scholarly journals Retreat of the Great Escarpment of Madagascar from Geomorphic Analysis and Cosmogenic 10 Be Concentrations

Author(s):  
Y. Wang ◽  
S. D. Willett ◽  
D. Wu ◽  
N. Haghipour ◽  
M. Christl
Keyword(s):  
2021 ◽  
pp. 120368
Author(s):  
Tebogo V. Makhubela ◽  
Jan D. Kramers ◽  
Sibusiso M. Konyana ◽  
Herman S. van Niekerk ◽  
Stephan R. Winkler

Koedoe ◽  
1997 ◽  
Vol 40 (2) ◽  
Author(s):  
C.M. Smit ◽  
G.J. Bredenkamp ◽  
N. Van Rooyen ◽  
A.E. Van Wyk ◽  
J.M. Combrinck

A vegetation survey of the Witbank Nature Reserve, comprising 847 hectares, was conducted. Phytosociological data were used to identify plant communities, as well as to determine alpha and beta diversities. Eleven plant communities were recognised, two of these are subdivided into sub- communities, resulting in 14 vegetation units. These communities represent four main vegetation types, namely grassland, woodland, wetland and disturbed vegetation. Grassland communities have the highest plant diversity and wetland vegetation the lowest. Floristic composition indicates that the vegetation of the Rocky Highveld Grassland has affinities to the grassland and savanna biomes and also to the Afromontane vegetation of the Great Escarpment. An ordination scatter diagram shows the distribution of the 14 plant communities or sub-communities along a soil moisture gradient, as well as along a soil depth/surface rock gradient. The sequence of communities along the soil moisture gradient is used for calculating beta-diversity indices. It is concluded that the relatively small size of the Witbank Nature Reserve is unlikely to have significant negative effects on the phytodiversity of the various plant communities. This nature reserve is therefore of considerable importance in conserving a representative sample of the Rocky Highveld Grassland.


Bothalia ◽  
2021 ◽  
Vol 51 (2) ◽  
Author(s):  
Ben Strohbach

Background: The Great Escarpment of southern Africa takes the form of an extended mountainous highland in central-western Namibia, commonly referred to as the ‘Khomas Hochland’. It is regarded as an area of high botanical diversity. Yet only few localised studies on the vegetation composition are available. The Khomas Hochland is formed on the southern part of the Damara Orogen and dominated by metamorphosed sediments. Climatically it forms a transition between the hot desert of the Namib and the slightly cooler hot steppe in the inland.Objectives: To classify and provide syntaxonomical descriptions of the vegetation of the Khomas Hochland.Methods: A dataset comprising 1151 relevés and 914 species was compiled from various surveys, mostly collected under, and to the standards of, the umbrella project ‘Vegetation Survey of Namibia’. For first classifications, the data set was reduced to a synusial set consisting of trees, shrubs, dwarf shrubs and grasses only.Results: The classification resulted in four major landscape units, being the Pre-Namib and Escarpment zone, the Khomas Hochland proper, riverine habitats as well as surrounding lowlands. The classification was further refined using Cocktail procedures to produce 30 associations, one with four sub-associations. These are described in this paper.Conclusion: A classification of synoptic data grouped the associations into five orders and one undefined cluster of associations on specialised desert habitats. Four of these orders correspond to the habitat types identified in the first classification. The fifth order, the Senegalio hereroensis–Tarchonanthoetalia camphorathi, represents high mountains of the central Khomas Hochland, which link biogeographically to the grassland biome in South Africa.


Bothalia ◽  
2003 ◽  
Vol 33 (1) ◽  
pp. 53-57 ◽  
Author(s):  
C. L. Bredenkamp ◽  
A. E. Van Wyk

Passerina L. is mainly a southern African genus, comprising 20 species and four subspecies. A few species occur along the Great Escarpment, two extend into Zimbabwe and Mozambique, but most are concentrated in the Cape Floristic Region. Palynological. macromorphological and anatomical evidence was used in the delimitation of the genus and its infrageneric taxa. A cladistic study supports Passerina as a monophyletic genus. A genus treatment, key to species and a full species treatment are given. Each species treatment includes a taxonomic diagnosis, description and notes on taxonomy, etymology, economic value and distribution. Illustrations of representative species are provided and distribution maps are included for each species.  P. esterhuyseniae Bredenk. A.E.van Wyk is newly described. A list of excluded species names highlights the previous cosmopolitan taxonomic interpretation of Passerina. as many names are now in synony my under other genera of the Thymelaeaceae.


2019 ◽  
Vol 189 (3) ◽  
pp. 1046-1066
Author(s):  
Peter John Taylor ◽  
Teresa Kearney ◽  
Desire Lee Dalton ◽  
Gamuchirai Chakona ◽  
Christopher M R Kelly ◽  
...  

Abstract Mitochondrial DNA sequences (1137 bp) of the cytochrome b gene and craniodental and craniometric data were used to investigate the evolutionary relationships of six putative rodent taxa of Otomys (family Muridae: subfamily Murinae: tribe Otomyini) co-occurring in the Western Cape and Eastern Cape provinces of South Africa. Phylogenetic analysis of 20 new sequences together with craniodental and craniometric characters of 94 adult skulls reveal the existence of a unique lineage of Otomys cf. karoensis (named herein Otomys willani sp. nov.) from the Sneeuberg Centre of Floristic Endemism in the southern Drakensberg Mountain Range. Craniometric analysis distinguished O. karoensis from O. willani and identified a further four localities in the range of the latter species. We document southern range extensions of both Sloggett’s ice rat, Otomys sloggetti, and the vlei rat Otomys auratus to the Sneeuberg Mountain Range, in addition to appreciable genetic divergence between Sneeuberg and southern and central Drakensberg populations of O. sloggetti. Our results demonstrate parallel patterns of cryptic speciation in two co-occurring species complexes (Otomys irroratus s.l. and O. karoensis s.l.) associated closely with the boundaries of biomes (fynbos vs. grassland biomes) and geological formations (Cape Fold Belt vs. Great Escarpment).


2014 ◽  
Vol 92 ◽  
pp. 159-174 ◽  
Author(s):  
V.R. Clark ◽  
A.P. Dold ◽  
C. McMaster ◽  
G. McGregor ◽  
C. Bredenkamp ◽  
...  

Phytotaxa ◽  
2019 ◽  
Vol 423 (3) ◽  
pp. 182-186
Author(s):  
GIDEON F. SMITH ◽  
ESTRELA FIGUEIREDO

Although most species of Aloe Linnaeus (1753: 319) flower in winter, the comparatively few taxa of this genus that occur naturally above South Africa’s climatically severe Great Escarpment tend to flower during spring when temperatures are on the increase. Two such species are A. broomii Schönland (1907: 137) and A. grandidentata Salm-Dyck (1822: 3 [species no. 2]).


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