USE OF GEOGRAPHICAL INFORMATION-SYSTEMS IN THE SEARCH FOR ADDITIONAL POPULATIONS, OR SITES SUITABLE FOR REESTABLISHMENT, OF THE ENDANGERED NORTHERN PROVINCE ENDEMIC EUPHORBIA-CLIVICOLA

Euphorbia clivicola R.A. Dyer, an endangered Northern Province endemic , is restricted to only two known populations, both of which are threa tened with extinction. The area between and surrounding the known popu lations, totalling 8874 km(2), was therefore searched for sites where either unknown populations could exist, or which could represent a sui table habitat for the introduction of a new population. A raster-based Geographical Information Systems package, IDRISI for Windows, was uti lized to manipulate two point vector files, representing rainfall and altitude of the searched area, digitized within the TOSCANELLI system. The lNTERPOL module produced two digital elevation models, from which the SURFACE module created slope and aspect images representative of the searched area. RECLASS and OVERLAY modules were finally utilized t o identify 12 potential sites, covering only 1.4% of the total searche d area. Ground-truthing is now needed to determine the presence or abs ence of further populations and to assess habitat suitability. This st udy emphasizes an additional application of GIS techniques to investig ations with relevance to the biological sciences, specifically to prob lems of rare and threatened species. GIS represents a cost-effective a lternative method for addressing these problems by focusing ground sea rching activities to only a small number of potential sites.