4.4.6 — Perspectives for geographic analysis

On a global level, the WWF has compiled a map of ecoregions in GIS format (available as wwf_eco.shp within ArcView 3.2, ESRI), which includes threat categories from 1 (= Critical) to 5 (= Relatively Intact). Most parts of Eurasia qualify as "Critical" or "Endangered". However, large parts of the world such as Africa and South America still classify as "Not Assessed or Unknown". From these ecoregions, Dinerstein & Olson (1998) selected "The Global 200", as a representative set of the earth's most biologically valuable ecosystems. Their list includes marine ecoregions, freshwater ecosystems, lakes, large deltas and estuaries, all of which are extremely important for migratory species. However, they are not yet included within wwf_eco.shp. In addition, the WWF map does not contain the habitat conservation status assessment as given by Dinerstein & Olson (1998). Considering these inconsistencies, it is still too early to intersect ecoregion GIS files with maps of migratory species. However, a quick glance at "The Global 200" map shows that most of the ecoregions do not overlap with the high-diversity areas identified by GROMS (Figures A2.86, A2.87). Among the most important ecoregions for migrants are some deserts and xeric shrublands such as the Great Basin shrub steppe (Northern America), the Azerbaijan shrub desert and steppe (Western Asia), or the montane grasslands of the eastern Anatolian montane steppe (Western Asia). None of these ecoregions are included in "The Global 200", and most of them include interspersed wetlands, which are not resolved at the global scale hitherto used. Therefore, it would be important to make a profound GIS analysis of migrants within ecoregions, as soon as fresh data sets at higher resolution are available.

The examples mentioned above are all based on classifications of natural habitats such as would occur without human interference or might re-emerge after human intervention ceases. For instance, Central Europe is indicated on these maps as "broad-leaved temperate forest", i.e. the natural vegetation type and not the type that currently predominates (agricultural steppe, forest plantations). Most regions are severely modified, in the best of cases transformed into agro-ecosystems which at least partially mimic the original ecosystem functionality. Chapin III et al. (2000) review the multiple effects of human activity on biodiversity. On a global scale, "humans have transformed 40-50% of the ice-free land surface, changing prairies, forests and wetlands into agricultural and urban systems. We dominate (directly or indirectly) about one-third of the net primary productivity on land and harvest fish that use 8% of ocean productivity. We use 54% of the available fresh water, with use projected to increase to 70% by 2050" (l.c., p. 234). It is clear that these activities have profound effects on migratory species, but exact predictions are difficult to make. If we want to maintain species outside protected areas, or the few remaining wilderness areas, it is decisive to know the exact distribution and nature of land use. Relevant geodata layer are already available, and include population density and change rates, agriculturally used land, road density or livestock density. Kaps (1999)⁵⁰ discusses possible effects on African species listed in CMS Appendix I, using some of the mentioned data layers. The FAO's Environment and Natural Resources Service (SDRN) carries out a number of activities concerning land cover and land use, most of which apply modern techniques of remote sensing and GIS technology. Examples are the Africover Interpretation and Mapping System, or the development of a Land Cover Classification System (see http://www.fao.org/sd/eidirect/Eire0057.htm). Systematic integration of these data sets into species conservation schemes is still in its infancy.

But even without a GIS, clear conclusions on the catastrophic effects of habitat conversion can be drawn from case studies. The collapse of aquatic warbler (Acrocephalus paludicola) populations correlated clearly with destruction of its marsh and reed habitats (see Figure A2.48). Many more examples are mentioned in the captions in Annex II, and the recent edition of "Threatened Birds of the World" (BirdLife International 2000) is full of further detailed accounts.

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