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BOTHALIA – African Biodiversity & Conservation
ISSN: (Online) 2311-9284, (Print) 0006-8241
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| Original researchPage 1 of 34
Authors
1Prof. Ben Strohbach
Aliations
1Biodiversity Research Centre,
Namibia University of Science
and Technology, Private Bag
13388, Windhoek, Namibia.
Corresponding Author
Prof. Ben Strohbach, e-mail:
bstrohbach@nust.na
Dates
Submitted: 1 July 2020
Accepted: 15 April 2021
Published: 15 July 2021
How to cite this article:
Strohbach, B., 2021, ‘Vegetation
survey of the Khomas Hochland
in central-western Namibia:
syntaxonomical descriptions’,
Bothalia 51(2), a4. http://dx.doi.
org/10.38201/btha.abc.v51.i2.4
Copyright: © 2021. The Authors.
Licensee: SANBI. This work is
licensed under the Creative
Commons Attribution 4.0
International License.
Background: The Great Escarpment of southern Africa takes the form of an ex-
tended 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 Kho-
mas Hochland is formed on the southern part of the Damara Orogen and dom-
inated 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 vegeta-
tion 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 um-
brella 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 hab-
itats 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 classi-
fication. The fifth order, the Senegalio hereroensis–Tarchonanthoetalia camphor-
athi, represents high mountains of the central Khomas Hochland, which link bio-
geographically to the grassland biome in South Africa.
Keywords: Damara Orogen; Great Escarpment; highland savanna; modified
TWINSPAN; Namib; phytosociology.
Introduction
The Great Escarpment is a ± 5000 km long geomorphological feature along the
rim of the southern African subcontinent. It is regarded as a zone of high bio-
logical diversity, containing numerous Centres of Endemism (Clark et al. 2011).
Whereas most of the Great Escarpment forms a narrow divide between the
coastal lowlands and the inland plateaux, in central Namibia the Damara Oro-
gen created a mountainous landscape nearly 200 km wide from west to east.
This mountainous landscape is commonly referred to as the Khomas Hochland
(or Khomas highlands) (Schneider 2004; Swart & Marais 2009; Goudie & Viles
Vegetation survey of the Khomas
Hochland in central-western Namibia:
syntaxonomical descriptions
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Page 2 of 34
2014). Giess (1998) broadly describes the vegetation
as ‘highland savanna’, without providing any details on
composition or diversity.
Although the Khomas Hochland has been identified as
an area of high botanical diversity (Hofmeyr 2004; Cra-
ven & Vorster 2006), only a few localised descriptions
of the vegetation of this landscape exists. Of note here
are a study by Volk and Leippert (1971) on a few farms
southeast of Windhoek, using data from the 1950s and
1960s; an unpublished study by Kellner (1986) focusing
on the Daan Viljoen Game Reserve west of Windhoek
as well as portions of two farms southwest and east of
Windhoek; a preliminary description of the vegetation
of the Auas Mountain Range south of Windhoek (Burke
& Wittneben 2007); as well as an account of the veg-
etation of the Auas-Oanob Conservancy southwest of
Windhoek (Strohbach 2017). None of these studies
provide a comprehensive overview of the entire land-
scape. In contrast, a fairly comprehensive description of
the adjacent central Namib desert is available (Jürgens
et al. 2013).
The Vegetation Survey of Namibia project has been ini-
tiated to fill this, and similar data gaps, at a national
level (Burke & Strohbach 2000; Strohbach 2001). The
project is aimed at providing data about the resource
‘natural vegetation’ to allow for sustainable planning
and management of this renewable resource (Strohbach
2018). Due to the sheer size of the country, however,
a strong emphasis is placed on utilising existing reliable
data sources in addition to collecting, over a number of
seasons, additional, gap-filling data. At the same time,
due to the lack of necessary data density for a detailed
study, the result will be at a regional overview level
(often referred to as ‘reconnaissance level’) (Küchler &
Zonneveld 1988; Strohbach 2001). This paper aims to
contribute a first formal classification and description at
this level of the vegetation found in the Khomas Hoch-
land in central-western Namibia.
Methods
Study area
The study area is a block of roughly 31 000 km2 in cen-
tral western Namibia, between the coastal Namib desert
lowlands and the inland plateaux (Figure 1). It stretches
from the border of the Namib-Naukluft Park in the west
to about 17° 30’E, and from the B6 trunk road between
Okahandja and Karibib in the north to about the Gaub
Valley in the south. Administratively, it covers the west-
ern half of the Khomas Region, but also reaches into the
Erongo and Otjozondjupa regions of Namibia.
The Khomas Hochland had its origin some 900 Ma ago
as a sea between two tectonic plates, the Kalahari- and
Congo cratons. Sediments deposited in this sea solid-
ified and were metamorphised during the formation
of the Gondwana supercontinent ± 650 to 450 Ma
ago. At that stage, uplift also happened, resulting in the
Damara Orogen (Schneider 2004; Swart & Marais
Figure 1. The study area in western
central Namibia. Mean Annual
Rainfall is indicated as blue isohy-
ets. Data source: NARIS (2001).
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Page 3 of 34
2009). The main body of the Khomas Hochland consists
of mica schists of the Kuiseb and schists and mixtites of
the Chuos Formation (Figure 2A). The mica schists of
the Kuiseb Formation are dissected by a narrow band
of ortho-amphibolites of the Matchless Member. The
southern rim is formed by hardened quartzites of the
Auas Formation, before merging with older rocks (gran-
ites and metamorphites of the Rehoboth Sequence) of
the Kalahari Craton. To the north of the Kuiseb forma-
tion, intrusive granites resulted also in the formation of
several marble ridges (Figure 2A) (Geological Survey
1980; South African Committee for Stratigraphy 1980;
Schneider 2004).
The escarpment of the Khomas Hochland raises from
the Namib desert plains at about 900 m above sea lev-
el (asl) to well over 1 400 m asl. The central Khomas
Hochland forms a deeply dissected, steep mountainous
highland, raising to over 2 000 m asl in places (Figure
2B) (Swart & Marais 2009). This is only topped by the
mountain ranges Auas, Lichtenstein, Hakos and Gams-
berg, which reach altitudes of over 2 400 m asl (Schalk
1983; Swart & Marais 2009). The study area is drained
through a dense system of ephemeral rivers, forming
tributaries to the Swakop and Kuiseb rivers to the west,
Oanaob and Skaap rivers to the southeast, and White
Nossob as well as Olifants rivers to the east (Figure 2b)
(Strohbach 2008).
The climate can be described as a hot desert in the
western half to a hot steppe in the eastern half, fol-
lowing Köppen (1936). The mean annual precipita-
tion (MAP) ranges from ± 50 mm in the west to about
350 mm in the east (Figures 1 and 3), with a high de-
gree of variation between seasons. Along the western
edge of the study area, the coefficient of variation (CV)
Figure 2. A, Simplified geological
map of the study area, indicating
the major lithological substrates;
B, Topography of the study area,
indicating several landmarks and
major rivers draining the Khomas
Hochland. Data sources: Geolog-
ical map adapted from Namibia
Geological Map (Geological Sur-
vey 1980); topography derived
from SRTM image (Jarvis et al.
2008).
A
B
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of MAP is as high as 90%, in the east around Windhoek
the CV of MAP is about 40% (Mendelsohn et al. 2002).
The orographic effect of the escarpment and high
mountains in the study area are not known. The desert
margins below the escarpment become relatively hot,
with maximum temperatures measured well over 40°C.
Frost is also rare or absent here. In contrast, the cen-
tral highlands are cooler, with maximum temperatures
around 36°C. Frost regularly occurs in the highlands in
the winter months between May and August, at places
as late as October (Figure 3).
Data sources
A data set of 1 151 relevés with 914 species was se-
lected from the phytosociological database of Namibia
(GVID ID AF-NA-001) (Strohbach & Kangombe 2012).
Details of the selected data subsets are listed in Table 1.
The quality of the rainy season, which has an influence
on the growth of the vegetation, was derived according
to the criteria of Botha (1998). Normal years had an
annual precipitation of between the 40th and 70th
percentile of long-term precipitation records, whilst ex-
treme years had below the 10th (extreme dry) or above
the 90th percentile (extreme wet) annual precipitation.
Data collected by Kellner (1986) was captured from ta-
bles in his thesis as the original relevé data (field sheets)
were no longer available. These relevés were also col-
lected from 25 × 25 m (i.e. 625 m2) plots. No accurate
position data, nor habitat data, are available for these
relevés. Data collected by Burke, Wittneben and Mann-
heimer (Auas Mountains and Windhoek Townlands)
were in the form of species lists on specific sites rather
than regular survey plots. Position data are available in
most cases, but the habitat data are incomplete. These
data were however included, as the sites were limited
to specific habitats and limited in sizes (no longer than
100 m, no wider than 10 m), i.e. comparable to regular
survey sites used for the Vegetation Survey of Namibia
project. Especially the data by Burke and Wittneben
A B C
D E F
Figure 3. Climate diagrams after Walter et al. (1975) of available automatic weather stations within the study area: Ganab, Rooisand,
Claratal, Narais, Windhoek (NBRI) and Okamboro. Data sources: SASSCAL (2020) and BIOTA AFRICA (2009).
Page 4 of 34
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(2007) covered extreme, inaccessible habitats, making
the data invaluable for the completeness of this study.
All other surveys followed the guidelines of the Vegeta-
tion Survey of Namibia project, i.e. were surveyed on
a 20 × 50 m (1 000 m2) plot, whilst plot layout was re-
stricted to a specific habitat. In cases where the nature
of the habitat did not allow a 20 m × 50 m sized plot
(e.g. riverine habitats, rock outcrops), the plot shape
was adapted to fit the habitat, without reducing the
size, nor moving into a different habitat. The size of
20 × 50 m was chosen as suitable for an arid savanna
and conforms to size criteria proposed by Brown et al.
(2013). For these relevés, the position as determined by
GPS, as well as habitat descriptors related to landscape,
topography, lithology and stone cover have been noted.
Unknown species were collected for identification in
the National Herbarium of Namibia (WIND). Species’
nomenclature follows Klaassen and Kwembeya (2013),
with the exception of the genus Acacia s.l., for which
Kyalangalilwa et al. (2013) was followed.
Classication procedures
An initial classification was done using modified TWIN-
SPAN (Roleček et al. 2009), with average Sørensen as
distance measure, and utilising pseudospecies cut levels
at 0 and 5% cover to differentiate between low-cover
desert margin vegetation and inland vegetation at high-
er cover values. This classification was based on syn-
usial data (i.e. trees, shrubs, dwarf shrubs and grasses
Table 1. Overview of data used for this study. All data form part of GVID ID AF-NA-001 (Strohbach & Kangombe 2012)
Relevés Dataset name Number Year Season
quality
Surveyor Area of interest Reference
(if any)
937–1165 BS_Auas-Oanob 229 2000
&
2002
Extreme
wet
Normal
B. Strohbach Auas-Oanob
Conservancy
(Strohbach
2017)
1833–2180 Khomas_2004 204 2004 Normal B. Strohbach Khomas Hochland
(Kuiseb valley)
2212–2258 Khomas_2005 124 2005 Dry B. Strohbach Khomas Hochland
(Kuiseb valley)
2797–2977 Kellner_1985 181 1985 Normal K. Kellner Daan Viljoen,
Claratal, Bergvlug
(Kellner 1986)
5798–5854
and 5900–
5914 and
5980–5987
Zuna_2005 80 of 204 2005 Dry Z. September Biota transect Aris
to Witvlei (limited to
17°30’ East)
7114–7140 BS-SK_
Khomas_2007
27 2007 Normal B. Strohbach
& S. Kruger
Windhoek area
9438–9564 BS_
Khomas_2009
127 2009 Wet B. Strohbach Northern and
western Khomas
9565–9598 Auas_
W+B_2004
34 2004 Normal A. Burke &
M. Wittneben
Auas Mountain
Range
(Burke &
Wittneben
2007;
Strohbach
2017)
10192–
10221
CM_Windhoek-
townlands
30 2009 Wet C.
Mannheimer
Windhoek
Townlands
10612–
10632
BS_Narais_2011 21 2011 Wet B. Strohbach Narais observatory BIOTA
observatory
(Jürgens et al.
2010)
11475–
11540
BS_
Midgard-2014
66 2014 Extreme
wet
B. Strohbach Midgard Country
Estate (south)
70001–
70028
Ovitoto_2001 28 2001 Normal T. Sheuyange Ovitoto Observatory BIOTA
observatory
(Jürgens et al.
2010)
Page 5 of 34
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only) (Gillet & Julve 2018), and resulted in three clus-
ters. These clusters were interpreted as representing the
Pre-Namib and Escarpment zone, the central Khomas
Hochland as well as a third group comprising riverine
habitats and lowlands surrounding the Khomas Hoch-
land. This classification result was used to split the data
set into three subsets for further analysis.
The three clusters were further classified using the mod-
ified TWINSPAN classification algorithm, always using
average Sørensen as distance measure, and utilising
pseudospecies. For the Pre-Namib/Escarpment zone
cluster, these were kept at 0 and 5%; for the other clus-
ters cut levels were set at 0 and 10%. This difference
in pseudospecies cut levels was necessary because the
Pre-Namib has an inherent lower vegetation cover than
the inland vegetation. In the case of Cluster 3 (riverine
and lowland habitats), the data set was again split into
two subsets after an initial classification using synusial
data. The level of splitting was determined using peaks
in crispness values (Botta-Dukát et al. 2005).
The classification of the clusters using synusial data was
transferred to the full data set. Analysis of the resulting
clusters revealed partial mixing of relevés between as-
sociations, or in several cases, known units to be includ-
ed in other associations. This prompted a refinement
of the classification results using Cocktail procedures
(Bruelheide & Flintrop 1994; Bruelheide 1997), based
on existing descriptions (e.g. Kellner 1986; Strohbach
2017), or on field observations. A detailed account of
these Cocktail refinements is presented in the Results
section of this paper.
Once an ecologically interpretable result was achieved,
phytosociological tables were compiled and the synop-
sis for various associations extracted. Diagnostic species
were determined using the phi coefficient of association
(Chytrý et al. 2002). For this calculation the numbers of
relevés were standardised following Tichý and Chytrý
(2006). Species with phi ≥ 40 were considered as diag-
nostic and with phi ≥ 60 as highly diagnostic; however,
species with a non-significant fidelity at α = 0.05 using
Fisher’s exact test were omitted. Species occurring with
at least a 60% frequency were regarded as constant and
with at least an 80% frequency as highly constant.
Further descriptors of
the associations
The average structure for each grouping (i.e. aver-
age tree, shrub, dwarf shrub, perennial grass, annual
grass and herb cover) was calculated using the avail-
able growth form data. Descriptions follow Edwards
(1983). For the species density (number of species per
1 000 m2), the relevé data from Kellner (1986) were
excluded, as these were sampled on 625 m2 plots (25
× 25 m), not 1 000 m2 plots as for all other relevés. In
addition, an estimate of potential species richness for
the association has been calculated with a first order
Jackknife as proposed by Heltshe and Forrester (1983)
as well as Palmer (1990).
Higher syntaxonomy
Due to the extensive refining of clusters with Cocktail,
partially resulting in splitting of clusters or the definition
of new clusters, the initial classification dendrograms
could not be used as an indication of higher-order syn-
taxonomy as is customary (e.g. Luther-Mosebach et al.
2012). Instead, synoptic tables of the associations were
prepared using percentage frequency for all four classi-
fications. The synopsis of each association was taken as
a pseudo-relevé, and these were combined into a sin-
gle data set for classification with modified TWINSPAN
(Roleček et al. 2009). No pseudospecies were used for
this classification. This approach follows broadly the ap-
proached used by Winterbach et al. (2000).
Results
First classication results
and Cocktail renements
The first classification resulted in three major vegetation
zones, namely the Pre-Namib and Escarpment zone,
the Khomas Hochland proper and the riverine habi-
tats and lowlands vegetation surrounding the Khomas
Hochland. The latter was further subdivided into two
subsets for further classification. Cocktail refinements
were necessary on all four clusters. Details of these re-
finements are provided in Table 2.
Pre-Namib and Escarpment zone
The vegetation of the Pre-Namib (Vornamib sensu Giess
(1962, 1998) and Escarpment zone is dominated by
the plant families Poaceae, Fabaceae, Bignoniaceae
and Burseraceae, in descending order of importance.
The classification resulted in seven associations, which
are formally described according to the International
Code of Phytosociological Nomenclature (Weber et
al. 2000). The synoptic table for these is presented in
Appendix 1, and the phytosociological table in Appen-
dix 2, available online only (DOI: http://dx.doi.org/
10.38201/btha.abc.v51.i2.s4a, DOI: http://dx.doi.org/
10.38201/btha.abc.v51.i2.s4b).
Within the synopsis, basic statistics on the association
(or other syntaxa) are given, as derived from the anal-
ysis of clusters in Juice. Highly diagnostic species (with
phi coefficient >60) and highly constant species (oc-
curring in more than 80% of relevés) are indicated in
bold. All structural descriptions follow Edwards (1983).
Landscape descriptors follow conventions of the Digital
Page 6 of 34
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Unit changed Selection based on following criteria Relevés involved Based on
Cluster 1: Pre-Namib and Escarpment zone:
This data cluster consisted of 279 relevés and 329 species. The synusial data had only 121 species. Classification of this
subset resulted in five clusters, which were refined as follows:
Karpfenkliffs (Association
1.1)
Adenolobus pechuelii, Enneapogon
desvauxii, Fagonia isotricha
8 relevés from Cluster 1 Field observations
Rostock sand drift plains
(Association 1.3)
Crotalaria podocarpa, Sesuvium
sesuvioides, Crinum macowani,
Kohautia caespitosa, Stipagrostis
obtusa, Grielum sinuatum
7 relevés from Cluster 1 Field observations
Gravel plains of Pre-
Namib (Association 1.2)
Remainder of Cluster 1
Cluster 2: Khomas Hochland proper:
This data cluster consisted of 350 relevés with 588 species. The synusial data set had only 198 species. Classification of this
subset resulted in five clusters. Refinements were done as follows:
Steep cliff faces
(Association 2.2)
Ficus ilicina, Pennisetum foermeranum,
Steganotaenia araliacea. A minimum of
two of these species had to be present
5 relevés from Cluster 4 (rock
outcrops)
Kellner 1986
Cluster 3 senso lato Osyris lanceolata, Hypoestes forskaolii,
Danthoniopsis ramosa
13 relevés from Cluster 5 Strohbach 2017
High altitude mountain
veld of the south-facing
slopes (Association 2.3)
Jamesbrittenia pallida, Selago
alopecuroides, Frankenia pomonensis,
Eriocephalus dinteri
Split from Cluster 3 (8 relevés) Strohbach 2017
High altitude mountain
veld of the north-facing
slopes (Association 2.4)
Selago angustibractea, Lopholaena
cneorifolia, Cheilanthes multifida,
Babiana hypogea, Eriocephalus
scariosus and Adromischus species
Split from Cluster 3 (8 relevés) Strohbach 2017
Mid-altitude mountain
veld (Association 2.5)
Remainder of Cluster 3
Oamites mountain veld
(Association 2.7)
Ornithoglossum calcicola and
Melhania damarana
Split from Cluster 5 (9 relevés) Strohbach 2017
Khomas Hochland
mountain veld
(Association 2.8)
Remainder of Cluster 5
Cluster 3: Riverine habitats:
This data cluster consisted of 59 relevés and 304 species. The synusial data contained only 114 species. Classification of this
subset resulted in eight clusters. Due to high intrinsic variation however, not all associations were ecological interpretable,
and extensive refinement, including partial recombination of relevés into associations was necessary.
Dry riverbeds (Association
3.2)
Recombined clusters 2, 3 and 4
as one
Cluster 5 senso lato High abundance of Stipagrostis
namaquensis
Split into two
Riverine sand banks
(Association 3.3)
High abundance of Stipagrostis
namaquensis
Cluster 5A (3 relevés), as well as
1 relevé from Cluster 7 and 1
relevé from Cluster 8
Strohbach 2017
Inland riparian woodlands
(Association 3.5)
High abundance of Vachellia karroo Clusters 5B and 6, as well
as several relevés from the
surrounding lowlands (Cluster
4, mostly relevés sampled by
Kellner (1986)) found to fit into
this group. These were manually
moved here.
Strohbach 2017;
Kellner 1986
Table 2. Refinements necessary to the classification results for improved ecological interpretability
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Unit changed Selection based on following criteria Relevés involved Based on
Cluster 3: Riverine habitats (continued)
Omirimbi vegetation
(Association 3.4)
Manual selection according to habitat
description, verified with Cocktail
based on Tragus berteronianus,
Schmidtia pappophoroides,
Themeda triandra, Talinum caffrum,
Platycarphella carlinoides, Monsonia
angustifolia, Microchloa caffra, Chloris
virgata
Remainder of clusters 5 and 6,
but weakly defined
Volk & Leippert
1971; Strohbach
2017
Riparian woodlands
of the westerly rivers
(Association 3.6)
Tamarix usneoides, Salvadora persica,
Euclea pseudebenus, Stipagrostis
hochstetteriana and Faidherbia albida
Cluster 7 (remainder) and 1
relevé from Cluster 6
Field observations
Big inland rivers
(Association 3.8) and
Omeya plains vegetation
(Association 4.7)
Geographical location and habitat Several relevés grouped into
Cluster 8 (big inland rivers)
were found to belong to the
Omeya plains according to their
location. These were manually
moved to the data subset of
Cluster 4, Association 4.7
Cluster 4: Lowlands surrounding the Khomas Hochland:
This data cluster consisted of 462 relevés and 688 species. The synusial data set contained only 227 species. Classification
of this data set resulted in ten clusters. On closer inspection, these were found to be fairly mixed due to the synusial data
reduction, requiring extensive refinement through Cocktail procedures as follows:
Oanob Plateau
(Association 4.2)
Panicum lanipes, Plinthus sericeus,
Pteronia eenii, Pentzia incana and
Blepharis integrifolia
Clusters 2 and 3 Strohbach 2017
Cluster 3 senso lato
(weakly defined)
Remainder of clusters 2 and 3
Gölschau plains
(Association 4.3)
Aptosimum spinescens, Eriocephalus
ericoides, Geigeria pectidea and
Galenia africana
From Cluster 3 senso lato Field observations
Southern Khomas
(Association 4.4)
Aizoon schellenbergii, Panicum
arbusculum, Hibiscus discophorus,
Kohautia cynanchica and Aptosimum
albomarginatum
From Cluster 3 senso lato Strohbach 2017
Degraded/bush
encroached vegetation
of the Khomas Hochland
(Sub-association 4.8.1)
Remainder of Cluster 3 senso
lato, combined with Cluster 9
Strohbach 2017
Khomas Hochland
lowlands (Association 4.6)
Senegalia erubescens, Combretum
apiculatum, Grewia flavescens and
Dichrostachys cinerea (minimum of
two species, with high abundance of
Senegalia erubescens)
Cluster 5, with extra relevés
from Cluster 10
Field observations
Khomas Hochland
lowlands (Sub-association
4.8.1)
Vachellia reficiens at high abundance Remainder of Cluster 10,
excluding clusters 8 and 9
Field observations
Khomas Hochland
lowlands (Association 4.8)
The recombined Clusters
7 and 10, as well as the
original Clusters 8 and 9 were
recognised as sub-associations
of association 4.8.
Table 2. Refinements necessary to the classification results for improved ecological interpretability (continued)
Page 8 of 34
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Soil and Terrain Database (SOTER) of FAO (FAO 1993).
Specifically, the following slope classes apply:
•Flat: 0–1° / 0–2%
•Gently undulating: 1–3° / 2–5%
•Undulating: 3–6° / 5–10%
•Rolling: 6–9° / 10–15%
•Moderately steep: 9–17° / 15–30%
•Steep: 17–30° / 30–60%
•Very steep: >30° / >60%
This format is also followed for all further descriptions
in this paper.
1.1 Enneapogono desvauxii–
Adenoloboetum pechuelii ass. nov.
Synopsis:
Number of relevés: 8
Type relevé: 2065 (holotype), sampled on 15 March
2005 at 23°28’01”S, 16°05’22”E
Number of species observed: 27
Estimated number of species: 46
Average species density per 1 000 m2: 14
Diagnostic species: Adenolobus pechuelii, Fagonia iso-
tricha var. isotricha, Enneapogon desvauxii, Indigo-
fera auricoma
Constant species: Euphorbia glanduligera, Eragrostis
nindensis, Stipagrostis hirtigluma, Tribulus zeyheri
These low desert herblands (Figures 4A and 5B) are
dominated by Eragrostis nindensis and Enneapogon
desvauxii. This association occurs on old eroded fluvial
deposits commonly referred to as ‘Karpfenkliff Con-
glomerate’ (Ward 1987) along the upper reaches of
the Kuiseb and Gaub canyons, with altitudinal ranges
between 800 and 1 100 m asl. The substrate consists
of carbonate-cemented conglomerates, which are be-
tween 40 and 60 m deep. The erosion of these con-
glomerates results in a steeply dissected hill landscape.
Low rainfall (between 100 and 150 mm Mean Annual
Precipitation – MAP), high runoff and a compact sub-
strate allowing little infiltration result in this depauper-
ated form (diversity- and cover-wise) of the Enneapogo-
no desvauxii–Eragrostietum nindensis. Because of its
unique habitat, it is recognised as an association.
1.2 Enneapogono desvauxii–
Eragrostietum nindensis ass. nov.
Synopsis:
Number of relevés: 82
Type relevé: 9439 (holotype), sampled on 10 March
2009 at 22°54’06”S, 16°37’36”E
Number of species observed: 64
Estimated number of species: 111
Average species density per 1 000 m2: 16
Diagnostic species: Enneapogon desvauxii
Constant species: Eragrostis nindensis, Tribulus zey-
heri, Euphorbia glanduligera, Stipagrostis ciliata, Sti-
pagrostis hirtigluma
These low desert grasslands (sometimes rather des-
ert shrublands) are dominated by Eragrostis nindensis
and various other grass, herb and dwarfshrub species
(Figures 4B and 5B). This association occurs on the ex-
pansive calcrete gravel plains of the Pre-Namib and
has been described by Jürgens et al. (2013) as ‘eastern
calcrete plains grasslands’. The altitude ranges between
780 and 1 300 m asl, and the landscape is generally
flat. MAP ranges between 50 and 150 mm, but because
of the reduced run-off and looser substrate, this associ-
ation is far more species rich compared to the Enneap-
ogono desvauxii–Adenoloboetum pechuelii (depending
on the quality of the rainfall season).
1.3 Crotalario podocarpae–
Stipagrostioetum obtusae ass. nov.
Synopsis:
Number of relevés: 7
Type relevé: 1997 (holotype), sampled on 19 Febru-
ary 2004 at 23°20’49”S, 15°56’58”E
Number of species observed: 23
Estimated number of species: 34
Average species density per 1 000 m2: 11
Diagnostic species: Crotalaria podocarpa, Stipagros-
tis obtusa, Sesuvium sesuvioides, Grielum sinua-
tum, Crinum macowanii, Kohautia caespitosa subsp.
brachyloba, Limeum myosotis, Stipagrostis ciliata
These short open grasslands are dominated by Stipa-
grostis ciliata and Stipagrostis obtusa (Figures 4C and
5C), occurring on sand drift plains in the Pre-Namib.
Striking examples are found along the western end of
the C26 main road before joining the C14. The topog-
raphy is an undulating sand drift plain, ranging between
1 050 and 1 100 m asl. This area receives between 50
and 100 mm MAP.
1.4 Tribulocarpo dimorphantho–
Vachellietum eriolobae ass. nov.
Synopsis:
Number of relevés: 4
Type relevé: 2013 (holotype), sampled on 20 Febru-
ary 2004 at 23°15’57”S, 16°07’28”E
Number of species observed: 22
Estimated number of species: 26
Average species density per 1 000 m2: 15
Diagnostic species: Xenostegia tridentata subsp. angus-
tifolia, Requienia sphaerosperma, Harpagophytum
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procumbens, Hermannia guerkeana, Oxygonum
alatum, Tribulocarpus dimorphanthus, Brachiaria
glomerata, Ipomoea magnusiana, Vachellia eriolo-
ba, Gisekia africana, Centropodia glauca, Stipagrostis
hochstetteriana, Dicoma capensis, Stipagrostis cilia-
ta, Heliotropium nelsonii
Constant species: Stipagrostis uniplumis var. uniplumis
This short desert woodland is dominated by Stipagrostis
uniplumis var. uniplumis and Stipagrostis ciliata with a
scattered cover of Vachellia erioloba trees (Figures 4D
and 5D). It is situated further inland from the Crota-
lario podocarpae–Stipagrostioetum obtusae in the val-
leys below the escarpment at an altitudinal range of
between 1 200 and 1 250 m. The substrate is aeolian
Kalahari sands, thus supporting typical Kalahari ele-
ments like Vachellia erioloba, Brachiaria glomerata, Re-
quienia sphaerosperma and Harpagophytum procum-
bens. MAP ranges between 100 and 150 mm.
1.5 Geigerio acaulis–Commiphoroetum
glaucescentis ass. nov.
Synopsis:
Number of relevés: 59
Type relevé: 9467 (holotype), sampled on 12 March
2009 at 22°21’16”S, 15°49’55”E
Number of species observed: 165
A B
C D
E F
G
Figure 4. Box-and-Whisker plots of the typical structure of the
associations of the Pre-Namib and Escarpment zone, based
on the relevé data. A, Enneapogono desvauxii–Adenoloboe-
tum pechuelii; B, Enneapogono desvauxii–Eragrostietum nin-
densis; C, Crotalario podocarpae–Stipagrostioetum obtusae;
D, Tribulocarpo dimorphantho–Vachellietum eriolobae; E,
Geigerio acaulis–Commiphoroetum glaucescentis; F, Myro-
thamno flabellifolii–Commiphoroetum dinteri; G, Eragrostio
nindensis–Vachellietum reficientis.
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A
Figure 5. Typical views of the associations of the Pre-Namib and
Escarpment zone. A, Enneapogono desvauxii–Adenoloboetum
pechuelii, relevé 2065; B, Enneapogono desvauxii–Eragrosti-
etum nindensis, relevé 9439; C, Crotalario podocarpae–Sti-
pagrostioetum obtusae, relevé 1997; D, Tribulocarpo dimor-
phantho–Vachellietum eriolobae, relevé 2013; E, Geigerio
acaulis–Commiphoroetum glaucescentis, relevé 9467; F, My-
rothamno flabellifolii–Commiphoroetum dinteri, relevé 1969;
G, Eragrostio nindensis–Vachellietum reficientis, relevé 1970.
Photos by the author.
C
E
G
B
D
F
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Estimated number of species: 214
Average species density per 1 000 m2: 33
Diagnostic species: Schmidtia kalahariensis, Aristida
adscensionis, Melinis repens subsp. grandiflora,
Lycium bosciifolium, Aristida effusa, Eragrostis poro-
sa, Enneapogon cenchroides, Geigeria acaulis, Albi-
zia anthelmintica, Aptosimum arenarium, Merremia
bipinnatipartita, Senegalia erubescens, Grewia tenax,
Kyphocarpa angustifolia
Constant species: Stipagrostis uniplumis var. uniplu-
mis, Eragrostis nindensis, Stipagrostis hochstetteri-
ana, Boscia foetida, Vachellia reficiens
These semi-open high shrublands are strikingly charac-
terised by scattered trees of Commiphora glaucescens
(Figures 4E and 5E). They occur on the slightly undu-
lating plains surrounding Otjimbingwe, on Donkerhuk
granites, north of the central Khomas Hochland com-
plex. Typical for these granite-derived soils in arid envi-
ronments is a very high (80% or more) cover by granitic
gravel. The altitude ranges between 900 and 1 300 m
asl, whilst MAP ranges between 150 and 250 mm.
1.6 Myrothamno flabellifolii–
Commiphoroetum dinteri ass.nov.
Synopsis:
Number of relevés: 42
Type relevé: 1968 (holotype), sampled on 18 Febru-
ary 2004 at 23°01’49”S, 16°07’24”E
Number of species observed: 123
Estimated number of species: 173
Average species density per 1 000 m2: 29
Diagnostic species: Commiphora dinteri, Forsska-
olea viridis, Sterculia africana, Myrothamnus flabel-
lifolius, Cheilanthes hirta, Talinum caffrum, Com-
miphora glaucescens, Elephantorrhiza suffruticosa,
Calostephane marlothiana, Monechma spartioides,
Blepharis obmitrata, Setaria appendiculata, Amphias-
ma divaricatum, Triraphis ramosissima, Dyerophytum
africanum, Barleria lancifolia
Constant species: Stipagrostis uniplumis var. uniplu-
mis, Eragrostis nindensis, Tribulus zeyheri, Tephro-
sia dregeana var. dregeana
These low open bushlands are characterised by a vari-
ety of stem succulents typical of the escarpment zone
(Figures 4F and 5F). They occur on the inselberg ranges
along the Pre-Namib fringes as well as the lower escarp-
ment zone, at an altitudinal range between 1 050 and
1 500 m asl. The topography consists of steep moun-
tain slopes generally with a gradient of well above 30%,
as well as with considerable stone cover (up to 80%),
mostly small, medium and large stones. MAP ranges
between 100 and 200 mm.
1.7 Eragrostio nindensis–Vachellietum
recientis ass. nov.
Synopsis:
Number of relevés: 77
Type relevé: 1970 (holotype), sampled on 18 Febru-
ary 2004 at 23°02’24”S, 16°08’18”E
Number of species observed: 97
Estimated number of species: 153
Average species density per 1000 m2: 23
Diagnostic species: none
Constant species: Eragrostis nindensis, Stipagrostis
uniplumis var. uniplumis, Euphorbia glanduligera,
Tribulus zeyheri, Entoplocamia aristulata, Catophrac-
tes alexandri, Monsonia senegalensis, Leucosphaera
bainesii
These tall open shrublands are dominated by Stipa-
grostis uniplumis var. uniplumis, Vachellia reficiens,
Catophractes alexandri, Eragrostis nindensis, Enneap-
ogon desvauxii, Aristida adscensionis and Senegalia eru-
bescens (Figures 4G and 5G). They occur on rolling to
moderately steep (10–30%) plains and footslopes of the
escarpment, often occurring far inland in valleys of the
escarpment. Stone cover is not as high, roughly 40%,
again mostly small, medium and large stones. The alti-
tude ranges between 950 and 1 400 m asl, whilst MAP
ranges between 100 and 250 mm.
Khomas Hochland proper
The vegetation of the Khomas Hochland is dominat-
ed by the plant families Poaceae, Asteraceae, Faba-
ceae and Scrophulariaceae. The classification resulted
in eight associations, which are formally described ac-
cording to the International Code of Phytosociological
Nomenclature (Weber et al. 2000) below (with one ex-
ception). The synoptic table for these is presented in
online Appendix 1, and the phytosociological table in
online Appendix 2.
2.1 Digitario erianthae–Euryopietum
walterorum ass. nov.
Synopsis:
Number of relevés: 6
Type relevé: 1838 (holotype), sampled on 9 Febru-
ary 2004 at 23°20’19”S, 16°13’50”E
Number of species observed: 44
Estimated number of species: 70
Average species density per 1 000 m2: 15
Diagnostic species: Panicum lanipes, Euryops walter-
orum, Eriospermum bakerianum subsp. bakeria-
num, Hypertelis salsoloides, Boophone disticha
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Constant species: Eragrostis nindensis, Digitaria erian-
tha
This moderately closed, short shrubland is dominated by
the name-giving Euryops walterorum, Eriocephalus din-
teri and Digitaria eriantha (Figures 6A and 7A). The occur-
rence of Euryops walterorum is restricted to the Gams-
berg Plateau (i.e. a limited-range endemic) (Nordenstam
1966; Loots 2005), which is 210 ha in size. The plateau
consists of a fine-grained quartzite layer ± 30 m thick, at
an altitude 2 347 m asl (Wittig 1976; Schalk 1983). The
topography is near flat but displays a conspicuous cover
by large stones of roughly 40%. The plateau receives an
estimated 150 mm MAP, based on general rainfall maps
(Mendelsohn et al. 2002). This, however, does not take
any possible orographic effects into account.
2.2 Pennisetum foermerianum–
Ficus ilicina association
Synopsis:
Number of relevés: 6
Number of species observed: 97
Estimated number of species: 161
Average species density per 1 000 m2: 23
Diagnostic species: Ficus ilicina, Pennisetum foermer-
ianum, Steganotaenia araliacea var. araliacea, Bul-
bostylis hispidula, Hermannia tigrensis, Datura inoxia,
Cyphostemma hereroense, Calostephane divaricata,
Eragrostis porosa, Sporobolus fimbriatus, Boscia al-
bitrunca, Cheilanthes marlothii, Ozoroa crassinervia,
Pupalia lappacea
Constant species: Tarchonanthus camphoratus, Sear-
sia marlothii, Combretum apiculatum subsp.
apiculatum, Triraphis ramosissima, Melinis repens
subsp. grandiflora, Enneapogon cenchroides, Senega-
lia hereroensis
This association is difficult to assign to a structural type, as
the vertical dimension is dominated by the habitat, being
near-vertical rock faces (Figures 6B and 7B). Most woody
species have a shrub-like habit, making it essentially a
short, semi-open shrubland. However, e.g. Ozoroa
crassinervia grows to a distinct tree. This association oc-
curs on steep rock faces throughout the central Khomas
Hochland. Kellner (1986) includes this in his Pennisetum
foermerianum–Dombeya rotundifolia association, even
though it is, based on its habitat and species composition,
distinctly different. Due to the low sampling density and
inherent variability it is not described formally.
2.3 Eriocephalo dinteri–Danthoniopietum
ramosae ass. nov.
Synopsis:
Number of relevés: 8
Type relevé: 9595 (holotype)
Number of species observed: 69
Estimated number of species: 93
Average species density per 1 000 m2: 27
Diagnostic species: Jamesbrittenia pallida, Selago al-
opecuroides, Eriocephalus dinteri, Frankenia po-
monensis, Senecio inaequidens, Cheilanthes hirta,
Leucas glabrata, Hypoestes forskaolii, Namacodon
schinzianum, Danthoniopsis ramosa, Lepidium afri-
canum, Kalanchoe species
Constant species: Digitaria eriantha, Oxalis purpuras-
cens, Tarchonanthus camphoratus, Eragrostis sco-
pelophila, Eragrostis nindensis
These short, closed grasslands have a dense cover
of perennial grasses like Digitaria eriantha, Eragrostis
scopelophila, Danthoniopsis ramosa and Andropogon
chinensis (Figure 6C). Scattered Tarchonanthus cam-
phoratus and Senegalia hereroensis shrubs also occur.
This association occurs on the very steep (> 60%)
southern slopes of the Auas Mountain range, at alti-
tudes from 2 150 m asl upwards (Burke & Wittneben
2007; Strohbach 2017). MAP is about 350 mm (Men-
delsohn et al. 2002), again not taking any orographic
effects into account.
2.4 Danthoniopio ramosae–
Oleoetum africanae ass. nov.
Synopsis:
Number of relevés: 8
Type relevé: 9592 (holotype), sampled on 13 March
2004 at 22°37’05”S, 17°13’14”E
Number of species observed: 122
Estimated number of species: 151
Average species density per 1 000 m2: 63
Diagnostic species: Selago angustibractea, Lopho-
laena cneorifolia, Cheilanthes multifida, Caloste-
phane marlothiana, Adromischus species, Mon-
sonia burkeana, Anthospermum rigidum, Hypoxis
iridifolia, Eriocephalus scariosus, Babiana hy-
pogea, Brachiaria serrata, Diospyros ramulosa,
Thesium lacinulatum, Wahlenbergia denticulata,
Ebracteola montis-moltkei, Tristachya superba,
Silene burchellii var. burchellii, Helichrysum ob-
tusum, Felicia muricata, Olea europaea subsp.
africana, Polygala uncinata, Cineraria canescens,
Cymbopogon caesius, Kalanchoe brachyloba,
Stoebe plumosa, Osteospermum montanum, Le-
onotis ocymifolia, Anthospermum species, Osyris
lanceolata, Searsia tenuinervis, Pegolettia retrofracta,
Sida ovata, Dicoma anomala, Danthoniopsis ramosa,
Ipomoea obscura var. obscura, Sphedamnocarpus
pruriens subsp. pruriens, Fockea angustifolia, Hy-
poestes forskaolii, Themeda triandra, Ornithoglossum
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vulgare, Gladiolus saccatus, Rhynchosia totta, Cym-
bopogon pospischilii, Andropogon chinensis, James-
brittenia lyperioides, Crassula capitella, Cotyledon
orbiculata, Gymnosporia buxifolia, Ocimum america-
num var. americanum, Moraea polystachya, Heben-
stretia integrifolia, Cyperus margaritaceus, Boophone
disticha, Gladiolus permeabilis subsp. edulis, Euphor-
bia spartaria, Aptosimum lineare, Hibiscus trionum,
Heliophila carnosa, Solanum delagoense, Jamesbrit-
tenia huillana
Constant species: Digitaria eriantha, Senegalia her-
eroensis, Tarchonanthus camphoratus, Oxalis
purpurascens, Eragrostis nindensis, Pellaea calo-
melanos, Eragrostis scopelophila, Chascanum pinnat-
ifidum, Searsia marlothii, Melinis repens subsp. rep-
ens, Heteromorpha arborescens, Commelina africana
This association is best described as a short, closed
grassland dominated by Danthoniopsis ramosa and
Heteropogon contortus, with some sparse shrub cover.
A B
C D
E F
G
Figure 6. Box-and-Whisker plots of the typical structure of the associations of the Khomas Hochland Proper, based on the relevé data.
A, Digitario erianthae–Euryopietum walterorum; B, Pennisetum foermerianum–Ficus ilicina association; C, Eriocephalo dinteri–Dan-
thoniopietum ramosae; D, Danthoniopio ramosae–Oleoetum africanae; E, Senegalio hereroensis–Tarchonanthoetum camphorati; F,
Triraphio ramosissimae–Manuleopsietum dinteri; G, Ornithoglosso calcicolae–Fingerhuthioetum africanae; H, Brachiario nigropeda-
tae–Senegalietum hereroensis.
H
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Shrubs also occur only on the lower reaches, whilst
the mountain tops are distinctly grass covered (Figures
6D and 7C). It occurs on the northern face of the Auas
Mountain range at an altitudinal range of 2 200 m asl
and above (Burke & Wittneben 2007; Strohbach 2017).
The soil surface is rock-strewn, with quarzite boulders
and solid rock of the Auas formation (Geological Survey
1980; South African Committee for Stratigraphy 1980).
MAP is between 350 and 400 mm, without taking any
orographic effects into account.
2.5 Senegalio hereroensis–
Tarchonanthoetum
camphorati ass. nov.
Synopsis:
Number of relevés: 22
Type relevé: 1123 (holotype), sampled on 25 April
2002 at 22°48’34”S, 17°02’00”E
Number of species observed: 171
Estimated number of species: 237
Average species density per 1 000 m2: 43
Diagnostic species: Sida chrysantha, Phyllanthus spe-
cies, Brachiaria nigropedata, Dyschoriste pseuderecta
Constant species: Senegalia hereroensis, Tarchonan-
thus camphoratus, Pellaea calomelanos, Melinis
repens subsp. repens, Heteropogon contortus, Era-
grostis scopelophila, Eragrostis nindensis, Digitaria
eriantha, Searsia marlothii, Hypoestes forskaolii
This tall, semi-open shrubland is dominated by Tar-
chonanthus camphoratus, Searsia marlothii and Senega-
lia hereroensis, with the grasses Brachiaria nigropedata,
Eragrostis scopelophila and Digitaria eriantha dominat-
ing the grass layer (Figures 6E and 7D). This association
occurs on the Auas Mountain and Lichtenstein ranges
at mid-altitude, between 2 000 and 2 300 m asl. No
evidence could be found for a differentiation between
north- and south-facing sides of the mountains, unlike
reported by Burke and Wittneben (2007) or Strohbach
(2017). These slopes are steep (30–60%) with consider-
able quartzite stone cover, especially medium to large
stones, even rocks (± 80% stone and rock cover), of the
Auas formation.
2.6 Triraphio ramosissimae–
Manuleopsietum dinteri ass. nov.
Synopsis:
Number of relevés: 53
Type relevé: 1011 (holotype), sampled on 16 March
2000 at 22°46’43”S, 16°46’41”E
Number of species observed: 170
Estimated number of species: 258
Average species density per 1 000 m2: 32
Diagnostic species: Pennisetum foermerianum, Triraphis
ramosissima
Constant species: Cheilanthes marlothii, Searsia mar-
lothii, Cenchrus ciliaris, Melinis repens subsp. gran-
diflora, Eragrostis nindensis, Enneapogon cenchroi-
des, Anthephora pubescens, Stipagrostis uniplumis
var. uniplumis
Typical for this short, semi-open shrubland are trees
and shrubs of Combretum apiculatum subsp. apicula-
tum, Ozoroa crassinervia, Dombeya rotundifolia and
occasionally Euphorbia avasmontana, together with
other highland savanna species. The grass layer is also
dominated by rock-specialists like Pennisetum foerme-
rianum, Triraphis ramosissima, Eragrostis scopelophila
and Danthoniopsis ramosa (Figures 6F and 7E). This as-
sociation occurs on smaller mica-schist rock outcrops
common within the central Khomas Hochland, as part
of the Kuiseb formation. These are normally between
10 × 10 to over 50 × 50 m in surface area, but always
broken, never solid rock faces. Due to the nature of the
rock beds of the Khomas Hochland, many of these rock
outcrops face south (but not exclusively). Altitude rang-
es between 1 600 and 1 800 m asl, whilst MAP ranges
between 250 and 400 mm.
Kellner (1986) distinguishes two forms of this associ-
ation, being a Pennisetum foermerianum–Dombeya
rotundifolia community on broken rock outcrops, as
well as a Triraphis ramosissima–Combretum apicula-
tum community on more solid, platy rock outcrops,
generally also with more gentle slopes. This subdivision
was neither confirmed in this study, nor by Strohbach
(2017). Volk and Leippert (1971) also describe a Com-
bretum apiculatum–Eragrostis scopelophila association,
unfortunately without proper synopsis.
2.7 Ornithoglosso calcicolae–
Fingerhuthioetum africanae ass. nov.
Synopsis:
Number of relevés: 9
Type relevé: 1095 (holotype), sampled on 23 April
2002 at 22°58’29”S, 17°07’00”E
Number of species observed: 98
Estimated number of species: 136
Average species density per 1 000 m2: 37
Diagnostic species: Ornithoglossum calcicola, Mel-
hania damarana, Monechma genistifolium, Zy-
gophyllum pubescens, Cleome suffruticosa, Sti-
pagrostis hirtigluma, Enneapogon desvauxii,
Otoptera burchellii, Leucosphaera bainesii, Eu-
phorbia lignosa, Crotalaria kurtii, Blepharis mitra-
ta, Enneapogon scoparius, Stipagrostis ciliata, Polyga-
la pallida, Fingerhuthia africana, Sericorema sericea,
Polygala leptophylla, Thesium xerophyticum, Seidelia
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A
Figure 7. Typical views of the associations of the Khomas Hoch-
land Proper. A, Digitario erianthae–Euryopietum walterorum,
relevé 1837; B, Examples of rock faces hosting the Pennise-
tum foermerianum–Ficus ilicina association, here at Midgard;
C, Danthoniopio ramosae–Oleoetum africanae on top of the
Auas Mountains; D, Senegalio hereroensis–Tarcho nanthoetum
camphorati, relevé 1123; E, Triraphio ramosissimae–Manule-
opsietum dinteri, relevé 1011; F, Ornithoglosso calcicolae–Fin-
gerhuthioetum africanae, relevé 1095; G, Brachiario nigrope-
datae–Senegalietum hereroensis, relevé 1003. Photos: C by Dr
Antje Burke, remainder by the author.
C
E
G
B
D
F
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firmula, Sarcostemma viminale, Senegalia mellifera
subsp. detinens, Hermannia abrotanoides, Erioceph-
alus luederitzianus, Croton gratissimus, Grewia flava,
Aizoon virgatum, Catophractes alexandri, Monely-
trum luederitzianum, Helinus spartioides, Pentzia
monocephala, Justicia guerkeana, Barleria lancifo-
lia, Aristida effusa, Pelargonium otaviense, Eragrostis
echinochloidea
Constant species: Searsia marlothii, Senegalia herero-
ensis, Eragrostis nindensis, Enneapogon cenchroi-
des, Talinum caffrum
This short, semi-open shrubland is dominated by the
dwarf shrub Monechma genistifolium and the grass Fin-
gerhuthia africana (Figures 6G and 7F). The occasional
occurrence of Senegalia hereroensis indicates the rela-
tionship to the central Khomas Hochland. This associ-
ation occurs on the slopes of the Oamites Mountain,
which is made up of grey quartzite and sericite phyl-
lite of the Billstein formation (Geological Survey 1980;
South African Committee for Stratigraphy 1980). The
steep to very steep slopes are covered with rocks (up to
40%) and a mixture of small, medium and large stones
(combined over 40%), at an altitudinal range of be-
tween 1 700 and 1 800 m asl, and a MAP of 350 mm.
2.8 Brachiario nigropedatae–
Senegalietum hereroensis ass. nov.
Synopsis:
Number of relevés: 238
Type relevé: 1003 (holotype), sampled on 16 March
2000 at 22°49’33”S, 16°50’00”E
Number of species observed: 287
Estimated number of species: 403
Average species density per 1 000 m2: 36
Diagnostic species: Aristida meridionalis, Gnidia poly-
cephala, Schmidtia pappophoroides, Eragrostis su-
perba, Pogonarthria fleckii
Constant species: Senegalia hereroensis, Eragrostis
nindensis, Anthephora pubescens, Searsia mar-
lothii, Melinis repens subsp. grandiflora, Brachiaria
nigropedata, Stipagrostis uniplumis var. uniplumis,
Monelytrum luederitzianum, Enneapogon cenchroi-
des, Ziziphus mucronata, Cenchrus ciliaris
These short, semi-open bushlands are dominated by
shrubs of Senegalia hereroensis, with scattered low trees
and shrubs of Tarchonanthus camphoratus, Ziziphus
mucronata, Combretum apiculatum subsp. apiculatum,
Senegalia mellifera subsp. detinens, Euclea undulata,
Vachellia tortilis, Albizia anthelmintica and Vachellia
reficiens. The grass layer is rather species-rich, with
Eragrostis nindensis, Enneapogon cenchroides, Monel-
ytrum luederitzianum, Aristida adscensionis, Cenchrus
ciliaris, Brachiaria nigropedata, Aristida meridionalis,
Melinis repens subsp. grandiflora, Anthephora pubes-
cens, Triraphis ramosissima and Stipagrostis uniplumis
var. uniplumis being the dominating species (Figures 6H
and 7G). The veld of the central Khomas Hochland oc-
curs on moderately steep to steep hills and mountains
with shallow (< 30 cm deep) soils on mica schists of
the Kuiseb Formation (Geological Survey 1980, Schnei-
der 2004). The stone cover is dominated by pebbles
and medium-sized quartz stones up to 40%, with only
occasional sub-outcropping mica schists. This associa-
tion is the most extensive association within the central
Khomas Hochland and occurs at an altitude of between
1 600 and 2 000 m asl. MAP ranges between 200 and
nearly 400 mm.
Riverine vegetation
The vegetation of the riverine habitats is dominated by
the plant families Poaceae, Asteraceae, Fabaceae and
Amaranthaceae. The classification resulted in seven as-
sociations, which are formally described according to
the International Code of Phytosociological Nomencla-
ture (Weber et al. 2000) below. The synoptic table for
these is presented in online Appendix 1, and the phy-
tosociological table in online Appendix 2.
3.1 Eragrostio rotiferi–Oleoetum
africanae ass. nov.
Synopsis:
Number of relevés: 3
Type relevé: 11525 (holotype), sampled on 16 April
2014 at 22°08’04”S, 17°17’45”E
Number of species observed: 51
Estimated number of species: 66
Average species density per 1 000 m2: 34
Diagnostic species: Olea europaea subsp. africana,
Brachylaena huillensis, Diospyros lycioides, Oxalis
purpurascens, Searsia lancea, Alternanthera nodi-
flora, Digitaria eriantha, Kohautia azurea, Gladio-
lus permeabilis subsp. edulis, Crassula capitella,
Commelina subulata, Cymbopogon pospischilii
Constant species: Ziziphus mucronata, Tagetes minu-
ta, Eragrostis rotifer, Commelina benghalensis,
Chloris virgata, Bidens biternata, Sporobolus fim-
briatus, Setaria verticillata, Schoenoplectus muric-
inux, Pogonarthria fleckii, Panicum maximum, Ox-
ygonum alatum, Melinis repens subsp. grandiflora,
Eragrostis superba, Eragrostis lehmanniana, Eragrostis
echinochloidea, Dactyloctenium aegyptium, Aspara-
gus nelsii, Achyranthes aspera, Vachellia karroo
These short, moderately closed woodlands occur in
narrow, steep-sided ravines in the Khomas Hochland,
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forming the headwaters of the rivers. The riverbed is
not well-developed, often formed by boulders and
eroded rock crevices and is generally overgrown (Fig-
ures 8A and 9A). Due to the narrowness of this bed, it
was sampled with the banks. Rock cover is up to 40%,
with considerable small, medium and large stone cover
as well. Due to the relatively small sample, no reliable
indication is available on the distribution, altitudinal
range or MAP. The sampled relevés range between
1 780 and 1 800 m asl, at a MAP of 350 mm.
3.2 Cynodo dactylonis–Eragrostioetum
rotiferi ass. nov.
Synopsis:
Number of relevés: 17
Type relevé: 11520 (holotype), sampled on 16 April
2014 at 22°06’36”S, 17°17’40”E
Number of species observed: 79
Estimated number of species: 148
Average species density per 1 000 m2: 18
Diagnostic species: Hyparrhenia hirta, Gomphostigma
virgatum, Datura inoxia, Eragrostis rotifer
Constant species: Chloris virgata, Eragrostis echinoch-
loidea, Cynodon dactylon, Cenchrus ciliaris, Eragros-
tis superba, Bidens biternata, Tagetes minuta, Melinis
repens subsp. grandiflora
As the rivers widen, a distinct near-flat, coarse sandy
bed is formed, on which this sparse short grassland es-
tablishes (Figures 8B and 9B). Depending on the flow re-
gime (fast- or slow flowing, or even standing or seepage
areas), a variety of species establish, often of ephemeral
nature. Generally, Chloris virgata, Sporobolus fimbria-
tus, Eragrostis rotifer, Eragrostis omahekensis, Eragrostis
echinochloidea and Cynodon dactylon dominate this
association. This association occurs widespread in the
study area as important part of the drainage system.
3.3 Stipagrostioetum
namaquensis ass. nov.
Synopsis:
Number of relevés: 4
Type relevé: 973 (holotype), sampled on 20 April
2000 at 22°49’08”S, 16°49’36”E
Number of species observed: 61
Estimated number of species: 83
Average species density per 1 000 m2: 30
Diagnostic species: Felicia clavipilosa, Stipagrostis na-
maquensis, Oxygonum alatum
Constant species: Pogonarthria fleckii, Acrotome
fleckii, Tragus racemosus, Tagetes minuta, Melinis re-
pens subsp. grandiflora, Melianthus comosus, Kyllinga
alata, Galenia africana, Enneapogon cenchroides,
Chloris virgata, Bulbostylis hispidula, Bidens biternata,
Vachellia karroo, Tetragonia calycina, Stachys spathu-
lata, Schmidtia kalahariensis, Schkuhria pinnata,
Ocimum americanum var. americanum, Monechma
spartioides, Limeum sulcatum, Indigofera alternans,
Hermbstaedtia odorata, Heliotropium nelsonii, Geige-
ria pectidea, Eragrostis trichophora, Eragrostis porosa,
Eragrostis omahekensis, Cucumis africanus, Cenchrus
ciliaris, Anthephora schinzii, Anthephora pubescens,
Amaranthus thunbergii, Achyranthes aspera var. sicula
Larger rivers in relatively low-gradient environments
(e.g. the Oanob) form deep sandbanks adjacent to
the main flow channels, on which this tall, moderately
closed grassland occurs (Figures 8C and 9C). Unlike the
Cynodo dactylonis–Eragrostioetum rotiferi, this associ-
ation is of more permanent nature, with Stipagrostis
namaquensis stabilising the sand bank, and allowing
sedimentation on this sand bank. This eco-engineer
also forms a suitable habitat for phanerophytic species
(commonly Vachellia karroo, but also Vachellia eriolo-
ba, Faidherbia albida and Euclea pseudebenus) to es-
tablish. The sandbanks found in the Oanob River form
the western-most occurrence of this association, with
extensive sandbanks found further east in the Seeis and
Nossob river systems. These sand banks occur within
the study area at an altitude of between 1 850 and
1 950 m asl, and a MAP of between 300 and 350 mm.
3.4 Themedio triandrae–Chloroetum
virgatae ass. nov.
Synopsis:
Number of relevés: 8
Type relevé: 939 (holotype), sampled on 10 April
2000 at 22°45’24” S, 16°52’28” E
Number of species observed: 130
Estimated number of species: 185
Average species density per 1 000 m2: 42
Diagnostic species: Tragus berteronianus, Schmidtia
pappophoroides, Themeda triandra, Talinum caf-
frum, Platycarphella carlinoides, Monsonia angus-
tifolia, Microchloa caffra, Eragrostis superba, Geige-
ria pectidea
Constant species: Chloris virgata, Eragrostis porosa,
Eragrostis echinochloidea, Anthephora pubescens,
Vachellia karroo, Ursinia nana, Tribulus zeyheri, Kyl-
linga alata, Heliotropium nelsonii, Eragrostis ninden-
sis, Aristida congesta subsp. congesta, Vachellia erio-
loba, Urochloa brachyura, Tragus racemosus, Tetrag-
onia calycina, Schkuhria pinnata, Pogonarthria fleckii,
Lycium bosciifolium, Limeum sulcatum, Eragrostis
trichophora, Eragrostis rotifer, Enneapogon cenchroi-
des, Cymbopogon pospischilii, Cenchrus ciliaris,
Acrotome fleckii
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In the low-gradient landscape of the Oanob Plateau,
but also other low-gradient areas like the Regenstein
Valley and at Neudamm, valleys have been filled with
sediments, forming a low-gradient, overgrown em-
phemeral wetland locally referred to as an omuramba
(plural – omirimbi) (King 1963, Strohbach 2008). This
forms the habitat for the Themedio triandrae–Chloro-
etum virgatae, a short, moderately-closed grassland
(Figures 8D and 9D), dominated by ephemeral species
like Geigeria pectidea, Tribulus terrestris, Chloris virgata,
Aristida hordeacea and Aristida adscensionis. Only Aris-
tida congesta subsp. congesta is a prominent perenni-
al species, whilst the name-giving Themeda triandra is
a rare species, often only occurring as remnant of the
original lush grassland described by Volk and Leippert
(1971). These authors already noted the generally poor
state of this vegetation, which is prone to degradation
and erosion. Once erosion sets in, the sediments are
soon washed away to form a low-productive riverbed
similar to the Cynodo dactylonis–Eragrostioetum rotiferi,
with shrubs and trees establishing on the sides to form
the start of the Chloro virgatae–Vachellietum karroo.
The Themedio triandrae–Chloroetum virgatae occurs at
an altitudinal range of between 1 740 and 2 200 m asl,
and at a MAP of between 300 and 400 mm.
3.5 Chloro virgatae–Vachellietum
karroo ass. nov.
Synopsis:
Number of relevés: 37
Type relevé: 11519 (holotype), sampled on 16 April
2014 at 22°06’35” S, 17°17’40” E
Number of species observed: 218
Estimated number of species: 312
Average species density per 1 000 m2: 26
Diagnostic species: Senegalia mellifera subsp. detin-
ens, Phaeoptilum spinosum, Grewia flava, Aristida ad-
scensionis, Eragrostis rigidior, Monechma divaricatum
Constant species: Vachellia karroo, Eragrostis porosa,
Enneapogon cenchroides, Eragrostis echinochloidea,
Ziziphus mucronata, Cenchrus ciliaris, Vachellia eri-
oloba, Chloris virgata, Stipagrostis uniplumis var. uni-
plumis, Pogonarthria fleckii, Melinis repens subsp.
grandiflora, Aristida congesta subsp. congesta, Bidens
biternata
These tall, closed thickets are dominated by the tree
and shrub species Vachellia karroo, Vachellia tortilis,
Senegalia mellifera subsp. detinens and Ziziphus mucro-
nata (Figures 8E and 9E). The herb layer consists of a
mixture of various species, often shade tolerant species.
The Chloro virgatae–Vachellietum karroo form the ripar-
ian forests lining most major inland rivers in the Kho-
mas Hochland and have strong affinities to the Ziziphus
mucronata–Acacia tortilis association described for the
Thornbush savanna (Strohbach 2019). Both Kellner
(1986) and Strohbach (2017) refer to the Chloro vir-
gatae–Vachellietum karroo as Cynodon dactylon–Acacia
karroo association, a name which was rejected as the
name-giving Cynodon dactylon was neither a diagnos-
tic nor constant species in this association.
The Chloro virgatae–Vachellietum karroo generally have
a steep bank towards the riverbed but are fairly flat be-
yond the bank. Stone cover is low, rather occasional,
mostly deposited by extreme flood events. This associ-
ation occurs at altitudes of between 1 540 and 1 950 m
asl, and MAP of between 250 and 400 mm.
3.6 Salvadoro persicae–Eucleetum
pseudebeno ass. nov.
Synopsis:
Number of relevés: 5
Type relevé: 1929 (holotype), sampled on 16 Febru-
ary 2004 at 23°10’21” S, 16°02’28” E
Number of species observed: 48
Estimated number of species: 66
Average species density per 1 000 m2: 21
Diagnostic species: Stipagrostis hochstetteriana, Eu-
clea pseudebenus, Salvadora persica, Tribulus
zeyheri, Portulaca oleracea
Constant species: Cenchrus ciliaris, Vachellia erioloba,
Ziziphus mucronata, Pergularia daemia, Heliotropi-
um nelsonii, Gisekia africana, Faidherbia albida, Am-
aranthus thunbergii
The Salvadoro persicae–Eucleetum pseudebeno forms
a tall, semi-open woodland dominated by Faidherbia
albida and Salvadora persica (Figures 8F and 9F). This
association form the riparian forests along the bigger
rivers in the western (Pre-Namib) part of the study area,
i.e. the middle reaches of the Swakop, Kuiseb and Gaub
rivers. The relationship to the lower Kuiseb vegetation
(Theron et al. 1980) needs to be investigated further.
The Salvadoro persicae–Eucleetum pseudebeno oc-
curs in the lower rainfall areas, with a MAP of less than
200 mm, and at altitudes less than 1 100 m asl. Simi-
lar to its inland equivalents (the Chloro virgatae–Vach-
ellietum karroo and the Setario finitae–Vachellietum
eriolobae), this association displays low slope gradients
(flat to gently undulating) with little stone cover.
3.7 Setario nitae–Vachellietum
eriolobae ass. nov.
Synopsis:
Number of relevés: 18
Type relevé: 11488 (holotype), sampled on 30
March 2014 at 22°02’29”S, 17°22’08”E
Number of species observed: 69
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Estimated number of species: 101
Average species density per 1 000 m2: 25
Diagnostic species: Setaria finita, Eragrostis cilianen-
sis, Digitaria velutina, Zehneria marlothii, Che-
nopodium petiolariforme, Cyperus squarrosus,
Sporobolus fimbriatus, Urochloa brachyura, Solanum
delagoense, Cucumis meeusei, Schmidtia kalaharien-
sis, Pechuel-Loeschea leubnitziae
Constant species: Bidens biternata, Pogonarthria
fleckii, Chloris virgata, Vachellia erioloba, Ziziphus
mucronata, Schkuhria pinnata, Cenchrus ciliaris, Bul-
bostylis hispidula, Vachellia karroo, Setaria verticillata,
Eragrostis echinochloidea, Tagetes minuta, Eragrostis
trichophora, Dactyloctenium aegyptium, Anthephora
schinzii, Amaranthus thunbergii
This tall, moderately closed woodland is found along
the banks of the big inland rivers of the Khomas Hoch-
land, notably the upper reaches of the Swakop River,
but also its tributaries like the Gammams and Otjiseva
rivers (Figures 8G and 9G). It is dominated by Ziziphus
mucronata, Vachellia karroo and Vachellia erioloba
trees, with Faidherbia albida also occurring occasionally.
The Setario finitae–Vachellietum eriolobae often forms
islands within broad riverbeds, indicating a relationship,
A B
C D
E F
G
Figure 8. Box-and-Whisker plots of the typical structure of the
riverine associations within the Khomas Hochland Proper,
based on the relevé data. A, Eragrostio rotiferi–Oleoetum
africanae; B, Cynodo dactylonis–Eragrostioetum rotiferi; C,
Stipagrostioetum namaquensis; D, Themedio triandrae–Chlo-
roetum virgatae; E, Chloro virgatae– Vachellietum karroo; F,
Salvadoro persicae–Eucleetum pseudebeno; G, Setario fini-
tae–Vachellietum eriolobae.
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A
Figure 9. Typical views of the associations of the riverine habitats
within the Khomas Hochland. A, Eragrostio rotiferi–Oleoetum
africanae, relevé 11525; B, Cynodo dactylonis–Eragrostioetum
rotiferi, relevé 11520; C, Stipagrostioetum namaquensis, relevé
973; D, Themedio triandrae–Chloroetum virgatae, relevé 939;
E, Chloro virgatae–Vachellietum karroo, relevé 11519; F, Salva-
doro persicae–Eucleetum pseudebeno, relevé 929; G, Setario
finitae–Vachellietum eriolobae, relevé 11488.
C
E
G
B
D
F
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possibly even a successional advanced stage, of the Sti-
pagrostietum namaquensis. It has been found at alti-
tudes of between 1 550 and 1 600 m asl, and MAP
range of between 300 and 400 mm.
Lowlands surrounding the
Khomas Hochland
The vegetation of the surrounding lowlands is dominat-
ed by the plant families Poaceae, Fabaceae, Asteraceae
and Amaranthaceae. Eight associations, one with four
sub-associations, were identified and are formally de-
scribed following guidelines of the ICPN below (with
one exception). Their composition is presented in Ap-
pendices 1 and 2 as synoptic and phytosociological
tables.
4.1 Pseudogaltonio clavatae–
Eriocephaloetum luederitziana ass. nov.
Synopsis:
Number of relevés: 35
Type relevé: 10624 (holotype), sampled on 18 April
2011 at 23°07’18” S, 16°54’00” E
Number of species observed: 131
Estimated number of species: 217
Average species density per 1 000 m2: 37
Diagnostic species: Stipagrostis obtusa, Senecio wind-
hoekensis, Rosenia humilis, Sporobolus nervosus,
Enneapogon desvauxii, Sida ovata, Polygala pallida,
Aizoon schellenbergii, Pentzia calva, Sericorema ser-
icea, Eragrostis echinochloidea, Melhania virescens,
Pseudogaltonia clavata, Aptosimum lineare, Leobor-
dea platycarpa, Pteronia mucronata
Constant species: Leucosphaera bainesii, Stipagrostis
uniplumis var. uniplumis, Hirpicium gazanioides, Era-
grostis nindensis, Eriocephalus luederitzianus, Finger-
huthia africana, Cenchrus ciliaris, Stipagrostis ciliata,
Eragrostis porosa, Melinis repens subsp. grandiflora,
Hermannia modesta, Barleria rigida, Vachellia eriolo-
ba, Tribulus zeyheri, Pogonarthria fleckii, Enneapogon
cenchroides
This low, moderately closed shrubland has a distinct
karoid character, being dominated by the dwarf shrub
species Eriocephalus luederitzianus, Monechma genisti-
folium, Leucosphaera bainesii and Aizoon schellenbergii
(Figures 10A and 11A). This association is limited to the
Narais plains towards Rehoboth, occurring on shallow
loamy soils on calcretes, which have formed over the
quarzites of the Duruchaus formation. Stone cover is
about 20%, mostly calcrete gravel and small stones.
Occasional deep pockets in the subsurfacing calcretes
allow Vachellia erioloba trees to establish, adding a very
sparse tree layer to this association’s structure (Jürgens
et al. 2010). This association receives between 250 and
300 mm MAP and is at an altitudinal range of between
1 580 and 1 640 m asl. The topography is generally flat.
4.2 Panico lanipedis–Pentzietum
incanae ass. nov.
Synopsis:
Number of relevés: 59
Type relevé: 1020 (holotype), sampled on 17 March
2000 at 22°48’42” S, 16°51’40” E
Number of species observed: 180
Estimated number of species: 232
Average species density per 1 000 m2: 52
Diagnostic species: Panicum lanipes, Blepharis integ-
rifolia, Eriospermum flagelliforme, Plinthus sericeus,
Pteronia eenii, Pentzia incana, Ipomoea bolusiana,
Talinum caffrum, Monelytrum luederitzianum, Com-
melina africana, Oxygonum sinuatum, Ursinia nana
Constant species: Eriocephalus luederitzianus, Era-
grostis nindensis, Senegalia mellifera subsp. det-
inens, Microchloa caffra, Kyphocarpa angustifolia,
Aristida adscensionis, Phaeoptilum spinosum, Her-
mannia modesta, Leucosphaera bainesii, Chascanum
pinnatifidum, Schmidtia pappophoroides, Barleria
rigida, Aptosimum spinescens, Melinis repens sub-
sp. grandiflora, Hirpicium gazanioides, Pogonarthria
fleckii, Hibiscus discophorus, Tragus berteronianus,
Lycium eenii, Catophractes alexandri, Stipagrostis
uniplumis var. uniplumis, Ocimum americanum var.
americanum, Fingerhuthia africana, Eragrostis porosa,
Aristida congesta subsp. congesta, Vachellia hebecla-
da subsp. hebeclada, Tarchonanthus camphoratus,
Platycarphella carlinoides, Enneapogon cenchroides,
Geigeria ornativa, Anthephora pubescens, Senegalia
hereroensis, Searsia marlothii, Raphionacme veluti-
na, Eragrostis trichophora, Cyperus palmatus
The Panico lanipedis–Pentzietum incanae varies from
a low, open to semi-open shrubland to a tall, moder-
ately-closed shrubland, depending on its state of en-
croachment by savanna species. In its natural state it
has a distinct karoid character, being dominated by
Leucosphaera bainesii and Eriocephalus luederitzianus
(Figures 10B and 11B). This association is however
prone to encroachment by specifically Senegalia mel-
lifera subsp. detinens, Catophractes alexandri and/or
Vachellia reficiens, which causes the structure to change
to a tall, denser shrubland. It occurs specifically on the
rolling to moderately steep Oanob plateau, whilst simi-
lar vegetation has been also observed on the Hoffnung
plateau east of Windhoek as well as at Neu Heusis west
of Windhoek. As with the surrounding Brachiario ni-
gropedatae–Senegalietum hereroensis, the subsurface
geology are mica schists of the Kuiseb formation. How-
ever, the landscape is a gentler, undulating to rolling
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plateau at an altitudinal range of between 1 800 and
1 900 m asl. Stone cover is about 40%, mainly by small
and medium-sized stones. MAP is between 300 and
350 mm.
4.3 Aptosimo spinescentis–
Galenietum africanae ass. nov.
Synopsis:
Number of relevés: 8
Type relevé: 2155 (holotype), sampled on 11 Febru-
ary 2005 at 23°16’25” S, 16°31’06” E
Number of species observed: 83
Estimated number of species: 136
Average species density per 1 000 m2: 32
Diagnostic species: Eriocephalus ericoides, Galenia
africana, Geigeria pectidea, Hermannia comosa,
Aptosimum spinescens
Constant species: Stipagrostis uniplumis var. uniplumis,
Eragrostis porosa, Eragrostis nindensis, Aristida adscen-
sionis, Tribulus terrestris, Platycarphella carlinoides,
Phaeoptilum spinosum, Eragrostis echinochloidea,
Stipagrostis ciliata, Pentzia calva, Ocimum america-
num var. americanum, Kohautia cynanchica, Erio-
cephalus luederitzianus, Eragrostis lehmanniana,
Enneapogon desvauxii, Enneapogon cenchroides,
Chascanum pinnatifidum, Aristida congesta subsp.
congesta, Aptosimum albomarginatum, Vachellia
erioloba
These short, semi-open shrublands are limited to the
alluvial plains around the farm Göllschau (H.E.S.S.
project) in the southwestern Khomas Hochland (Figures
10C and 11C). The plains are dominated by the grasses
Stipagrostis uniplumis var. uniplumis, Aristida adscen-
sionis and Sporobolus nervosus, whilst the dwarf shrubs
Eriocephalus ericoides and Galenia africana give it a
karoid character. Occasional trees of Vachellia erioloba
also occur here. The alluvial soils are derived from gran-
ites of the Gamsberg suite, which is sub-outcropping
here (less than 5% cover). Slopes are generally flat to
gently undulating, at an altitudinal range of 1 750 to
1 800 m asl. MAP is about 250 mm.
4.4 Panico arbusculi–Senegalietum
detinentis ass. nov.
Synopsis:
Number of relevés: 28
Type relevé: 2130 (holotype), sampled on 9 Febru-
ary 2005 at 23°05’29” S, 16°39’29” E
Number of species observed: 156
Estimated number of species: 209
Average species density per 1 000 m2: 51
Diagnostic species: Panicum arbusculum, Hibiscus
discophorus, Ipomoea obscura var. obscura, Aristida
meridionalis, Talinum arnotii, Blepharis mitrata, Bra-
chiaria nigropedata, Catophractes alexandri
Constant species: Senegalia mellifera subsp. detinens,
Leucosphaera bainesii, Kyphocarpa angustifolia,
Eragrostis nindensis, Phaeoptilum spinosum, Micro-
chloa caffra, Chascanum pinnatifidum, Stipagrostis
uniplumis var. uniplumis, Fingerhuthia africana, Gre-
wia flava, Ptycholobium biflorum, Melinis repens sub-
sp. grandiflora, Eriocephalus luederitzianus, Schmidtia
pappophoroides, Melhania virescens, Limeum myoso-
tis, Aristida adscensionis, Aptosimum albomarginatum,
Aizoon schellenbergii, Otoptera burchellii, Ocimum
americanum var. americanum, Monelytrum luederit-
zianum, Hermannia modesta, Enneapogon cenchroi-
des, Cenchrus ciliaris, Aptosimum spinescens, Lycium
eenii, Lycium bosciifolium, Hirpicium gazanioides,
Barleria rigida, Asparagus exuvialis, Searsia marlothii,
Raphionacme velutina, Phyllanthus maderaspatensis,
Antizoma angustifolia, Kyllinga alba, Dicoma capensis,
Anthephora pubescens
These tall, moderately closed shrublands are dominat-
ed by Senegalia mellifera subsp. detinens, Catophractes
alexandri, Rhigozum trichotomum and Monechma
genistifolium. The grass layer contains Panicum arbus-
culum, Stipagrostis uniplumis var. uniplumis, Melinis
repens subsp. grandiflora, Eragrostis nindensis and Aris-
tida congesta subsp. congesta (Figures 10D and 11D).
The presence of Rhigozum trichotomum and Panicum
arbusculum within this southern Khomas Hochland
is indicative of the transitional nature of these shrub-
lands to the Dwarf Shrub Savanna sensu Giess (1998)
or Nama Karoo. This association occurs on the rolling
to moderately steep hilly landscape of the southern
Khomas Hochland, and is especially well-represented
along the C26. The underlying geology is formed by the
mixtites of the Chuos Formation. Stone cover is about
40%, mainly small and medium-sized stones. The alti-
tude ranges between 1 650 and 1 850 m asl, whilst the
MAP ranges between 200 and 300 mm.
4.5 Elephantorrhizo suffruticosae–
Euphorbietum guerichianae ass. nov.
Synopsis:
Number of relevés: 24
Type relevé: 2019 (holotype), sampled on 20 Febru-
ary 2004 at 23°15’04” S, 16°19’02” E
Number of species observed: 114
Estimated number of species: 172
Average species density per 1 000 m2: 35
Diagnostic species: Euphorbia guerichiana, Heliotropi-
um nelsonii, Elephantorrhiza suffruticosa, Cheilan-
thes marlothii, Commiphora glandulosa, Setaria
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appendiculata, Helichrysum tomentosulum, Triraphis
ramosissima, Blepharis obmitrata, Tephrosia dregeana
var. dregeana, Emilia marlothiana, Anthephora pu-
bescens, Cyphostemma currorii, Ozoroa crassinervia,
Manuleopsis dinteri, Montinia caryophyllacea, Tribu-
lus zeyheri, Boscia albitrunca
Constant species: Stipagrostis uniplumis var. uni-
plumis, Otoptera burchellii, Eragrostis nindensis,
Talinum caffrum, Searsia marlothii, Fingerhuthia afri-
cana, Phaeoptilum spinosum, Hermannia modesta,
Monechma spartioides, Cenchrus ciliaris, Vachellia
reficiens, Melinis repens subsp. grandiflora, Com-
bretum apiculatum subsp. apiculatum, Chascanum
pinnatifidum, Aristida adscensionis
These short, moderately closed bushlands occur in the
upper reaches of the escarpment zone, between 1 450
and 1 780 m asl. The slopes are generally very steep
(Figures 10E and 11E). This association is dominated by
Vachellia reficiens, Elephantorrhiza suffruticosa, Senegalia
erubescens, as well as the grasses Stipagrostis uniplumis
var. uniplumis, Eragrostis nindensis and Setaria appen-
diculata. The latter again is an indication of a transition
to mountainous habitats in the Nama Karoo biome.
Geology is varied, however mostly mica schists of the
Kuiseb Formation and quarzites of the Auas formation
(Geological Survey 1980; South African Committee for
Stratigraphy 1980). Especially rock cover is high, with
up to 80% of the surface covered by large stones and/
or rocks. MAP ranges between 200 and 300 mm, not
taking any orographic effects into account.
4.6 Dichrostachyo cinereae–Senegalietum
erubescentis ass. nov.
Synopsis:
Number of relevés: 91
Type relevé: 9494 (holotype), sampled on 16 March
2009 at 22°18’10” S, 16°27’40” E
Figure 10. Box-and-Whisker plots of the typical structure of the associations of the Khomas Hochland Proper, based on the relevé data.
A, Pseudogaltonio clavatae–Eriocephaloetum luederitziana; B, Panico lanipedis–Pentzietum incanae; C, Aptosimo spinescentis–Gale-
nietum africanae; D, Panico arbusculi–Senegalietum detinentis; E, Elephantorrhizo suffruticosae–Euphorbietum guerichianae; F, Di-
chrostachyo cinereae–Senegalietum erubescentis.
A B
C D
E F
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Figure 10 (continued). Box-and-Whisker plots of the typical structure of the associations of the Khomas Hochland Proper, based on
the relevé data. G, Schmidtio kalahariensis–Vachellietum eriolobae; H, Stipagrostis uniplumis–Senegalia detinens association; I, Stipa-
grostis uniplumis–Senegalia detinens typical sub-association; J, Stipagrostis uniplumis–Senegalia detinens tarchonanthus camphoratus
sub-association; K, Stipagrostis uniplumis–Senegalia detinens vachellia tortilis sub-association; L, Stipagrostis uniplumis–Senegalia det-
inens vachellia reficiens sub-association.
G H
I J
K L
Number of species observed: 270
Estimated number of species: 383
Average species density per 1 000 m2: 39
Diagnostic species: Senegalia erubescens, Dichro-
stachys cinerea, Grewia flavescens, Combretum
apiculatum subsp. apiculatum, Hibiscus elliottiae
Constant species: Stipagrostis uniplumis var. uni-
plumis, Enneapogon cenchroides, Senegalia mellifera
subsp. detinens, Melinis repens subsp. grandiflora,
Eragrostis nindensis, Cenchrus ciliaris, Catophractes
alexandri, Vachellia reficiens, Pogonarthria fleckii, Ky-
phocarpa angustifolia, Triraphis ramosissima, Aristida
effusa, Anthephora pubescens, Pupalia lappacea, Gre-
wia flava, Boscia albitrunca, Ptycholobium biflorum
These high, moderately closed shrublands are dominat-
ed by the shrub species Senegalia erubescens, Vachellia
reficiens, Senegalia mellifera subsp. detinens, Melinis re-
pens subsp. grandiflora and Dichrostachys cinerea. The
grass layer is dominated by Enneapogon cenchroides,
Eragrostis nindensis, Stipagrostis uniplumis var. uniplumis
and Schmidtia kalahariensis (Figures 10F and 11F). This
association occurs in the rolling to moderately steep
lowlands in the Windhoek valley, as well as Swakop val-
ley around Okahandja. Some patches of this have also
been observed in the upper Kuiseb valley. The altitude
ranges between 1 300 and 1 800 m asl. Geology is var-
ied, mainly mica schists from the Kuiseb formation, but
also various intrusive granitic formations in the Swakop
valley around Okahandja. Surface stone cover reaches
between 40 and 80%, mainly small and medium stones.
MAP ranges between 200 and 350 mm.
4.7 Schmidtio kalahariensis–
Vachellietum eriolobae ass. nov.
Synopsis:
Number of relevés: 26
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Type relevé: 1082 (holotype), sampled on 22 April
2002 at 22°52’49” S, 17°06’13” E
Number of species observed: 103
Estimated number of species: 161
Average species density per 1 000 m2: 27
Diagnostic species: Schmidtia kalahariensis, Hermb-
staedtia fleckii, Eragrostis cylindriflora
Constant species: Phaeoptilum spinosum, Vachellia eri-
oloba, Stipagrostis uniplumis var. uniplumis, Enneap-
ogon cenchroides, Acrotome fleckii, Senegalia mel-
lifera subsp. detinens, Pollichia campestris, Eragrostis
porosa, Gisekia africana, Geigeria pectidea
These tall, semi-open bushlands are dominated by
Vachellia erioloba trees, interspersed by shrubs of Sen-
egalia mellifera subsp. detinens and Lycium bosciifolium.
The grass layer is dominated by Schmidtia kalahariensis
and Stipagrostis uniplumis var. uniplumis. Conspicuous
are the suffrutex Elephantorrhiza elephantina and the
forb Geigeria pectidea (Figures 10G and 11G). This as-
sociation occurs on the alluvial plains around Aris and at
Omeya south of Windhoek but has also been observed
in the Brakwater/Döbra area in the valley north of
Windhoek. The slopes are flat to gently undulating, with
hardly any stone cover (mostly gravel and small stones,
less than 2%). The altitude ranges between 1 600 and
1 770 m asl, with MAP of between 300 and 350 mm.
4.8 Stipagrostis uniplumis–Senegalia
detinens association
Synopsis:
Number of relevés: 162
Number of species observed: 317
Estimated number of species: 473
Average species density per 1 000 m2: 41
Diagnostic species: none
Constant species: Senegalia mellifera subsp. detinens,
Stipagrostis uniplumis var. uniplumis, Enneapogon
cenchroides, Kyphocarpa angustifolia, Cenchrus cili-
aris, Ocimum americanum var. americanum, Melinis
repens subsp. grandiflora, Eragrostis nindensis, Cato-
phractes alexandri, Eragrostis porosa, Grewia flava,
Boscia albitrunca, Aristida adscensionis, Ziziphus
mucronata, Lycium bosciifolium, Otoptera burchellii,
Phaeoptilum spinosum, Pogonarthria fleckii, Pty-
cholobium biflorum
These tall, semi-open shrublands are dominated by Sen-
egalia mellifera subsp. detinens, Catophractes alexandri,
Vachellia reficiens and Phaeoptilum spinosum (Figure
10H). This association is often associated with degra-
dation within various units in the Khomas Hochland,
but also the regular Thornbush savanna elements to the
east and north of the Khomas Hochland. Although four
distinct forms have been recognised (and described as
sub-associations below), there is still sufficient uncer-
tainty regarding the classification not to allow a formal
description of these communities yet.
4.8.1 Stipagrostis uniplumis–Senegalia
detinens typical sub-association
Synopsis:
Number of relevés: 46
Number of species observed: 193
Estimated number of species: 286
Average species density per 1 000 m2: 42
Diagnostic species: none
Constant species: Stipagrostis uniplumis var. uni-
plumis, Phaeoptilum spinosum, Senegalia mellifera
subsp. detinens, Ocimum americanum var. america-
num, Eragrostis nindensis, Kyphocarpa angustifolia,
Grewia flava, Enneapogon cenchroides, Schmidtia
pappophoroides, Talinum caffrum, Hirpicium gaza-
nioides, Otoptera burchellii, Catophractes alexandri,
Aristida congesta subsp. congesta, Ziziphus mucrona-
ta, Hermannia modesta, Vachellia hebeclada subsp.
hebeclada, Kyllinga alba, Gisekia africana, Aristida
adscensionis, Indigofera vicioides, Eragrostis porosa,
Dicoma capensis, Cenchrus ciliaris, Boscia albitrunca,
Lycium eenii, Chascanum pinnatifidum
These tall, semi-open shrublands are the typical form
of the Stipagrostis uniplumis–Senegalia detinens associ-
ation (Figures 10I and 11H). Strohbach (2017) referred
to this as the ‘Pupalia lappacea–Acacia mellifera bush
encroached lowlands’, indicating that this association is
often a degradation state of other associations. As Pupa-
lia lappacea however was not found to be a diagnostic
nor constant species, the proposed name was rejected.
This sub-association is found as patches in various com-
ponents and associations within the Khomas Hochland.
Especially the Brachiario nigropedatae–Senegalietum
hereroensis, the Panico arbusculi–Senegalietum det-
inentis and the Panico lanipedis–Pentzietum incanae
seem prone to degradation to this state.
The Stipagrostis uniplumis–Senegalia detinens typical
sub-association occurs on undulating to rolling slopes,
often with up to 40% gravel and small stone cover, at
altitudinal ranges between 1 650 and 1 800 m asl.
4.8.2 Stipagrostis uniplumis–Senegalia
detinens tarchonanthus
camphoratus sub-association
Synopsis:
Number of relevés: 35
Number of species observed: 194
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Estimated number of species: 300
Average species density per 1 000 m2: 42
Diagnostic species: Tarchonanthus camphoratus
Constant species: Senegalia mellifera subsp. detinens,
Stipagrostis uniplumis var. uniplumis, Enneapogon
cenchroides, Ocimum americanum var. americanum,
Cenchrus ciliaris, Boscia albitrunca, Phaeoptilum spi-
nosum, Lycium eenii, Ziziphus mucronata, Schmid-
tia pappophoroides, Otoptera burchellii, Grewia
flava, Eragrostis porosa, Eragrostis nindensis, Achy-
ranthes aspera var. sicula, Searsia marlothii, Pavo-
nia burchellii, Catophractes alexandri, Kyphocarpa
angustifolia, Vachellia erioloba, Pogonarthria fleckii,
Monechma spartioides, Melinis repens subsp. grandi-
flora, Hermannia modesta, Talinum caffrum, Leuco-
sphaera bainesii, Leucas pechuelii, Gisekia africana,
Eragrostis echinochloidea, Ehretia rigida
These high, semi-open shrublands are also dominated
by Senegalia mellifera subsp. detinens and Catophractes
alexandri (Figures 10J and 11I). The occurrence of Tar-
chonanthus camphoratus indicates slightly moister con-
ditions, reflected in deeper, sandier soils, but also higher
rainfall regimes (between 350 and 400 mm MAP). This
sub-association is found in the eastern parts of the study
area, linking into the thornbush savanna types to the
east of Windhoek. The altitude ranges between 1 550
and 1 830 m asl, with rolling to moderately steep slopes.
The subsurface geology are granites and gneiss from the
Hohewarte complex and Gamsberg Suite. Stone cover
is low (< 15%), mostly gravel and small stones.
4.8.3 Stipagrostis uniplumis–
Senegalia detinens vachellia
tortilis sub-association
Synopsis:
Number of relevés: 12
Number of species observed: 156
Estimated number of species: 267
Average species density per 1 000 m2: 39
Diagnostic species: none
Constant species: Melinis repens subsp. grandiflo-
ra, Enneapogon cenchroides, Cenchrus ciliaris,
Pogonarthria fleckii, Eragrostis porosa, Ziziphus mu-
cronata, Stipagrostis uniplumis var. uniplumis, Era-
grostis nindensis, Senegalia mellifera subsp. detinens,
Searsia marlothii, Phaeoptilum spinosum, Aristida
adscensionis, Anthephora pubescens, Triraphis ra-
mosissima, Schmidtia pappophoroides, Eragrostis
rigidior, Aristida congesta subsp. congesta, Ocimum
americanum var. americanum, Nidorella resedifolia,
Monechma divaricatum, Lycium bosciifolium, Era-
grostis echinochloidea
These short, semi-open bushlands are dominated by
Vachellia reficiens, Senegalia mellifera subsp. detinens
and Vachellia tortilis (Figure 10K). It has a limited oc-
currence in patches in the Khomas Hochland and has
mainly been observed west of Windhoek in the Daan
Viljoen Game Reserve. This sub-association occurs on
moderately steep to steep slopes at altitudinal ranges
between 1 500 and 1 800 m asl. Stone cover is fair-
ly high, above 40%, mostly small and medium stones.
Larger stones, and occasional rock outcrops, are also
present. The subsurface geology is also mica-schists of
the Kuiseb Formation.
4.8.4 Stipagrostis uniplumis–
Senegalia detinens vachellia
reciens sub-association
Synopsis:
Number of relevés: 69
Type relevé: 9504 (holotype), sampled on 16 March
2009 at 21°55’51” S, 16°34’36” E
Number of species observed: 219
Estimated number of species: 341
Average species density per 1 000 m2: 39
Diagnostic species: none
Constant species: Senegalia mellifera subsp. detinens,
Stipagrostis uniplumis var. uniplumis, Vachellia
reficiens, Enneapogon cenchroides, Lycium boscii-
folium, Melinis repens subsp. grandiflora, Albizia an-
thelmintica, Kyphocarpa angustifolia, Catophractes
alexandri, Aristida adscensionis, Cenchrus ciliaris,
Ptycholobium biflorum, Eragrostis porosa, Boscia al-
bitrunca, Aristida effusa, Pupalia lappacea, Schmidtia
kalahariensis, Leucosphaera bainesii, Pogonarthria
fleckii, Commelina benghalensis, Ocimum america-
num var. americanum, Achyranthes aspera var. sicula
These short, moderately closed bushlands are dominat-
ed by Senegalia mellifera subsp. detinens, Vachellia refi-
ciens and Catophractes alexandri (Figures 10L and 11J).
The grass layer is dominated by Schmidtia kalahariensis,
Enneapogon cenchroides, Stipagrostis uniplumis var.
uniplumis and Aristida adscensionis. This sub-association
occurs in mosaic with the Dichrostachyo cinereae–
Senegalietum erubescentis in the Windhoek valley and
the Swakop Valley to the west of Okahandja. The rela-
tionship between these two syntaxa is not clear.
The Stipagrostis uniplumis–Senegalia detinens vachellia
reficiens sub-association occurs at an altitudinal range
of between 1 500 and 1 800 m asl, on rolling to mod-
erately steep slopes. Geology is varied, mostly mica
schists and granites. Stone cover is mostly by gravel,
small and medium sized stones, less than 40%. MAP
ranges between 200 and 400 mm.
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A
Figure 11. Typical views of the associations of the Khomas Hochland Proper. A, Pseudogaltonio clavatae–Eriocephaloetum luederitziana;
B, Panico lanipedis–Pentzietum incanae, relevé 1020; C, Aptosimo spinescentis–Galenietum africanae, relevé 2155; D, Panico arbus-
culi–Senegalietum detinentis, relevé 2153; E, Elephantorrhizo suffruticosae–Euphorbietum guerichianae, relevé 2017; F, Dichrostachyo
cinereae–Senegalietum erubescentis, relevé 9494; G, Schmidtio kalahariensis–Vachellietum eriolobae, relevé 1082; H, Stipagrostis uni-
plumis–Senegalia detinens typical sub-association, relevé 982; I, Stipagrostis uniplumis–Senegalia detinens tarchonanthus camphoratus
sub-association, relevé 1146; J, Stipagrostis uniplumis–Senegalia detinens vachellia reficiens sub-association, relevé 9504.
B
C D
E F
G H
I J
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Higher syntaxonomy
The classification of the synoptic relevés of 30 associa-
tions yielded a classification with crispness peaks at 4,
8, and 14/15 divisions. Accordingly, a classification with
15 clusters was accepted and interpreted. The 15 clus-
ters were interpreted as alliances, whilst these alliances
were grouped into orders between level 4 and level 8
divisions (Figure 12). An overview of associations, asso-
ciated with their relevant alliances, orders and broad
habitats are given in Table 3.
The Senegalio hereroensis–Tarchonanthoetalia cam-
phorati is typified by the Senegalio hereroensis–Tar-
chonanthion camphorati. This order represents the high
mountains of central Namibia. Based on the present
data, it can be subdivided into two alliances, being the
Senegalio hereroensis–Tarchonanthion camphorati, rep-
resenting the Auas Mountains, as well as the Digitario
erianthae–Euryion walterorum, representing the Gams-
berg Mountain. The Senegalio hereroensis–Tarchon-
anthion camphorati is typified by the Senegalio her-
eroensis–Tarchonanthoetum camphorati and contains
also the two other associations occurring on the Auas
Mountains. The Digitario erianthae–Euryion waltero-
rum is typified by the Digitario erianthae–Euryopietum
walterorum and contains only this association.
The Cynodo dactylonis–Eragrostioetalia rotiferi is rec-
ognised as a provisional order representing the riverine
habitats. According to the present classification, it breaks
up into five alliances, each representing a single associ-
ation. Due to this, and as other, similar habitats exist in
central and southern Namibia, this provisional order is
not yet formally described pending a thorough revision.
The Brachiario nigropedatae–Senegalietalia hereroensis is
typified by the Brachiario nigropedatae–Senegalion her-
eroensis, which is also the only alliance to this order. This
order represents the vegetation of the central Khomas
Hochland. The Brachiario nigropedatae–Senegalion her-
eroensis in turn is typified by the Brachiario nigropeda-
tae–Senegalietum hereroensis. In addition to the typical
association, three other associations have been grouped
into this alliance. Two of these represent rocky habitats
typical for the central Khomas Hochland, the third rep-
resents smaller rivers within the Khomas Hochland.
The sandy and/or specialised habitats in desert environ-
ment form a cluster of associations, each being repre-
sented by an own alliance, and possibly (depending on
interpretation), even own orders. One of these associ-
ations, the Salvadoro persicae– Eucleetum pseudebeno,
could possibly also be grouped with the Cynodo dac-
tylonis– Eragrostioetalia rotiferi due to its habitat. This
is speculative, and subject to review in future. Because
of this, no formal higher syntaxonomic groupings are
described here.
The Eragrostio nindensis–Vachellietalia reficientis is typ-
ified by the Eragrostio nindensis–Vachellion reficientis.
This order represents the Pre-Namib as well as the es-
carpment zone. The classification does not present any
evidence of this order to be split into two alliances, yet,
based on the habitat and vegetation of the associations
in this order, a split was made between the name-giv-
ing alliance and the Enneapogono desvauxii–Eragrostion
nindensis. The Eragrostio nindensis–Vachellion reficien-
tis is typified by the Eragrostio nindensis–Vachellietum
reficientis and includes two other association within the
escarpment zone. The Enneapogono desvauxii–Eragros-
tion nindensis is typified by the Enneapogono desvauxii–
Eragrostietum nindensis and includes the closely related
Enneapogono desvauxii–Adenoloboetum pechuelii, as
part of the Pro-Namib landscape.
The Panico arbusculi–Senegalietalia detinentis is typified
by the Panico arbusculi–Senegalion detinentis. It includes
Figure 12. Dendrogram of the classification of synoptic relevés representing various associations. Groupings above the stippled line were
interpreted as orders, whilst the final groupings were interpreted as alliances.
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Association Alliance Order
2.1 Digitario erianthae–
Euryopietum walterorum
Digitario erianthae–
Euryion walterorum
Senegalio hereroensis–
Tarchonanthoetalia camphorati
2.3 Eriocephalo dinteri–
Danthoniopietum ramosae
Senegalio hereroensis–
Tarchonanthion camphorati High Mountains
2.5 Senegalio hereroensis–
Tarchonanthoetum camphorati Auas Mountains
2.4 Danthoniopio ramosae–
Oleoetum africanae
3.1 Eragrostio rotiferi–
Oleoetum africanae
Cynodo dactylonis–
Eragrostioetalia rotiferi
3.7 Setario finitae–Vachellietum eriolobae Rivers
3.3 Stipagrostioetum namaquensis
3.2 Cynodo dactylonis–
Eragrostioetum rotiferi
3.4 Themedio triandrae–
Chloroetum virgatae
2.2 Pennisetum foermerianum–
Ficus ilicina association
Brachiario nigropedatae–
Senegalion hereroensis
Brachiario nigropedatae–
Senegalietalia hereroensis
2.6 Triraphio ramosissimae–
Manuleopsietum dinteri
Khomas Hochland proper Khomas Hochland proper
3.5 Chloro virgatae–
Vachellietum karroo
2.8 Brachiario nigropedatae–
Senegalietum hereroensis
1.4 Tribulocarpo dimorphantho–
Vachellietum eriolobae
1.3 Crotalario podocarpae–
Stipagrostioetum obtusae
Sandy and/or specialised habitats in
desert environment
3.6 Salvadoro persicae–
Eucleetum pseudebeno
1.1 Enneapogono desvauxii–
Adenoloboetum pechuelii
Enneapogono desvauxii–
Eragrostion nindensis
Eragrostio nindensis–
Vachellietalia reficientis
1.2 Enneapogono desvauxii–
Eragrostietum nindensis Pre-Namib Desert & escarpment
1.6 Myrothamno flabellifolii–
Commiphoroetum dinteri
Eragrostio nindensis–
Vachellion reficientis
1.5 Geigerio acaulis–
Commiphoroetum glaucescentis Escarpment
1.7 Eragrostio nindensis–
Vachellietum reficientis
2.7 Ornithoglosso calcicolae–
Fingerhuthioetum africanae
Elephantorrhizo suffruticosa–
Euphorbion guerichianae
Panico arbusculi–
Senegalietalia detinentis
4.5 Elephantorrhizo suffruticosae–
Euphorbietum guerichianae
Mountainous fringes of the Khomas
Hochland
Lowlands along the Khomas
Hochland fringes
4.7 Schmidtio kalahariensis–
Vachellietum eriolobae
Panico arbusculi–
Senegalion detinentis
Table 3. Overview of the higher syntaxonomy of associations described in this study
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two other alliances, being the Elephantorrhizo suffruti-
cosae–Euphorbion guerichianae and the Dichrostachyo
cinereae–Senegalion erubescentis. This order represents
the fringes to the Khomas Hochland to the south, east,
north and, in the form of the upper escarpment, west.
The Panico arbusculi–Senegalion detinentis in turn is
typified by the Panico arbusculi–Senegalietum detinen-
tis, and, together with four other associations, forms
the transition to the Nama Karoo biome to the south.
The Schmidtio kalahariensis–Vachellietum eriolobae is
closely related to the vegetation of the southern Kala-
hari (Strohbach et al. 2019).
The Elephantorrhizo suffruticosae–Euphorbion guerichi-
anae is typified Elephantorrhizo suffruticosae–Euphor-
bietum guerichianae and represents the mountainous
habitats along the southern and western fringes of the
Khomas Hochland. It contains one other association,
the Ornithoglosso calcicolae–Fingerhuthioetum afri-
canae of the Oamites mountain.
The Dichrostachyo cinereae–Senegalion erubescentis is
typified by the Dichrostachyo cinereae–Senegalietum
erubescentis and includes the as yet not formally de-
scribed Stipagrostis uniplumis–Senegalia detinens asso-
ciation. This alliance represents the northern and east-
ern lowlands associated with the Khomas Hochland.
Discussion and
conclusion
The higher syntaxonomy confirmed several preliminary
observations. The initial classification into Pre-Namib
and Escarpment, Khomas Hochland proper, Riverine
habitats as well as surrounding lowlands are largely re-
flected in the orders Cynodo dactylonis–Eragrostioetalia
rotiferi, the Brachiario nigropedatae–Senegalietalia her-
eroensis, the Eragrostio nindensis–Vachellietalia reficientis
and the Panico arbusculi–Senegalietalia detinentis. This is
also in line with the groupings proposed by Giess (1998),
i.e. the Central Namib, the Desert transition and escarp-
ment Zone as well as the Highland savanna.
A notable exception is the Senegalio hereroensis–Tar-
chonanthoetalia camphorati (high mountains), which is
highlighted as a grouping on its own. This also confirms
the findings of Strohbach (2017), who has highlighted
the high Auas Mountain vegetation as a separate group-
ing. The Senegalio hereroensis–Tarchonanthoetalia cam-
phorati has close affinities to the grassland biome of
South Africa, with its dominant cover of grasses, in par-
ticular Digitaria eriantha (Mucina & Rutherford 2006).
Prominent representatives of the Asteraceae in this or-
der, amongst others Eriocephalus spp., Stoebe plumosa
and Euryops walterorum, also have close relatives in the
grasslands and adjacent Karoo vegetation in South Af-
rica (cf. Nordenstam 1966; Müller et al. 2001; Njenga
2005), indicating a biogeographic relationship to these
biomes, rather than the surrounding savanna biome.
The other notable exception is the formation of a clus-
ter of specialised habitats within the desert biome en-
vironment. Although the Salvadoro persicae–Eucleetum
pseudebeno has distinct affinities to the inland rivers, it
still groups into the desert environment rather than the
inland savanna environment. Of the other two associ-
ations in this cluster, the Crotalario podocarpae–Stipa-
grostioetum obtusae has affinities to the arid grasslands
of the Nama Karoo biome (Mucina & Rutherford 2006),
whilst the Tribulocarpo dimorphantho–Vachellietum eri-
olobae has affinities to the Kalahari duneveld sensu Mu-
cina and Rutherford (2006) or southern Kalahari sensu
Giess (1998).
The vegetation classification and description presented
in this paper represents a broad overview, as dictated
by the ‘reconnaissance level’ scale. Intensified sampling
in several specialist habitats, e.g. the riverine habitats,
Association Alliance Order
4.1 Pseudogaltonio clavatae–
Eriocephaloetum luederitziana
4.3 Aptosimo spinescentis–
Galenietum africanae
Southern fringe communities –
ecotone to Nama Karoo
4.4 Panico arbusculi–
Senegalietum detinentis
4.2 Panico lanipedis–
Pentzietum incanae
4.6 Dichrostachyo cinereae–
Senegalietum erubescentis
Dichrostachyo cinereae–
Senegalion erubescentis
4.8 Stipagrostis uniplumis–
Senegalia detinens association
Northern and eastern fringe lowlands
Table 3. Overview of the higher syntaxonomy of associations described in this study (continued)
Page 31 of 34
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| Open accesshttp://abcjournal.org |
the high mountains (in particular the Hakos mountains,
as well as ranges like the Bismark Mountains east of the
Auas and various ranges of the Kamtsas and Sinclair for-
mations south of Windhoek) and the Matchless Mem-
ber dissecting the central Khomas Hochland, will likely
yield further associations. The higher syntaxonomy will
likely also be clarified and strengthened once more
such studies are available and included in the analysis.
Acknowledgements
I would like to acknowledge the permission granted by
many farmers to work on their properties, as well as
the hospitality afforded by these. Tuhafeni Sheuyange,
Zuna September and Salomé Kruger assisted with the
data collection, whilst the data contributed by Coleen
Mannheimer, Martin Wittneben and Dr Antje Burke is
gratefully acknowledged. The staff of the National Her-
barium of Namibia (WIND) helped with the identifi-
cation of numerous specimens. The project was finan-
cially supported by the recurrent budget of the Ministry
of Agriculture, Water and Forestry (Vote 2004) as well
as the BIOTA southern Africa Project, in turn funded
by the German Federal Ministry of Education and Re-
search under their promotion number 01LC0624.
Competing interests:
The author declares that he has no financial or personal
relationship that may have inappropriately influenced
him in writing this article.
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Synoptic table for the Pre-Namib and Escarpment Zone communities,
with delity (phi coeff.) and frequncy of occurence (%)
Available online only DOI: http://dx.doi.org/10.38201/btha.abc.v51.i2.s4a.
Appendix 1
Phytosociological Table
Available online only DOI: http://dx.doi.org/10.38201/btha.abc.v51.i2.s4b.
Appendix 2
Page 34 of 34
