Calculation of range territories by GIS intersections < Species diversity maps > Comparing geographic data from different sources

4.4.2 — Species diversity maps

Based on the imported species-territory list of mapped mammals and birds, it is possible to calculate the number of migratory species per province. The resulting distribution of diversity is shown in Figure A2.86). A striking result is the high diversity of migrants in temperate regions and coastal areas. There is no increase of diversity towards the tropics such as is frequently noted for other diversity distribution maps on a global scale (see for example Barthlott et al. 1999 for plant diversity). However, administrative units differ tremendously in area, ranging from huge provinces comprising several million square kilometres such as Yakutia (Russia), down to small islands of the Maldives. To compensate for area effects, the intersection of all species maps was repeated with an equal area grid, by using a 200x200 kilometre polygon file with numbered cells.47 The calculation of species numbers per cell led to the diversity distribution shown in Figure A2.87 and coincides qualitatively with the pattern shown in Figure A2.86. Besides coastal areas, highest diversity is observed within areas used by different species for breeding and wintering, often from different biogeographical regions (e.g. Western Asia, North-western Europe. These maps will certainly change when more species are added, in particular the lesser known inner-tropical migrants and passerine birds. But it is evident that a high diversity of migrants can be found within the highly industrialised countries, which may call into question the current focus of conservation efforts on "biodiversity hotspots" in the tropics (cf. Myers et al. 2000).

The procedures outlined above provide the basic data set to answer the seemingly simple question "which species occur in a certain area?". In a GIS, this question can only be answered by querying the composite, merged maps ("allpolygon.shp"), which is a time-consuming operation. But once the resulting species lists have been entered into the database, simple SQL-statements are sufficient to produce approximate, but highly useful results. The user can produce species lists for certain territories, sites, or any "area of interest" delimited by geographic co-ordinates (see "selection by bounding box" in the GROMS database), or interactively by our JAVA map server ( The user can generate a rectangle on a map, and search for all species occurring within this area of interest. Further details about the underlying data model and software are explained in Figure 3.5, the User Guide (Annex I), and Riede 2001.

The applications for geographic searches are manifold. Users can retrieve species lists for a province of their interest, and compare the results with their own data. In case of environmental catastrophes or planned major development projects, the "affected" species can be identified quickly (Table 4.13). However, the user should always keep in mind that the resulting GROMS list is still incomplete, because it is limited to the 544 species mapped, and to the site-specific lists entered up to now. The GROMS information desk on the World Wide Web will be updated constantly with additional geographic information, and the actual list of species mapped can be queried there (

47 Note that this operation makes polygon maps comparable with raster maps, and vice versa.
Calculation of range territories by GIS intersections < Species diversity maps > Comparing geographic data from different sources

This document should be quoted as part of the publication "Riede, K. (2001): The Global Register of Migratory Species ­ Database, GIS Maps and Threat Analysis. Münster (Landwirtschaftsverlag), 400 pp." + CD

 by Klaus Riede