Dry Face of the ‘Wet Hemisphere’: Southern Deserts and Semideserts

Abstract

Despite being dominated by Oceans, the Southern Hemisphere has extensive and oldest hot arid ecosystems. These ecosystems are classified as members of the zonobiome S2. South America’s Atacama Desert and Southern African Namib Desert have been subject to intensive scientific enquiry for a long time. Besides the true deserts, iconic semideserts such as Monte (South America), Karoo (Southern Africa), and the Australian Mulga are well-researched too. There is a bioclimatically heterogeneous group of ‘arid thickets’ and localised coastal semideserts (known to German literature as ‘Passatwüsten’), which attracted some attention from ecologists, biogeographers, and conservation biologists. However, they remained poorly understood from the point of view of the biome assignment. Among those rank Chaco and Espinal (South America) and Albany Thickets (South Africa)—all of ecotonal nature. Madagascan Thorny Thickets, and a few other insular coastal semideserts, are recognised here as ‘Passatwüsten’—ecosystems under the influence of desiccating trade wind systems. The classification of the zonobiome S2 into global biomes follows two fundamental splits: desert versus semidesert and coastal versus inland.