical Eastern Pacific , Temperate South America , Temperate Southern Africa , Temperate Australasia , and Southern Ocean . A similar system of identifying areas of

1260-586: The concept of biome . In the Global 200 /WWF scheme, originally the term "biogeographic realm" in Udvardy sense was used. However, in a scheme of BBC , it was replaced by the term "ecozone". The World Wildlife Fund scheme is broadly similar to Miklos Udvardy 's system, the chief difference being the delineation of the Australasian realm relative to the Antarctic, Oceanic, and Indomalayan realms. In

1302-401: The delineation of ecoregions an imperfect science. Another complication is that environmental conditions across an ecoregion boundary may change very gradually, e.g. the prairie-forest transition in the midwestern United States, making it difficult to identify an exact dividing boundary. Such transition zones are called ecotones . Ecoregions can be categorized using an algorithmic approach or

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1344-405: The early 1970s, the term 'ecoregion' was introduced (short for ecological region), and R.G. Bailey published the first comprehensive map of U.S. ecoregions in 1976. The term was used widely in scholarly literature in the 1980s and 1990s, and in 2001 scientists at the U.S. conservation organization World Wildlife Fund (WWF) codified and published the first global-scale map of Terrestrial Ecoregions of

1386-501: The land surface of the Earth into eight biogeographical realms containing 867 smaller terrestrial ecoregions (see list ). The WWF effort is a synthesis of many previous efforts to define and classify ecoregions. The eight realms follow the major floral and faunal boundaries, identified by botanists and zoologists, that separate the world's major plant and animal communities. Realm boundaries generally follow continental boundaries, or major barriers to plant and animal distribution, like

1428-686: The ocean. According to Briggs and Morrone: According to the WWF scheme: Ecoregion An ecoregion ( ecological region ) is an ecologically and geographically defined area that is smaller than a bioregion , which in turn is smaller than a biogeographic realm . Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species . The biodiversity of flora , fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where

1470-472: The oceans for conservation purposes is the system of large marine ecosystems (LMEs), developed by the US National Oceanic and Atmospheric Administration (NOAA). A freshwater ecoregion is a large area encompassing one or more freshwater systems that contains a distinct assemblage of natural freshwater communities and species. The freshwater species, dynamics, and environmental conditions within

1512-430: The probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point). Ecoregions are also known as "ecozones" ("ecological zones"), although that term may also refer to biogeographic realms . Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework

1554-415: The quality, health, and integrity of ecosystems ". "Characteristics of geographical phenomena" may include geology , physiography , vegetation, climate, hydrology , terrestrial and aquatic fauna , and soils, and may or may not include the impacts of human activity (e.g. land use patterns, vegetation changes). There is significant, but not absolute, spatial correlation among these characteristics, making

1596-408: The term is somewhat vague. It has been used in many contexts: forest classifications (Loucks, 1962), biome classifications (Bailey, 1976, 2014), biogeographic classifications ( WWF / Global 200 scheme of Olson & Dinerstein, 1998), etc. The phrase "ecological region" was widely used throughout the 20th century by biologists and zoologists to define specific geographic areas in research. In

1638-454: The terrestrial ecoregions; only the priority conservation areas are listed. See Global 200 Marine ecoregions for a full list of marine ecoregions. In 2007, TNC and WWF refined and expanded this scheme to provide a system of comprehensive near shore (to 200 meters depth) Marine Ecoregions of the World (MEOW). The 232 individual marine ecoregions are grouped into 62 marine provinces , which in turn group into 12 marine realms , which represent

1680-913: The trees are predominantly conifers ( gymnosperms ), or whether they are predominantly broadleaf ( Angiosperms ) and mixed (broadleaf and conifer). Biome types like Mediterranean forests, woodlands, and scrub ; tundra ; and mangroves host very distinct ecological communities, and are recognized as distinct biome types as well. Marine ecoregions are: "Areas of relatively homogeneous species composition , clearly distinct from adjacent systems….In ecological terms, these are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species." They have been defined by The Nature Conservancy (TNC) and World Wildlife Fund (WWF) to aid in conservation activities for marine ecosystems . Forty-three priority marine ecoregions were delineated as part of WWF's Global 200 efforts. The scheme used to designate and classify marine ecoregions

1722-436: The world's 8 major biogeographical realms. Subsequent regional papers by the co-authors covering Africa, Indo-Pacific, and Latin America differentiate between ecoregions and bioregions, referring to the latter as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)". The specific goal of

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1764-406: The world's biogeographic realms has been influenced by the distribution of landmasses , as shaped by plate tectonics over the geological history of the Earth . The "biogeographic realms" of Udvardy were defined based on taxonomic composition. The rank corresponds more or less to the floristic kingdoms and zoogeographic regions . The usage of the term "ecozone" is more variable. Beginning in

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