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 to the FAO GEZ is straightforward. In other cases, a more thorough study of mapping criteria, including physiognomy, phenology, floristics and dynamics of vegetation types, was needed to establish the correspondence. An additional benefit of using the existing country/regional maps is that they could form the basis or provide supporting information for more detailed regional ecological zoning beyond FRA 2000.
The country/regional vegetation maps also helped in harmonisation of Ecological Zone boundaries across countries or regions. The experts attending the Cambridge expert consultation contributed in a major way to define Ecological Zones of their respective regions as well as in edge matching between adjoining geographic regions.
The following steps were applied to define and map the FAO global Ecological Zones region by region. They are divided in conceptual, thematic issues and technical production steps.
Collection and study of relevant maps and information: suitable regional/national maps of climate, potential vegetation or ecoregions were searched and studied. The ideal maps show distribution and zonation of (potential) natural vegetation and have supporting documentation with details on classification system and criteria. Other important (map) attributes are floristic information, climate and landform or physiography. Depending on regions, the scale of maps was usually smaller than 1 million and both paper and digital versions of the maps were obtained. A first step in the selection of source map(s) was to identify and delineate the Köppen-Trewartha climate types occurring in the country or region (see Figure 30 and Table 1), which are the approximate boundaries of FAO GEZ Level 2. This was followed by an in-depth study of the ecological – and /or vegetation maps, focusing on classification principles and - criteria used, to select the input map(s) for generating the global EZ map. Consultation with regional experts, i.e. authors of maps and publications, was vital in this process. A reference list was made of all source data used.
Matching or aggregating national/regional classes into the FAO GEZ. Based on the in-depth study the relation between national/regional source classes, vegetation types, ecoregions etc. and the Level 2 global Ecological Zones was established. This usually involved aggregation of a number of regional classes into one GEZ. Then an “equivalence “ or look-up table for the region was produced, showing the correspondence between the regional classes and the global Ecological Zones Level 1 and 2, together with documentation and explanation of the matching for review and evaluation purposes. This includes the description and definition of the regional vegetation types or – ecosystems.
Both the existing FRA1990 ecofloristic zone maps and several existing regional maps have been produced using ESRI Arc/Info GIS software system. Thus, it was convenient for the rest of the work to be conducted on Arc/Info, or at least Arc/Info importable. After study of the digital map in the Arc/Info coverage environment and making sure the digital version has appropriate attributes for the polygons, the coverage was edited and attributes for each FAO GEZ levels (1 and 2) were added.
Regarding polygon edge-matching problems along country and regional boundaries, two related causes occurred. One was due to mismatch of polygon definition translations between polygons of both sides, as stated earlier. This problem was generally easy to solve by going back to the original maps and making sure the translation is correct. The other cause is due to offset of lines of the polygons on both sides, even though they may have the same labels. For this problem, we edited manually the coverage and change locations of the lines. This sometimes required more ancillary data and maps such as: composite of NOAA AVHRR spectral bands, classified continental-scale land cover (such as the USGS global land cover database) and digital elevation model (DEM) data.
The resulting output from a regional GEZ production includes the following: Arc/Info coverage of EZ map with attributes of each EZ levels, graphics (e.g. GIF images) of the two levels of EZ, a table containing the levels of EZ and corresponding labels or codes of the input regional maps. For these output materials, see the results by region.
From the perspective of GEZ production, there were some obstacles that affected the progress of producing regional and ultimately global GEZ.
Availability of suitable regional/national maps. For some regions or countries, maps may not exist that have suitable scale, information content, or quality. It is also possible that some regions have paper maps but not their digital version. One solution was to use as an alternative the few available global-scale maps, such as the Terrestrial Ecoregions of the World map (WWF 2000) in combination with a climate map based on Köppen.
Edge matching of cross-boundary polygons. Two sticking points that had to be solved: 1) it was more complicated when different classification principles had been used for the two bordering maps and 2) manual editing was sometimes necessary and is not elegant.
Following the classification and guidelines outlined above, the global map was compiled through a region by region approach. The case studies on North America and South America provided useful experiences and guidelines for GEZ mapping in other regions. In the implementation of the work, regional experts actively participated or were consulted. EDC was responsible for producing the EZ maps for the temperate and boreal regions and jointly with FAO compiled the global map and database, while LET, Toulouse produced the EZ maps for the tropical regions, i.e. South America, Africa and Asia. FAO - FRA2000 provided overall technical and conceptual guidance. After the Cambridge meeting, July 1999, it took one year to produce a draft global map. The draft EZ map was reviewed at a meeting in Salt Lake City (5-7 July 2000) and the final map and database were completed by October 2000.
Regional division and collaborating institutions in the work were as follows:
Region |
Main partners and collaborators |
North - and Central America |
US Forest Service, USA Canadian Forest Service, Canada Institute of Geography, University of Mexico, Mexico Tropical Science Center, Costa Rica |
Europe |
Federal Agency for Nature Conservation, Germany |
Former USSR |
IIASA, Austria Biogeography Department, Moscow State University, Russian Federation |
China |
IRSA, Chinese Academy of Sciences, China |
Middle East |
Damascus University, Syria |
Australia |
Bureau of Rural Sciences, Australia |
Tropics |
LET, France |
