Oecologia (2013) 171:335–337
DOI 10.1007/s00442-012-2416-7
VIEWS AND COMMENTS
On the use of elevation, altitude, and height in the ecological
and climatological literature
Tim R. McVicar • Christian Körner
Received: 28 June 2012 / Accepted: 2 July 2012 / Published online: 18 August 2012
Ó Springer-Verlag 2012
Abstract Effective communication regarding distance in
the vertical dimension is critical for many ecological, climatological and broader geophysical studies of the Earth.
Confusion exists regarding the definition of three English
words commonly used to describe the vertical dimension:
(1) elevation; (2) altitude; and (3) height. While used
interchangeably in ‘‘everyday’’ non-technical English, here
we provide explicit definitions and strongly recommend
their use in scientific literature. We briefly discuss the
likely origins of the sub-optimal use of these three words
due to translations between languages. Finally, we provide
examples of how using these terms, as explicitly defined
herein, improves scientific communication.
Keywords
Elevation Altitude Height Lapse rate
In this short note, we define three English words that are
commonly used to describe the vertical dimension for use
in the ecological, climatological, and broader geophysical
sciences. In most ecological and climatological scientific
Communicated by Russell Monson.
Electronic supplementary material The online version of this
article (doi:10.1007/s00442-012-2416-7) contains supplementary
material, which is available to authorized users.
T. R. McVicar (&)
CSIRO Land and Water, GPO Box 1666,
Canberra, ACT 2601, Australia
e-mail: [email protected]
C. Körner
Institute of Botany, University of Basel,
Schönbeinstrasse 6, 4056 Basel, Switzerland
studies, and for many geophysical sciences, measurements
and models are implicitly conducted in a four-dimensional
framework: here denoted x, y, z, and t. With x and y referring to the horizontal coordinates (a common approach that
is used in many Cartesian plots and associated with a
planar view of the Earth’s surface), z refers to the vertical
dimension (either above or below a reference point), and
t refers to time from some other reference point. This short
note primarily addresses z and aims to clarify the meaning
of three English words commonly used to describe a
positive z. They are: (1) elevation; (2) altitude; and (3)
height. As these terms are used interchangeably in
‘‘everyday’’ English, and because many other languages do
not have the same granularity of definition as English, there
is now widespread misuse of these terms in the ecological
and climatological literature published in English. To
encourage the correct use of these terms, we now provide
explicit definitions in English that are suitable for use by
the ecological, climatological, and geophysical sciences.
Elevation is the vertical distance between a point on the
land surface and a reference point, usually taken to be the
mean sea level.
Altitude is the vertical distance between an object (e.g.,
a bird, aircraft, or parcel of air) and a reference point or
stratum, where the object is not in direct contact with the
reference point/stratum. The reference point/stratum is
usually either the mean sea level (e.g., as often used by
commercial airlines) or the land surface (at whatever elevation), which is often used when describing the altitude of
a parcel of air, for example.
Height is the vertical distance between (usually) the top
of an object (e.g., a tree, building, person, or Stevenson
screen) and the land surface, where the object is in direct
contact with the ground. It is therefore a measure of how
far something vertically protrudes above the land surface.
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As an aid to understanding the difference between the
English words ‘‘elevation’’ and ‘‘altitude,’’ consider a
digital representation (often a raster) of the land surface.
Such a representation is often called a ‘‘digital elevation
model’’ (DEM), and sometimes a ‘‘digital terrain model;’’
in English it is never termed a ‘‘digital altitude model!’’
DEMs are used widely in the ecological (e.g., Elith and
Burgman 2003; Guisan et al. 2006; Guisan and Zimmermann 2000; McVicar et al. 2010a), climatological (e.g.,
Daly 2006; McVicar et al. 2007, 2010b), hydrological (e.g.,
Moore et al. 1991; Western et al. 1999), and soil (e.g.,
McBratney et al. 2003; McKenzie and Ryan 1999) sciences. They provide a direct measure of the elevation of the
land surface (hence the name), and many topographic
measures (see Wilson and Gallant 2000, and the references
therein) such as slope, aspect, contributing area, hypsometric curves, and relative elevation that are useful in the
ecological and climatological sciences can be derived from
a DEM.
In the ecological and climatological scientific literature
(and in other geophysical sciences) written in English, the
term ‘‘altitude’’ is often incorrectly used to convey the
meaning of increasing elevation in a mountain range.
Some papers sub-optimally refer to an ‘‘altitudinal gradient’’ (e.g., Bonin et al. 2006; Ghalambor et al. 2006;
Inouye et al. 2000; Kitayama 1992; Körner 2007) when
describing: (1) resource gradients; and/or (2) species
composition and abundance. However, many of these
studies should correctly be referring to an ‘‘elevational
gradient,’’ a term that has been used by many when dealing
with this topic (e.g., Bryant et al. 2008; Choler et al. 2001;
Colwell et al. 2008; Moritz et al. 2008; Nogués-Bravo
et al. 2008; Turner and Romme 1994; Wilson et al. 2007).
If additional components that are used to describe landscape topography (e.g., slope and aspect) are important
when defining the resource gradients and/or species composition and abundance, then the term ‘‘topographic gradient’’ should be used. In many ecological studies that deal
with the land surface or features connected with it, the
term ‘‘elevational gradient’’ (or ‘‘topographic gradient,’’
noting that topography is a function of slope, aspect, and
elevation) should be used in preference to the term ‘‘altitudinal gradient.’’
The misuse of the English term ‘‘altitude’’ likely derives
from sub-optimal translations performed among the English, German, French, and other Romanic languages in the
nineteenth and early-to-mid twentieth centuries, when
material published in these languages heavily influenced
relevant scientific progress. While only a single German
word, ‘‘Höhe,’’ is primarily used for all three English terms
(see Table S1 of the ‘‘Electronic supplementary material,’’
ESM), there are several terms in the Romanic languages
that are similar in form to the English words ‘‘elevation,’’
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Oecologia (2013) 171:335–337
‘‘altitude,’’ and ‘‘height’’ but have different meanings. To
assist, we provide: (1) a brief discussion of translations of
the English terms ‘‘elevation,’’ ‘‘altitude,’’ and ‘‘height’’
into several of the key Romanic languages (see ESM S1);
and (2), following consultation with over 60 scientists,
translations of these three English words into over 30
languages (see Table S1).
As scientific papers and concepts were translated
between languages there was ample opportunity for erroneous translations that did not fully capture the English
language definitions of these three terms to occur. With the
increasing use of English to document and report scientific
progress in the last 60 years (i.e., in the latter half of the
twentieth century and beyond), it is important that such
terms are explicitly defined. The correct use of such
explicitly defined terms is important as, at the very least,
it readily conveys complex scientific meaning—most
importantly, it can avoid misinterpretation. For example,
compare the term ‘‘environmental lapse rate,’’ which deals
with changes as a function of elevation, with the term
‘‘process (or free-air) lapse rate,’’ which deals with changes
as a function of altitude. This example clearly illustrates
the advantage of using explicitly defined terms to describe
the vertical dimension.
While the differences in the definitions of elevation,
altitude, and height may appear subtle, such differences are
an important part of the framework of scientific communication. Key framework concepts are critical to scientific
advancement and communication. In this vein, when
dealing with the fourth dimension, t, we implore readers to
note the difference between: (1) Julian day (which is
widely used in astronomy, with the current 7,980 year
cycle starting at noon GMT on 1st January 4,713 B.C., and
which does not reset to 1 on the 1st January each year); and
(2) the day-of-year concept (which resets to 1 on the 1st
January each year).
Similarly, correct symbology is also important. For
instance, absolute temperature is measured in kelvins,
which has been assigned the symbol K (not °K; this
notation was abolished at the 13th Conférence Générale
des Poids et Mesures held in 1967 in Paris, as the degree
symbol usually suggests a relative framework of measurement). On the other hand, the symbol for degrees
Celsius is °C, as this is a relative measure of temperature
(there is an offset of 273.16 between these relative and
absolute measurement systems). When discussing temperature differences (such as between day and night, between
microhabitats, or in freezing resistance), the use of K rather
than °C helps to avoid confusion in texts referring to both.
Note that when both symbols are used with the correct
symbology, there is no conflict regarding the consistent use
of dimensions, as a temperature change of 1 K is exactly a
temperature change of 1 °C.
Oecologia (2013) 171:335–337
Acknowledgments We thank the many scientists listed in Table S1
of the ESM who provided translations for this comment. A note by
Hal Mooney, Stanford University, to C.K. encouraged us to address
this issue.
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