An Introduction to Mountains - Mountain Geography: Physical and Human Dimensions - page 8

good basis for delimiting high mountain environments. “According to this concept, high
mountains are mountains which reach such altitudes that they offer landforms, plant
cover, soil processes, and landscape character which in the classical region of mountain
geography in the Alps is generally perceived as high-alpine” (Troll 1972: 4).
All of these approaches to defining mountains rely on a detailed analysis of one or
more factors, usually based on fieldwork, ground-based topographic mapping, or both.
More recently, modern technologies based on remote sensing have been applied to the
definition of mountains at both regional and global scales. In 1996, the U.S. Geological
Survey completed its GTOPO30 global digital elevation model. With a horizontal grid
spacing of 30 arc seconds, the altitude of every square kilometer of the Earth's land
surface was recorded in a database which could be used to derive a detailed typology of
mountains based on not only altitude but also slope and terrain roughness (local elev-
ation range, LER). Kapos et al. (2000) iteratively combined parameters from GTOPO30
to develop such a typology, starting from first principles and in consultation with scient-
ists, policymakers, and mountaineers. First, 2,500 m, the threshold above which human
physiology is affected by oxygen depletion, was defined as a limit above which all en-
vironments would be considered “mountain.” Second, they considered that at middle
elevations, some slope was necessary for terrain to be defined as “mountain,” and that
slopes should be steeper at lower elevations. Finally, to include low-elevation moun-
tains, the LER was evaluated for a 7-km radius around each target cell: If the LER was
at least 300 m, the cell was defined as “mountain.” According to this typology, 35.8 mil-
lion km 2 (24 percent of global land area) was classified as mountainous (Table 1.1; Fig.
1.1).
A further statistic of equal relevance is the global population in mountain areas,
long estimated at about 10 percent (Ives and Messerli 1997). Using the mountain area
defined by Kapos and others (2000), Huddleston and others (2003) estimated this to be
approximately 720 million people (12 percent of the global population). Meybeck and
others (2001), using an aggregated version of GTOPO30, also estimated that 26 per-
cent of the global population live within or very close to mountain areas. Thus, with
about a quarter of the Earth's land surface covered by mountains, and about a quarter
of the global population living in or near them, mountain issues clearly have an import-
ant place on the global development and environment stage. Hence, mountains are on
political agendas, and we should note that the definition of mountains is also a political
process. For instance, decisions regarding the extent of mountains in Europe are closely
linked to the availability of subsidies for mountain farmers (Price et al. 2004).
In summary, a universally accepted definition of what a mountain is will always re-
main elusive. For our purposes, however, a mountain can be defined as a conspicuous,
elevated landform of high relative relief. Much of its surface has steep slopes, and it
displays distinct variations in climate and vegetation zones from its base to its summit.
A high mountain landscape is the area above the climatic timberline where glaciation,
frost action, and mass wasting are dominant processes. Additionally, a landform is con-
sidered a mountain when local people rate it as such because it plays an important role
in their cultural, spiritual, and working lives.
Mountain Challenges and Opportunities