A biome () is a biogeographical unit consisting of a biological

community A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, t ...

that has formed in response to the physical environment in which they are found and a shared regional

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

. Biomes may span more than one continent. Biome is a broader term than

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

and can comprise a variety of habitats. While a biome can cover large areas, a microbiome is a mix of organisms that coexist in a defined space on a much smaller scale. For example, the

human microbiome The human microbiome is the aggregate of all microbiota that reside on or within human tissues and biofluids along with the corresponding anatomical sites in which they reside, including the skin, mammary glands, seminal fluid, uterus, ovarian ...

is the collection of bacteria, viruses, and other microorganisms that are present on or in a human body. A biota is the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biotas of the Earth make up the

biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also ...

Etymology

The term was suggested in 1916 by Clements, originally as a synonym for ''

biotic community A biocenosis (UK English, ''biocoenosis'', also biocenose, biocoenose, biotic community, biological community, ecological community, life assemblage), coined by Karl Möbius in 1877, describes the interacting organisms living together in a ha ...

'' of Möbius (1877). Later, it gained its current definition, based on earlier concepts of phytophysiognomy,

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

and

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic charac ...

(used in opposition to

flora Flora is all the plant life present in a particular region or time, generally the naturally occurring ( indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. ...

), with the inclusion of the animal element and the exclusion of the taxonomic element of species composition. In 1935,

Tansley Tansley is a village on the southern edge of the Derbyshire Peak District, two miles east of Matlock. History Tansley is recorded in the Domesday Book as Taneslege, and its name comes from the combination of the Old English elements ''tān'' a ...

added the climatic and soil aspects to the idea, calling it ''

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

''. The

International Biological Program The International Biological Program (IBP) was an effort between 1964 and 1974 to coordinate large-scale ecological and environmental studies. Organized in the wake of the successful International Geophysical Year (IGY) of 1957-1958, the Internati ...

(1964–74) projects popularized the concept of biome. However, in some contexts, the term biome is used in a different manner. In German literature, particularly in the Walter terminology, the term is used similarly as ''

biotope A biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. ''Biotope'' is almost synonymous with the term "habitat", which is more commonly used in English-speaking countr ...

'' (a concrete geographical unit), while the biome definition used in this article is used as an international, non-regional, terminology—irrespectively of the continent in which an area is present, it takes the same biome name—and corresponds to his "zonobiome", "orobiome" and "pedobiome" (biomes determined by climate zone, altitude or soil). In Brazilian literature, the term "biome" is sometimes used as synonym of ''

biogeographic province This page features a list of biogeographic provinces that were developed by Miklos Udvardy in 1975,Udvardy, M. D. F. (1975). ''A classification of the biogeographical provinces of the world''. IUCN Occasional Paper no. 18. Morges, Switzerland: IUCN ...

'', an area based on species composition (the term ''

floristic province A phytochorion, in phytogeography, is a geographic area with a relatively uniform composition of plant species. Adjacent phytochoria do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both r ...

'' being used when plant species are considered), or also as synonym of the "morphoclimatic and phytogeographical domain" of Ab'Sáber, a geographic space with subcontinental dimensions, with the predominance of similar geomorphologic and climatic characteristics, and of a certain vegetation form. Both include many biomes in fact.

Classifications

To divide the world into a few ecological zones is difficult, notably because of the small-scale variations that exist everywhere on earth and because of the gradual changeover from one biome to the other. Their boundaries must therefore be drawn arbitrarily and their characterization made according to the average conditions that predominate in them. A 1978 study on North American grasslands found a positive logistic correlation between

evapotranspiration Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transp ...

in mm/yr and above-ground net primary production in g/m²/yr. The general results from the study were that precipitation and water use led to above-ground primary production, while

solar irradiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

and temperature lead to below-ground primary production (roots), and temperature and water lead to cool and warm season growth habit. These findings help explain the categories used in Holdridge's bioclassification scheme (see below), which were then later simplified by Whittaker. The number of classification schemes and the variety of determinants used in those schemes, however, should be taken as strong indicators that biomes do not fit perfectly into the classification schemes created.

Holdridge (1947, 1964) life zones

In 1947, the American botanist and climatologist

Leslie Holdridge Leslie Ransselaer Holdridge (September 29, 1907 – June 19, 1999) was an American botanist and climatologist. He was the father of composer Lee Holdridge as well as the father of Leslie A. Holdridge, Lorena Holdridge, Marbella Holdridge, Marly ...

classified climates based on the biological effects of temperature and

rainfall Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

under the assumption that these two

abiotic In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them under ...

factors are the largest determinants of the types of vegetation found in a habitat. Holdridge uses the four axes to define 30 so-called "humidity provinces", which are clearly visible in his diagram. While this scheme largely ignores soil and sun exposure, Holdridge acknowledged that these were important.

Allee (1949) biome-types

The principal biome-types by Allee (1949): *

Tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless mou ...

Taiga Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, sp ...

Deciduous forest In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals ...

Grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

s *

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 denudation. About on ...

* High plateaus *

Tropical forest Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds. Some tropical fore ...

Minor terrestrial biomes Minor may refer to: * Minor (law), a person under the age of certain legal activities. ** A person who has not reached the age of majority * Academic minor, a secondary field of study in undergraduate education Music theory *Minor chord ** Bar ...

Kendeigh (1961) biomes

The principal biomes of the world by Kendeigh (1961): * ''Terrestrial'' ** Temperate deciduous forest **

Coniferous forest Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All exta ...

Woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

Chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranea ...

Tropical savanna Tropical and subtropical grasslands, savannas, and shrublands is a terrestrial biome defined by the World Wide Fund for Nature. The biome is dominated by grass and/or shrubs located in semi-arid to semi-humid climate regions of subtropical and t ...

* Marine ** Oceanic

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

and

nekton Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...

** Balanoid-gastropod-

thallophyte Thallophytes (Thallophyta, Thallophyto or Thallobionta) are a polyphyletic group of non-motile organisms traditionally described as "thalloid plants", "relatively simple plants" or "lower plants". They form a division of kingdom Plantae that inc ...

Pelecypod Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biva ...

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

Coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...

Whittaker (1962, 1970, 1975) biome-types

Whittaker classified biomes using two abiotic factors: precipitation and temperature. His scheme can be seen as a simplification of Holdridge's; more readily accessible, but missing Holdridge's greater specificity. Whittaker based his approach on theoretical assertions and empirical sampling. He had previously compiled a review of biome classifications.

Key definitions for understanding Whittaker's scheme

Physiognomy Physiognomy (from the Greek , , meaning "nature", and , meaning "judge" or "interpreter") is the practice of assessing a person's character or personality from their outer appearance—especially the face. The term can also refer to the genera ...

: sometimes referring to the plants' appearance; or the biome's apparent characteristics, outward features, or appearance of ecological communities or species - including plants. * Biome: a grouping of terrestrial ecosystems on a given continent that is similar in vegetation structure, physiognomy, features of the environment and characteristics of their animal communities. *

Formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

: a major kind of community of plants on a given continent. * Biome-type: grouping of convergent biomes or formations of different continents, defined by physiognomy. * Formation-type: a grouping of convergent formations. Whittaker's distinction between biome and formation can be simplified: formation is used when applied to

plant communities A plant community is a collection or association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The components of each plant ...

only, while biome is used when concerned with both plants and animals. Whittaker's convention of biome-type or formation-type is a broader method to categorize similar communities.

Whittaker's parameters for classifying biome-types

Whittaker used what he called "gradient analysis" of ecocline patterns to relate communities to climate on a worldwide scale. Whittaker considered four main ecoclines in the terrestrial realm. # Intertidal levels: The wetness gradient of areas that are exposed to alternating water and dryness with intensities that vary by location from high to low tide # Climatic moisture gradient # Temperature gradient by altitude # Temperature gradient by latitude Along these gradients, Whittaker noted several trends that allowed him to qualitatively establish biome-types: * The gradient runs from favorable to the extreme, with corresponding changes in productivity. * Changes in physiognomic complexity vary with how favorable of an environment exists (decreasing community structure and reduction of stratal differentiation as the environment becomes less favorable). * Trends in the diversity of structure follow trends in species diversity; alpha and beta species diversities decrease from favorable to extreme environments. * Each growth-form (i.e. grasses, shrubs, etc.) has its characteristic place of maximum importance along the ecoclines. * The same growth forms may be dominant in similar environments in widely different parts of the world. Whittaker summed the effects of gradients (3) and (4) to get an overall temperature gradient and combined this with a gradient (2), the moisture gradient, to express the above conclusions in what is known as the Whittaker classification scheme. The scheme graphs average annual precipitation (x-axis) versus average annual temperature (y-axis) to classify biome-types.

Biome-types

Tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equator ...

Tropical seasonal rainforest The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

semideciduous Semi-deciduous or semi-evergreen is a botanical term which refers to plants that lose their foliage for a very short period, when old leaves fall off and new foliage growth is starting. This phenomenon occurs in tropical and sub-tropical woody spec ...

Temperate giant rainforest In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges through ...

Montane rainforest Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

# Temperate deciduous forest #

Temperate evergreen forest In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges through ...

#* needleleaf #*

sclerophyll Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaves, short internodes (the distance between leaves along the stem) and leaf orientation which is parallel or oblique to direct ...

# Subarctic-subalpine needle-leaved forests (

taiga Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, sp ...

) #

Elfin woodland Dwarf forest, elfin forest, or pygmy forest is an uncommon ecosystem featuring miniature trees, inhabited by small species of fauna such as rodents and lizards. They are usually located at high elevations, under conditions of sufficient air humi ...

Thorn forests and woodlands Thorn(s) or The Thorn(s) may refer to: Botany * Thorns, spines, and prickles, sharp structures on plants * ''Crataegus monogyna'', or common hawthorn, a plant species Comics and literature * Rose and Thorn, the two personalities of two DC Comic ...

Thorn scrub Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this h ...

Temperate woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (se ...

Temperate shrublands Temperate grasslands, savannas, and shrublands is a terrestrial biome defined by the World Wide Fund for Nature. The predominant vegetation in this biome consists of grass and/or shrubs. The climate is temperate and ranges from semi-arid to s ...

heath A heath () is a shrubland habitat found mainly on free-draining infertile, acidic soils and characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great Britain—a cooler a ...

#* subalpine-needleleaf #* subalpine-broadleaf #

Savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground ...

# Temperate grassland #

Alpine grasslands Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National ...

# Tropical desert # Warm-temperate desert #

Cool temperate desert scrub Cool commonly refers to: * Cool, a moderately low temperature * Cool (aesthetic), an aesthetic of attitude, behavior, and style Cool or COOL may also refer to: Economics * Country of origin labelling * mCOOL - US consumer legislation to enf ...

# Arctic-alpine desert #

Bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...

Tropical fresh-water swamp forest The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

Temperate fresh-water swamp forest In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

Mangrove swamp Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand fre ...

# Salt marsh # Wetland

Goodall (1974–) ecosystem types

The multi-authored series ''Ecosystems of the World'', edited by

David W. Goodall David William Goodall (4 April 1914 – 10 May 2018) was an English-born Australian botanist and ecologist. He was influential in the early development of statistical methods in plant communities. He worked as researcher and professor in Englan ...

, provides a comprehensive coverage of the major "ecosystem types or biomes" on Earth:

Walter (1976, 2002) zonobiomes

The eponymously-named

Heinrich Walter Heinrich Karl Walter (21 October 1898 – 15 October 1989) was a German-Russian botanist and eco-physiologist. Life Walter, the son of a doctor, was born in Odessa. He studied plant biology at the University of Odessa from 1915 to 1917. In 1918 ...

classification scheme considers the seasonality of temperature and precipitation. The system, also assessing precipitation and temperature, finds nine major biome types, with the important climate traits and

vegetation type Vegetation classification is the process of classifying and mapping the vegetation over an area of the earth's surface. Vegetation classification is often performed by state based agencies as part of land use, resource and environmental managemen ...

s. The boundaries of each biome correlate to the conditions of moisture and cold stress that are strong determinants of plant form, and therefore the vegetation that defines the region. Extreme conditions, such as flooding in a swamp, can create different kinds of communities within the same biome.

Schultz (1988) eco-zones

Schultz (1988, 2005) defined nine ''ecozones'' (his concept of ecozone is more similar to the concept of biome than to the concept of

ecozone An Ecozone may refer to: * Ecozone (Canada), one of 15 first-level ecological land classifications in Canada * Biogeographic realm, the broadest biogeographic division of Earth's land surface (referred to as ''ecozone'' by BBC) * Biome, a large ...

of BBC):Schultz, J. ''Die Ökozonen der Erde'', 1st ed., Ulmer, Stuttgart, Germany, 1988, 488 pp.; 2nd ed., 1995, 535 pp.; 3rd ed., 2002; 4th ed., 2008; 5th ed., 2016. Transl.: ''The Ecozones of the World: The Ecological Divisions of the Geosphere''. Berlin: Springer-Verlag, 1995; 2nd ed., 2005

# polar/subpolar zone # boreal zone # humid mid-latitudes # dry mid-latitudes # subtropics with winter rain # subtropics with year-round rain # dry tropics and subtropics # tropics with summer rain # tropics with year-round rain

Bailey (1989) ecoregions

Robert Bailey (geographer), Robert G. Bailey nearly developed a

biogeographical Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

classification system of

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) 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 ...

s for the United States in a map published in 1976. He subsequently expanded the system to include the rest of North America in 1981, and the world in 1989. The Bailey system, based on climate, is divided into four domains (polar, humid temperate, dry, and humid tropical), with further divisions based on other climate characteristics (subarctic, warm temperate, hot temperate, and subtropical; marine and continental; lowland and mountain). * 100 Polar Domain ** 120

Division (Köppen: Ft) ** M120 Tundra Division – Mountain Provinces ** 130 Subarctic Division (Köppen: E) ** M130 Subarctic Division – Mountain Provinces * 200 Humid Temperate Domain ** 210 Warm Continental Division (Köppen: portion of Dcb) ** M210 Warm Continental Division – Mountain Provinces ** 220 Hot Continental Division (Köppen: portion of Dca) ** M220 Hot Continental Division – Mountain Provinces ** 230 Subtropical Division (Köppen: portion of Cf) ** M230 Subtropical Division – Mountain Provinces ** 240 Marine Division (Köppen: Do) ** M240 Marine Division – Mountain Provinces ** 250 Prairie Division (Köppen: arid portions of Cf, Dca, Dcb) ** 260 Mediterranean Division (Köppen: Cs) ** M260 Mediterranean Division – Mountain Provinces * 300 Dry Domain ** 310 Tropical/Subtropical Steppe Division ** M310 Tropical/Subtropical Steppe Division – Mountain Provinces ** 320 Tropical/Subtropical Desert Division ** 330 Temperate Steppe Division ** 340 Temperate Desert Division * 400 Humid Tropical Domain ** 410 Savanna Division ** 420 Rainforest Division

Olson & Dinerstein (1998) biomes for WWF / Global 200

A team of biologists convened by the

World Wildlife Fund The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the W ...

(WWF) developed a scheme that divided the world's land area into

biogeographic realm A biogeographic realm or ecozone 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. ...

s (called "ecozones" in a BBC scheme), and these into

ecoregions An ecoregion (ecological region) or ecozone (ecological zone) 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 l ...

(Olson & Dinerstein, 1998, etc.). Each ecoregion is characterized by a main biome (also called major habitat type).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

. This classification is used to define the

Global 200 The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature ( WWF), the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or w ...

list of

s identified by the WWF as priorities for conservation. For the

terrestrial ecoregions An ecoregion (ecological region) or ecozone (ecological zone) 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 l ...

, there is a specific EcoID, format XXnnNN (XX is the

, nn is the biome number, NN is the individual number).

Biogeographic realms (terrestrial and freshwater)

* NA:

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America ...

* PA:

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sib ...

* AT:

Afrotropic The Afrotropical realm is one of Earth's eight biogeographic realms. It includes Africa south of the Sahara Desert, the majority of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the island ...

* IM:

Indomalaya The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia. Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indi ...

* AA:

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...

* NT:

Neotropic The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In ...

* OC:

Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...

* AN:

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and othe ...

The applicability of the realms scheme above - based on Udvardy (1975)—to most freshwater taxa is unresolved.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

.

Biogeographic realms ( Marine ecoregion, marine)

Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

Temperate Northern Atlantic The Temperate Northern Atlantic is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of the North Atlantic Ocean and connecting seas, including the Mediterranean Sea, Black Sea, and northern Gulf of Mexic ...

Temperate Northern Pacific The Temperate Northern Pacific is a biogeographic region of the Earth's seas, comprising the temperate waters of the northern Pacific Ocean. The Temperate Northern Pacific connects, via the Bering Sea, to the Arctic marine realm, which includes ...

* Tropical Atlantic *

Western Indo-Pacific The Western Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the eastern and central Indian Ocean. It is part of the larger Indo-Pacific, which includes the tropical Indian Ocean, the western and centra ...

Central Indo-Pacific The Central Indo-Pacific is a biogeographic region of Earth's seas, comprising the tropical waters of the western Pacific Ocean, the eastern Indian Ocean, and the connecting seas. The Central Indo-Pacific is a part of the larger Indo-Pacific, w ...

* Eastern Indo-Pacific * Tropical Eastern Pacific * Temperate South America * Temperate Southern Africa * Temperate Australasia *

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...

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

.

Biomes (terrestrial)

Tropical and subtropical moist broadleaf forests Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature. Description TSMF is generally found in large, discon ...

(tropical and subtropical, humid) #

Tropical and subtropical dry broadleaf forests The tropical and subtropical dry broadleaf forest is a habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive ...

(tropical and subtropical, semihumid) #

Tropical and subtropical coniferous forests Tropical and subtropical coniferous forests are a tropical forest habitat type defined by the World Wide Fund for Nature. These forests are found predominantly in North and Central America and experience low levels of precipitation and moderate va ...

(tropical and subtropical, semihumid) #

Temperate broadleaf and mixed forests Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These f ...

(temperate, humid) #

Temperate coniferous forests Temperate coniferous forest is a terrestrial biome defined by the World Wide Fund for Nature. Temperate coniferous forests are found predominantly in areas with warm summers and cool winters, and vary in their kinds of plant life. In some, needl ...

(temperate, humid to semihumid) #

Boreal forests/taiga Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, ...

(subarctic, humid) #

Tropical and subtropical grasslands, savannas, and shrublands Tropical and subtropical grasslands, savannas, and shrublands is a terrestrial biome defined by the World Wide Fund for Nature. The biome is dominated by grass and/or shrubs located in semi-arid to semi-humid climate regions of subtropical and t ...

(tropical and subtropical, semiarid) #

Temperate grasslands, savannas, and shrublands Temperate grasslands, savannas, and shrublands is a terrestrial biome defined by the World Wide Fund for Nature. The predominant vegetation in this biome consists of grass and/or shrubs. The climate is temperate and ranges from semi-arid to sem ...

(temperate, semiarid) #

Flooded grasslands and savannas Flooded grasslands and savannas is a terrestrial biome of the WWF biogeographical system, consisting of large expanses or complexes of flooded grasslands. These areas support numerous plants and animals adapted to the unique hydrologic regimes ...

(temperate to tropical, fresh or brackish water inundated) #

Montane grasslands and shrublands Montane grasslands and shrublands is a biome defined by the World Wildlife Fund. The biome includes high elevation grasslands and shrublands around the world. The term "montane" in the name of the biome refers to "high elevation", rather than th ...

(alpine or montane climate) #

(Arctic) #

Mediterranean forests, woodlands, and scrub Mediterranean forests, woodlands, and scrub is a biome defined by the World Wide Fund for Nature. The biome is generally characterized by dry summers and rainy winters, although in some areas rainfall may be uniform. Summers are typically hot in ...

sclerophyll forest Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaves, short internodes (the distance between leaves along the stem) and leaf orientation which is parallel or oblique to direct ...

s (temperate warm, semihumid to semiarid with winter rainfall) #

Deserts and xeric shrublands Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this h ...

(temperate to tropical, arid) #

Mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

(subtropical and tropical, salt water inundated)

Biomes (freshwater)

According to the WWF, the following are classified as

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

biomes: * Large

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s * Large

river deltas A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rare ...

* Polar

s * Montane

s * Temperate coastal rivers * Temperate floodplain rivers and

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...

s * Temperate upland rivers * Tropical and subtropical coastal rivers * Tropical and subtropical floodplain rivers and

s * Tropical and subtropical upland rivers * Xeric freshwaters and

endorheic basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...

s * Oceanic islands

Biomes (marine)

Biomes of the coastal and

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

areas (

neritic zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

): * Polar * Temperate shelves and sea * Temperate

upwelling Upwelling is an physical oceanography, oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted ...

* Tropical

* Tropical coral

Summary of the scheme

Biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also ...

Biogeographic realm A biogeographic realm or ecozone 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. ...

s (terrestrial) (8) ***

Ecoregions An ecoregion (ecological region) or ecozone (ecological zone) 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 l ...

(867), each characterized by a main biome type (14) ****

Ecosystems An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

(

s) *

s (freshwater) (8) ***

(426), each characterized by a main biome type (12) ****

(biotopes) *

** Biogeographic realms (marine) (12) *** (

Marine provinces The following is a list of marine ecoregions, as defined by the WWF and The Nature Conservancy The WWF/Nature Conservancy scheme groups the individual ecoregions into 12 marine realms, which represent the broad latitudinal divisions of polar, te ...

) (62) ****

(232), each characterized by a main biome type (5) *****

(biotopes) Example: *

***

Ecoregion An ecoregion (ecological region) or ecozone (ecological zone) 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 ...

Dinaric Mountains mixed forests The Dinaric Mountains mixed forests are a terrestrial ecoregion of the temperate broadleaf and mixed forests biome in Southeastern Europe, according to both the WWF and Digital Map of European Ecological Regions by the European Environment Agenc ...

(PA0418); biome type:

temperate broadleaf and mixed forests Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These f ...

****

Ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

Orjen Orjen (Serbian Cyrillic: Орјен, ) is a transboundary Dinaric Mediterranean limestone mountain range, located between southernmost Bosnia and Herzegovina and southwestern Montenegro. Its highest peak is Veliki kabao, which stands at . ...

, vegetation belt between 1,100 and 1,450 m, Oromediterranean zone, nemoral zone (temperate zone) *****

Biotope A biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. ''Biotope'' is almost synonymous with the term "habitat", which is more commonly used in English-speaking countr ...

: ''Oreoherzogio-Abietetum illyricae'' Fuk. ( Plant list) ****** Plant: Silver fir (''

Abies alba ''Abies alba'', the European silver fir or silver fir, is a fir native to the mountains of Europe, from the Pyrenees north to Normandy, east to the Alps and the Carpathians, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, and sou ...

'')

Other biomes

Marine biomes

Pruvot (1896) zones or "systems": *

Littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal ...

Pelagic zone The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

Abyssal zone The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. "Abyss" derives from the Greek word , meaning bottomless. At depths of , this zone remains in perpetual darkness. It covers 83% of the total area of the ocean an ...

Longhurst (1998) biomes: * Coastal * Polar * Trade wind * Westerly Other marine

habitat type In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physica ...

s (not covered yet by the Global 200/WWF scheme): *

Open sea The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

Deep sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...

Hydrothermal vent A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspo ...

s *

Cold seep A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature of the see ...

s *

Benthic zone The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...

(trades and westerlies) * Abyssal * Hadal (ocean trench) * Littoral/

Intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

Salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

Estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

* Coastal lagoons/Atoll lagoons *

Kelp forest Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Ea ...

Pack ice Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.).Leppäranta, M. 2011. The Drift of Sea Ice. Berlin: Springer-Verlag. Unlike fast ice, which is "faste ...

Anthropogenic biomes

Humans have altered global patterns of

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...

and

processes. As a result, vegetation forms predicted by conventional biome systems can no longer be observed across much of Earth's land surface as they have been replaced by crop and rangelands or cities. Anthropogenic biomes provide an alternative view of the terrestrial biosphere based on global patterns of sustained direct human interaction with ecosystems, including

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...

human settlement In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can range from a minuscule number of dwellings grouped together to the largest of citi ...

urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly th ...

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. ...

and other uses of land. Anthropogenic biomes offer a way to recognize the irreversible coupling of human and ecological systems at global scales and manage Earth's biosphere and anthropogenic biomes. Major anthropogenic biomes: * Dense settlements *

Cropland Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous with bot ...

s *

Rangeland Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, sava ...

s * Forested * Indoor

Microbial biomes

Endolithic biomes

The

endolith An endolith or endolithic is an organism ( archaeon, bacterium, fungus, lichen, algae or amoeba) that is able to acquire the necessary resources for growth in the inner part of a rock, mineral, coral, animal shells, or in the pores between min ...

ic biome, consisting entirely of microscopic life in rock pores and cracks, kilometers beneath the surface, has only recently been discovered, and does not fit well into most classification schemes.

Effects of climate change

Anthropogenic

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

has the potential to greatly alter the distribution of Earth's biomes. Meaning, biomes around the world could change so much that they would be at risk of becoming new biomes entirely. General frequency models have been a staple in finding out the impact climate change could have on biomes. More specifically, 54% and 22% of global land area will experience climates that correspond to other biomes. 3.6% of land area will experience climates that are completely new or unusual. Average temperatures have risen more than twice the usual amount in both arctic and mountainous biomes, which leads to the conclusion that arctic and mountainous biomes are currently the most vulnerable to climate change. The current reasoning surrounding as to why this is the case are based around the fact that colder environments tend to reflect more sunlight, as a result of the snow and ice covering the ground. Since the annual average temperatures are rising, ice and snow is melting. As a result,

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refle ...

is lowered. Keeping a keen eye on terrestrial biomes is important, as they play a crucial role in climate regulation. South American terrestrial biomes have been predicted to go through the same temperature trends as arctic and mountainous biomes. With its annual average temperature continuing to increase, the moisture currently located in forest biomes will dry up.