the richtersveld cultural and botanical landscape - SAHRA

Richtersveld Cultural and Botanical Landscape World Heritage Site Nomination 42
it is restricted to specific geomorphological locations, e.g. limited to the pediment
west of the main mountains and to locations along the river beds, which are both
protected against deflation by strong winds, e.g. in the Numees area. The small
northeastern part of this area is underlain by granites of the Vioolsdrif Suite, the rest
occurs on Cenozoic alluvium, aeolian sand and calcrete; loamy or silty soils, which
are, as a rule, formed by aeolian deposition; not deeper than 40 cm below the
surface calcrete layers or other calcium carbonate accumulations. Often the soils
also show high salinity. The silt component is subject to local aeolian erosion and
sedimentation, resulting in erosion in the bare areas between the bushes and silt
deposition underneath the bushes - these biogenic mounds regularly attract ants
and termites.
Due to the wide range of the unit, also a wide spectrum of climatic conditions can
be found. The predominantly winter annual rainfall may vary from 50 - 100 mm. Fog
can be important, but not east of the Vandersterrberge. A few days of frost per year
can occur in the units of higher altitude, for instance on the Koeroegabvlakte.
Similarly, temperatures can follow a wide spectrum. However, in the northeastern
Richtersveld, well developed Scorpionstailveld is seldom found in the hotter areas
below an altitude of 330 m.
Brownanthus pseudoschlichtianus (the vernacular name, “scorpion’s tail”, referring
to the segmented stems) is typically dominant and forms low “cussion-like” plants of
1 to 1.5 m in diameter with interspaces of 1 to 3 m. In between the plants of B.
pseudoschlichtianus, numerous other species co-exist, some of them with high
predictability, such as the geophyte Trachyandra muricata. Most of the Northern
Richtersveld Scorpionstailveld is covered by a regular pattern of heuweltjies, which
mostly are inhabited by Mesembryanthemum hypertrophicum, M. squamulosum, M.
pellitum and Psilocaulon subnodosum.
Aside from the Conservancy, 20% of this unit is statutorily conserved in the
Richtersveld National Park. It is susceptible to grazing pressures and more
protection is recommended for this unit.