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Bioregions 2023
Bioregions 2023
If Nature were to draw a map of the world, what would it look
like?
We've grown accustomed to seeing the world divided into countries,
states, and provinces, but there is another way to see and better
understand the planet we call home. One Earth presents a novel
biogeographical framework called Bioregions 2023, which delineates
185 discrete bioregions organized within the world's major
biogeographical realms. The bioregions, and the iconic species
associated with each, can be explored through One Earth's Interactive
Navigator.
Bioregions of the Earth
Bioregions 2023: a new map of the Earth created by intersecting
biomes with large-scale geological structures and ecoregional
groupings to delineate 185 discrete bioregions. Download Map (6 MB).
Credit: Karl Burkart, One Earth
With input from an array of field scientists, conservation experts,
and geographers, Bioregions 2023 provides a framework for collective
action to protect and conserve our planet -- from scientific research
and governance initiatives to philanthropic grantmaking and public
advocacy. It can also be useful as an educational tool, helping
people better understand the underlying ecological fabric of life
that surrounds them.
What is a bioregion?
A bioregion is a geographical area defined not by political
boundaries but by ecological systems. A bioregion is smaller in scale
than a biogeographical realm but larger than an ecoregion or an
ecosystem. On land, the most widely held bioregional framework is the
'biome' (sometimes called an 'ecozone') -- a broad community of
plants and animals adapted to specific climatic conditions found
across a range of continents. There are 14 widely held biome types:
* Deserts & Xeric Shrublands (rust)
* Mountain Grasslands & Shrublands (beige)
* Temperate Grasslands, Savannas & Shrublands (yellow)
* Tropical & Subtropical Grasslands, Savannas & Shrublands
(orange)
* Flooded Grasslands & Savannas (light blue)
* Mangroves (pink)
* Mediterranean Forests, Woodlands & Scrub (red)
* Temperate Broadleaf & Mixed Forests (dark green)
* Temperate Conifer Forests (grey-green)
* Tropical & Subtropical Coniferous Forests (light green)
* Tropical & Subtropical Dry Broadleaf Forests (olive green)
* Tropical & Subtropical Moist Broadleaf Forests (bright green)
* Boreal Forests/Taiga (medium blue)
* Tundra (teal)
Biome map - Bioregions 2023
The Earth's 14 major biomes, which include 6 subtypes of the generic
forest biome -- boreal, temperate broadleaf, temperate conifer,
tropical moist broadleaf, tropical dry broadleaf, and tropical
conifer. Biomes provide the highest order organizing principle used
in the development of Bioregions 2023. Download Map (6 MB). Credit:
Karl Burkart, One Earth
Biomes provide the highest-order organizing principle used in the
development of One Earth's Bioregions 2023 framework. Conceptually,
bioregions are major subdivisions of Earth's biomes, contained within
established realms and delineated by a process of intersecting biomes
with large-scale geological structures -- mountain ranges, plains,
plateaus, and basins - as well as commonly used climate zones. The
bioregions incorporate adjoining freshwater and marine areas with an
average land area of approximately 715,000 km^2.
What is a realm?
The 185 bioregions are organized within the world's major
biogeographical 'realms,' the broadest division of the Earth's land
surface within which groupings of organisms share a common
evolutionary history -- Nearctic, Neotropic, Palearctic, Afrotropic,
Indomalayan, Australasian, Oceanian, and Antarctic. The realms
roughly correspond to the major continents of the Earth but are
further subdivided to coincide with commonly held regional divisions.
For example, the Neotropic realm is divided into "Central America"
and "Southern America." These realm divisions - 14 in total - are
used as the overarching content framework for the One Earth website
and its Project Marketplace.
Realms map - Bioregions 2023
The 14 biogeographical realms of the Earth corresponding with
commonly held regional divisions. Between 3 and 24 bioregions are
contained within each realm in the Bioregions 2023 framework. Credit:
Karl Burkart, One Earth
Bioregions are fully nested within their parent realm, so each realm
contains a finite number of bioregions, which can be further
clustered into subrealms (defined below):
* Subarctic America (north Nearctic): 9 bioregions, 4 subrealms
* Northern America (greater Nearctic): 22 bioregions, 6 subrealms
* Central America & Caribbean (north Neotropic): 6 bioregions, 2
subrealms
* Southern America (greater Neotropic): 23 bioregions, 5 subrealms
* Subarctic Eurasia (north Palearctic): 8 bioregions, 4 subrealms
* Western Eurasia (west Palearctic, aka W. Europe): 13 bioregions,
5 subrealms
* Central Eurasia (central Palearctic, aka C. Asia): 11 bioregions,
5 subrealms
* Eastern Eurasia (east Palearctic, aka E. Asia): 16 bioregions, 6
subrealms
* Southern Eurasia (south Palearctic, aka MENA): 5 bioregions, 2
subrealms
* Afrotropics (aka Sub-Saharan Africa): 24 bioregions, 5 subrealms
* Indomalaya (aka South & Southeast Asia): 18 bioregions, 3
subrealms
* Australasia: 16 bioregions, 3 subrealms
* Oceania: 11 bioregions (not clustered)
* Antarctica: 3 bioregions (not clustered)
What is an ecoregion?
Ecoregions are the building blocks that make up each bioregion.
Ecoregions are used to describe areas where ecosystems are generally
similar, providing a spatial framework for the research, assessment,
and monitoring of ecosystem functionality. There are many definitions
of terrestrial ecoregions. The US Environmental Protection Agency
uses an ecoregional framework developed in the 1980s by James Overnik
with four nesting scales. Level I ecoregions are roughly comparable
to what we now call "biomes." Level II ecoregions are broad divisions
of Level I, roughly equivalent in scale to One Earth's bioregions.
Level III ecoregions are an intermediate scale of ecological areas
nested within Level II. And Level IV ecoregions are much more
detailed ecological units that most would refer to as 'ecosystems'
nested within Level III.
An international consortium of conservation scientists recently
released an updated map of the world's terrestrial ecoregions in the
paper "An Ecoregion-Based Approach to Protecting the Terrestrial
Realm" (Dinerstein et al. 2017). This effort used recent advances in
satellite imagery and remote sensing to identify 844 discreet
ecoregions of the world (roughly equivalent to Level III ecoregions).
These ecoregions provide the building blocks for Bioregions 2023.
They are widely cited in scientific literature on conservation
biology and frequently used for local-scale conservation planning
efforts. The ecoregions can be explored through an interactive web
application developed by RESOLVE and Google Earth Engine, with
detailed ecoregion profiles provided by One Earth.
Ecoregion map - Bioregions 2023
The 844 terrestrial ecoregions of the Earth (Dinerstein et al. 2017)
overlayed with Bioregions 2023 polygons. A finite number of
ecoregions are nested within each bioregion. Download Map (6 MB).
Credit: Karl Burkart, One Earth
While the terrestrial ecoregions are a powerful geospatial framework
for scientific efforts, they are often too small and too numerous to
be readily adopted for the purposes of broader public engagement and
resource allocation. In many cases, the spatial configuration of one
ecoregion is embedded tightly within another and thus should not be
considered apart, for example, when setting national conservation
targets under the Kunming-Montreal Global Biodiversity Framework. One
clear example of this is the Italian Peninsula, where Mediterranean
Woodlands and Scrub dominate, but which also contains the Apennines
forest ecoregion. In other cases, groups of similar ecoregions that
are adjacent to each other, for example, the three northern grassland
ecoregions just to the east of the Rockies, share similar attributes
and thus, from a conservation perspective, could be considered in
tandem. It is for this reason that One Earth undertook the
development of the Bioregions 2023 framework.
One major benefit of this bioregional framework is that it also
allows for the integration of all three types of ecoregions -
terrestrial, freshwater, and marine -- into one cohesive system. The
portion of rivers, streams, lakes, and ponds that flow through a
terrestrial ecoregion are included within the bioregion, and in some
cases, a watershed's footprint influences the grouping of overlapping
terrestrial ecoregions. Similarly, bioregions with coastal edges are
extended outward to a corresponding country's Exclusive Economic Zone
(EEZ) boundaries. While EEZs are administrative boundaries, not
biological ones, they effectively provide an ecosystem constraint, as
most fishing and industrial activities occur within EEZs. "Marine
Ecoregions of the World" (Spalding et al. 2007) is a key reference
for Bioregions 2023 and, in some cases, informs the clustering of
terrestrial ecoregions.
Marine map - Bioregions 2023
The 62 marine provinces from "Marine Ecoregions of the World"
(Spalding et al. 2007) overlayed with Bioregions 2023 polygons.
Download Map (6 MB). Credit: Karl Burkart, One Earth
The five rules for establishing a bioregion
To establish the boundaries of each bioregion, a set of five rules
was consistently applied across all realms, and specific scientific
publications pertaining to each realm were referenced in order to
align the bioregions as closely as possible with commonly held
ecological divisions by continent. The top-level rules used in the
development of the Bioregions 2023 framework are as follows:
1. Bioregions are contained within one of the 14 biogeographical
realms (as defined above). A bioregion cannot cross over from one
realm to another.
2. Bioregions are predominantly subdivisions of the major biomes,
defined by intersecting biomes with large-scale geological
structures -- mountain ranges, plains, plateaus, and basins - and
commonly used climate zones. An example of this is the great
plains of the Midwest US, divided into three bioregions -- north,
south, and central.
3. Bioregions often consist of one biome type, but in some cases,
ecoregions belonging to another biome are included when those
ecoregions are embedded or closely interlinked with an adjoining
ecoregion. An example of this is the Guianan savanna, which
cannot be separated from the adjacent Guianan forests.
4. Ecoregions are the building blocks of each bioregion. An
ecoregion is never split between two bioregions (with the
exception of mangroves, which often span across multiple
bioregions).
5. Bioregions include the marine areas beyond the coastline. These
are demarcated using the EEZ boundary lines, as these waters are
often heavily fished or experience impacts from activity on
adjacent land areas. In some cases, marine provinces (Spalding et
al. 2007) are used to articulate groupings of ecoregions within a
bioregion.
The application of these five rules resulted in the delineation of
185 discreet ecological units that make up the Bioregions 2023
framework. The bioregions are built upward using ecoregions as
building blocks but confined tightly within realms and major biome
subdivisions. The bioregions incorporate adjoining freshwater and
marine areas with an average land area of approximately 715,000 km^2.
There are 30 small island bioregions, the smallest being Bermuda,
with only 39 km^2 of land area (not including submerged coastal
areas). The island bioregions are thus mainly delineated by their EEZ
extents. The largest is the massive Siberian Boreal Forests &
Mountain Tundra bioregion, which is 7.7 million km^2 and divided into
three large sections - west, central, and east.
Defining the subrealms
With the full extent of each bioregion established, we can now group
the 185 bioregions into subrealms -- intermediary divisions of the
major realms that cluster bioregions into a more familiar
geographical taxonomy. For example, the "Amazonia" subrealm is
defined as a cluster of 5 tropical forest bioregions roughly
coinciding with the Amazon River basin (note: some consider the
Guianan tropical forests covering French Guiana, Suriname, and Guyana
to be part of the Amazon region, but according to the Ecoregions 2017
framework they are not part of the Amazonian forest complex,
possessing distinct flora and fauna and falling outside of the Amazon
River watershed). Another example of a subrealm is the "Great Plains"
region of North America, which groups together the three major
grasslands bioregions covering the heartland of the US.
Subrealm map - Bioregions 2023
The 52 subrealms of the Bioregions 2023 framework. Download Map (6
MB). Credit: Karl Burkart, One Earth
There are 52 subrealms identified in the One Earth Bioregions 2023
framework. Colors are generated from the dominant bioregions
contained within each subrealm as follows:
* Subarctic America -- Greenland (cyan), Canadian Tundra (blue),
Alaska (indigo), Canadian Boreal Forests (purple)
* Northern America -- North Pacific Coast (blue-green), American
West (brown), Great Plains (gold), Northeast American Forests
(green), Southeast US Savannas & Forests (orange), Mexican
Drylands (olive)
* Central America & Caribbean -- Central America (light green),
Caribbean (green)
* Southern America -- Upper South America (pale green), Amazonia
(deep green), Brazil Cerrado & Atlantic Coast (tan), South
American Grasslands (yellow), Andes Mountains & Pacific Coast
(dark green)
* Oceania -- Oceanic Islands (green)
* Afrotropics -- Madagascar & East African Coast (bright green),
Southern Afrotropics (rust), Sub-Equatorial Afrotropics (orange),
Equatorial Afrotropics (emerald green), Sub-Saharan Afrotropics
(tan)
* South Eurasia -- North Africa (red-orange), Greater Arabian
Peninsula (beige)
* West Eurasia -- Mediterranean (red), Black Sea Forests & Steppe
(gold), European Mountain Forests (dark green), Greater European
Forests (green), British Isles (emerald green)
* Subarctic Eurasia -- Palearctic Tundra (teal), Scandinavia &
Western Boreal Forests (purple), Siberia & Eastern Boreal Forests
(plum), Sea of Okhotsk & Bering Tundra/Taiga (lavender)
* East Eurasia -- Japanese Islands (dark green), Northeast Asian
Forests (grey-green), Mongolian Grasslands (yellow), Central East
Asian Forests (pale green), Tibetan Plateau (tan), East Asian
Deserts (red-brown)
* Central Eurasia -- Kazakh Steppes & Hemiboreal Forests
(chartreuse), Caspian Sea & Central Asian Deserts (brown), Tien
Shan Mountains (tan), Persian Deserts & Forests (dark red),
Altai-Sayan Mountains (olive green)
* Indomalaya -- Indian Subcontinent (light green), Southeast Asian
Forests (emerald green), Malaysia & Western Indonesia (dark
green)
* Australasia -- Australasian Islands & Eastern Indonesia (olive
green), Australia (red), New Zealand (green)
* Antarctica -- Antarctic Continent & Islands (not shown)
You can explore each of the links above to learn more details about
bioregion groupings within the 52 subrealms, the unique
characteristics of all 185 bioregions, and the plant and animal
assemblages contained within each of the 844 component ecoregions
that make up One Earth's Bioregions 2023 framework.
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