Nicola Arndt und Matthias Pohl - Neobiota

3.3 FAO Global Ecological Zone classification system
FAO’s global Ecological Zone classification (Table 1) relies on a combination of climate and
(potential) natural vegetation. The following summarizes the classification criteria and principles of
the system:
• The Köppen-Trewartha climatic groups and climatic types, with modifications adopted at the
Cambridge workshop, are the first two levels of a hierarchical FAO global Ecological Zone
classification system. At the broadest level, equivalent to Köppen-Trewartha’s climatic groups,
five domains are distinguished based on temperature: Tropical, Subtropical, Temperate, Boreal,
Polar.
• At the second level, 20 classes or Ecological Zones are distinguished using precipitation as
additional criterion. Within each domain a zone of mountain systems is distinguished at level 2.
The Ecological Zones reflect broad zones of relatively homogeneous vegetation, such as tropical
rainforest, tropical dry forest, boreal coniferous forest, etc. Typical azonal vegetation types, for
instance mangroves, heath and swamps are not separately classified and mapped. Mountain
systems usually contain a variety of vegetation types, and include forests, subalpine scrub, alpine
grasslands and bare rock. The current global framework cannot address the high, mostly smallscale
diversity of mountain habitats. The polar domain is not further subdivided, as it is treeless,
and only very sparse shrub or grass vegetation occurs locally. Here the second level is equivalent
to the first.
• The second level, of 20 classes, is the reference or working level for the global Ecological Zone
mapping 6 . The names of the global Ecological Zones reflect the dominant zonal vegetation.
A main principle in delineating the global Ecological Zones involves aggregating or matching regional
ecological or potential natural vegetation maps into the global framework. The following steps can be
distinguished (the practical implementation is described in Part II):
1. Identification of Köppen-Trewartha climatic types and mountains occurring in a region,
which will approximate the level 2 Ecological Zone class of the FAO scheme.
2. Establishment of correspondence between regional/national potential natural vegetation
types and the global Ecological Zones.
3. Final definition and delineation of the global Ecological Zones, using the maps and source
data consulted in steps 1 and 2 7 .
4. Edgematching between adjacent maps.
5. Validation.
4 Development of the map and results
4.1 Use of regional source maps and expertise
To ensure the best use of regional knowledge and information, existing regional/national maps on
vegetation, biogeography, ecology and climate were used to generate the GEZ map. In some cases,
such as the USA, the classification is based on the Köppen-Trewartha climate system and translation
6 A more detailed regional classification system similar to that carried out for FRA 1990 may be conducted for
regions. Concept and principles for more detailed schemes that use elevation and other parameters had been
discussed during the Cambridge Expert meeting, July 1999 (see FAO 2000).
7
For this part of the work, FAO has relied heavily on the advice of regional experts specialized in ecological
zoning and mapping.
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