Appendix D: Comparison of Ecoregion
and Related Approaches
This appendix provides relevant information
about the currently available climatic, biotic,
and ecological regionalization maps that cover
the whole globe or large parts of it. An account of
the relationship between climate and vegetation,
and the theory behind defining ecological zones,
or ecoregions, is given in the main text of this
book. Olstad (2012) reviews the concepts and
uses of ecoregions and the process of ecoregionalization to illustrate the traditions and
philosophies within the discipline of geography.
Ecoregions for environmental management is the
subject of a special issue of Environmental Management (Loveland 2004). The ecoregions collection of the Encyclopedia of Earth (Cleveland
2011) holds the results from several of the most
widely used systems to delineate ecoregions.
The global maps described below primarily
define climatic ecological zones. Some of them,
such as the World Wildlife Fund (WWF) maps,
emphasize differences in biogeography or species origins. Some regional and national maps
also emphasize the biogeographical/phylogenetic aspect. Other maps are empirical in that
they are based on cluster analysis of data or
overlay of thematic maps to identify relative
homogeneous areas. But before we review the
various ecological regionalization maps, we
look first at other related approaches.
Ecoregions Versus Other Land
Divisions
Contrasting other land-division categories such as
physiographic regions and biotic areas (also
called “biotic provinces” or “bioregions”),
ecoregions are based on both biotic and abiotic
features. A geologist might look at a given area in
terms only of geologic formations and structures.
In fact, a geologist produced one of the bestknown physiographic maps of the United States
with this perspective (Fenneman 1928). Where
major physiographic discontinuities occur—
where mountains meet plains, or where igneous
rock ends and sedimentary rock begins—the
boundaries often coincide with changes in the
biota; quite simply: changes in the land can correlate to changes in flora and its associated fauna. In
areas of little relief, such as the Great Plains, little
or no correlation exists between the geologist’s
concept of physiography and the biologist’s concept of ecology.
A biologist (c.f. Dice 1943) might examine the
same area as the geologist but in terms of the
biota’s spatial patterns. Large, relatively homogeneous units of biota at the regional scale are
known as biomes (Clements and Shelford 1939;
Brown et al. 1998). Heinrich Walter (1984) refers
to these as zonobiomes because they are based on
large climatic zones. Subdivisions of biomes
have been mapped by Miklos Udvardy (1975)
after work started by Raymond Dasmann
(1972); these subdivisions are called “biogeographic provinces.” However, biota constantly
changes due to disturbance and succession. For
example, either fire or timber harvesting may
destroy a forest causing flora-specific fauna either
to emigrate or to perish; either outcome produces
a profound but temporary absence. As the succession process restores the forest to predisturbance
conditions, most if not all of the fauna will repopulate the forest, though it will do so at varying
rates according to species. Additionally but quite
R.G. Bailey, Ecoregions, DOI 10.1007/978-1-4939-0524-9, # Springer Science+Media, LLC 2014
147
and Related Approaches
This appendix provides relevant information
about the currently available climatic, biotic,
and ecological regionalization maps that cover
the whole globe or large parts of it. An account of
the relationship between climate and vegetation,
and the theory behind defining ecological zones,
or ecoregions, is given in the main text of this
book. Olstad (2012) reviews the concepts and
uses of ecoregions and the process of ecoregionalization to illustrate the traditions and
philosophies within the discipline of geography.
Ecoregions for environmental management is the
subject of a special issue of Environmental Management (Loveland 2004). The ecoregions collection of the Encyclopedia of Earth (Cleveland
2011) holds the results from several of the most
widely used systems to delineate ecoregions.
The global maps described below primarily
define climatic ecological zones. Some of them,
such as the World Wildlife Fund (WWF) maps,
emphasize differences in biogeography or species origins. Some regional and national maps
also emphasize the biogeographical/phylogenetic aspect. Other maps are empirical in that
they are based on cluster analysis of data or
overlay of thematic maps to identify relative
homogeneous areas. But before we review the
various ecological regionalization maps, we
look first at other related approaches.
Ecoregions Versus Other Land
Divisions
Contrasting other land-division categories such as
physiographic regions and biotic areas (also
called “biotic provinces” or “bioregions”),
ecoregions are based on both biotic and abiotic
features. A geologist might look at a given area in
terms only of geologic formations and structures.
In fact, a geologist produced one of the bestknown physiographic maps of the United States
with this perspective (Fenneman 1928). Where
major physiographic discontinuities occur—
where mountains meet plains, or where igneous
rock ends and sedimentary rock begins—the
boundaries often coincide with changes in the
biota; quite simply: changes in the land can correlate to changes in flora and its associated fauna. In
areas of little relief, such as the Great Plains, little
or no correlation exists between the geologist’s
concept of physiography and the biologist’s concept of ecology.
A biologist (c.f. Dice 1943) might examine the
same area as the geologist but in terms of the
biota’s spatial patterns. Large, relatively homogeneous units of biota at the regional scale are
known as biomes (Clements and Shelford 1939;
Brown et al. 1998). Heinrich Walter (1984) refers
to these as zonobiomes because they are based on
large climatic zones. Subdivisions of biomes
have been mapped by Miklos Udvardy (1975)
after work started by Raymond Dasmann
(1972); these subdivisions are called “biogeographic provinces.” However, biota constantly
changes due to disturbance and succession. For
example, either fire or timber harvesting may
destroy a forest causing flora-specific fauna either
to emigrate or to perish; either outcome produces
a profound but temporary absence. As the succession process restores the forest to predisturbance
conditions, most if not all of the fauna will repopulate the forest, though it will do so at varying
rates according to species. Additionally but quite
R.G. Bailey, Ecoregions, DOI 10.1007/978-1-4939-0524-9, # Springer Science+Media, LLC 2014
147