Document: GER-3-82-18

Mapping of species richness and endemism on the continental to global scale using new methodological approaches.

KIER, G.*, J.MUTKE and W.BARTHLOTT

University of Bonn, Germany ¹

Abstract:
Biodiversity maps are an effective means of communicating ecological information. They are often made by adding up the distribution maps of individual taxa ("taxon-based approach"). Two maps are presented which are based on alternative methodological approaches ("inventory-based approaches"). The first one is a world map which displays the number of vascular plant species per 10,000 sq km. On the second map, an index which combines species richness and endemism ("endemism richness", sometimes also referred to as an index of range size rarity) is displayed for the seed plants of the 20 regions of the African continent as delineated by White. The world map of vascular plant species richness is based on the number of vascular plant species occuring in geographical units (e.g., countries, provinces, mountain ranges, deserts) covering all continents. As the geographical units are of different size, their species numbers were standardized to make them comparable by applying the species-area model of Arrhenius. Interpolation techniques were used to estimate species richness of those regions for which species numbers were not known and to differentiate species richness values within larger geographical units. Many essential steps of the methodology used for Barthlott's world map were completely revised, such as the standardization procedure and the interpolation techniques, and the number of geographical units in the data base was enlarged by 80 percent. General results are that all regions with more than 5000 species per 10,000 sq km are located in the humid tropics and subtropics. In some Mediterranean regions, the values reach 3000 to 4000 species per 10,000 sq km. For the map of African seed plant endemism richness, a calculation method was used which was based on the division of the flora of these regions into chorological groups. Minimum values of endemism richness can be observed in the Sahel and Sahara regions, whereas the highest value was calculated for the Cape region, followed by East Madagascar with a considerably lower score. We argue that endemism richness can be regarded as the specific contribution of an area to global biodiversity.

Keywords: species richness, endemism, range-size rarity, conservation value, vascular plants, mapping

This abstract is being presented at: 10:30 AM in session:
Oral Session #2: Conservation Ecology.