Plant Communities on a Granitic Outcrop

Abstract

The term ‘inselberg’, proposed by Bonhardt (1900), characterises isolated rock outcrops consisting mainly of Precambrian granites or gneisses. The origin, geology and geomorphology of inselbergs have been widely studied (Bremer & Jennings 1978, Twidale & Bourne 1978, Twidale 1980). In South America, classical whale back forms dominate and are scattered throughout the Guiana and Brazilian Shield up to East Bolivia. These hills rise abruptly from the surrounding landscape and constitute singular habitats in tropical rain forest. Due to the poorly developed soils and extreme microclimatic fluctuations, they are colonised by vegetation drastically different from the surroundings. Thus, they reflect a clear habitat fragmentation and constitute functional ‘terrestrial’ islands (Prance 1996).