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University of Pretoria (1999)

A phytosociological synthesis of Acacia tortilis communities in the north-western savanna of South Africa

Winterbach R

Titre : A phytosociological synthesis of Acacia tortilis communities in the north-western savanna of South Africa

Auteur : Winterbach R

Université de soutenance : University of Pretoria

Grade : Master of science (MS) 1999

Résumé
Aims to compile a phytosociological and synecological synthesis of the vegetation of the Central Savanna, including all phytosociological data collected by various researchers in the study area. This is done in order to identify the major zonal vegetation types that represent phytosociological classes, A hierarchical syntaxonomy has been constructed for one of the classes and the plant communities of this class are formally described according to the code for syntaxonomic nomenclature. The Central Savanna of South Africa can be defined as the bushveld of the North West Province (north of the Magaliesberg) and the Northern Province. The area is situated between the Kalahari in the west (the Botswana border) and the Lowveld, east of the Escarpment. The central part of this area lies within the Transvaal Plateau Basin. This major physiographic region comprises the Bushveld Basin, surrounded by ridges and valleys called the Bankenveld, and to the north the Waterberg, Soutpansberg and Pietersburg plateaux. The various vegetation studies that have been done in the Central Savanna have resulted in many phytosociological tables and descriptions of numerous plant communities. From the results it seems that the Central Savanna may be divided into four major vegetation types, representing phytosociological classes : the ’Commiphoro mollis-Colophospermetea mopani’, the ’Panico maximi-Acacietea tortilis’, the ’Terminalio sericeae-Combretetea apiculati’ and the ’Englerophyto malalismontani-Acacietea caffrae’. The results of the TWINSPAN classification (Hill 1979) indicate that the Mountain Bushveld is a separate, very diverse vegetation type with many different communities. It may be interpreted that the Arid Sweet Bushveld could be divided into two distinct vegetation types. One type has an affinity with Mopane veld, suggesting a distinct sub-class, and the other has an affinity with the ’Panico maximi-Acacietea tortilis’. A hierarchical syntaxonomy has been derived for the ’Panico maximi-Acacietea tortilis’. Two subclasses, four orders, 10 alliances and 36 associations have been identified of which two subclasses, three orders, eight alliances and 15 associations are newly described. This is the first attempt to identify phytosociological classes for the South African savanna from phytosociological releve data.

Présentation (NRF)

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