PhD / Thesis (PhD (Botany and Zoology))—University of Stellenbosch, 2009. / An intriguing biogeographic area that lies in northwestern Namibia and southwest Angola is known
for having numerous endemic taxa. It had, however remained vaguely defined because of the
complex flora, the arid environment and confusing and inconsistent use of biogeographic
terminology. This thesis redefined the area as a centre of endemism based on recurrent patterns of
plant distributions by shared species. The end result is a well-defined entity with regard to, not only
geographic boundaries and floristic elements, but also to its history and floristic relationships.
A vast amount of information on the plants of the area, their affinities and their distributions is
required for a study of this nature and this was undertaken through literature surveys and field work.
All the relevant information on Namibia and the southwestern Angolan flora, i.e. the region and the
study area, were incorporated into a database which formed the bases for numerical analysis and
GIS studies. The database also brought together a wide range of information from literature sources
that included facts and theories about the past and present physical environment. The structure of
the database permitted querying this electronic data in many different ways.
To accommodate the wide variety of subjects in a logical way, the thesis was divided into two
sections. Section A concentrated on the region and provided background information and context.
The theory, terminology and phytogeographic studies in the region were evaluated as a first step. A
large amount and variety of palaeo-environmental and palaeo-ecological information, pertinent to
the region was incorporated. Secondly the flora was assessed. Besides the diversity, distribution
patterns of the plants within and outside the region, including disjunct distributions, phylogenies
were assessment. Finally taxa with similar geographic ranges were grouped. These entities were
mapped and both the taxa and their environments were evaluated
Section B focused on the core area, namely the Kaokoveld Centre of Endemism, which was
delimited by numerical techniques, and then investigated further with regard to its floristic
components, relationships and origins. The flora and endemic components are described in detail.
The result is a well-defined centre of endemism which comprises one endemic family, 10 endemic
genera and nearly 300 endemic species. The flora of the Centre includes about 1600 species in
nearly 550 genera in 130 families. Three floristic Groups, identified in section A, that have a
remarkable number of endemics are found in the Centre. Historical explanations for the distribution
patterns were suggested and the Group that includes Welwitschia mirabilis Hook.f., has been shown
to be linked to the Arid Corridor. The demand for accurate knowledge about biodiversity has been highlighted by the Convention of
Biological Diversity and there are a remarkable number of users with different requirements today.
This study provides a much needed alternate look at the plants of the region, as well as a summation
of the principle phytogeographic elements of the Namibian flora. It also includes a new
phytogeographic classification and map of the floristic Groups of Namibia, which will contribute to
defining floristic areas in the region.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1325 |
| Date | 03 1900 |
| Creators | Craven, Patricia |
| Contributors | Dreyer, L. L., Van Wyk, A. E., University of Stellenbosch. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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