Argentine Pampas

Melanization is well expressed under grassland vegetation growing in a continental climate characterized by cold, dry winters, moist springs, and dry summers punctuated by thunderstorms. These conditions are typical for the steppe of Ukraine where the annual precipitation is about 450 mm and the mean temperatures for the coldest and warmest months are —7°C and 21.5° C respectively (Joffe, 1949 Duchaufour, 1978). Similar conditions exist in the Great Plains of North America and Eastern Europe. Melanization also occurs in the Argentine pampas where the winters are milder and the summers less dry than in continental North America and Eurasia. Soils developed under these conditions display a thick A horizon, i.e. dark, well structured and full of roots. The B horizon may be poorly developed, while the C horizon may contain soft concretions of CaC03 (Fig. 7-4). 

The Junin virus that causes Argentine hemorrhagic fever is carried by a field mouse, Calomys colosus, and is associated with agricultural activities in the pampas of Argentina, where 300 to 600 cases have occurred every year since 1955.2 In Bo-... 

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