Ecosystem Guidelines for Environmental Assessment

RENOSTERVELD
Urban expansion is a problem in some areas. Urban development in adjacent areas can have a
negative impact on the maintenance of an appropriate fire regime. When fires start they are often put
out and not allowed to burn (resulting in dominance by slower growing, woody species, to the detriment
of bulbs, herbs, and grasses). In other cases, fires are often deliberately set, resulting in too-frequent
burns; slower-growing reseeding species will be lost from the system.
Drainage of seasonal wetlands destroys alluvial renosterveld habitat.
Trampling, such as by livestock, can result in the irreversible transformation of silcrete, ferricrete
and quartz patches.
Spraying of crops with insecticides may lead to the killing of pollinators of specialised plant species.
The introduction of ostriches and other extra-limital game species into renosterveld can alter grazing
regimes and result in trampling and damage to the biogenic surface. Ostriches are often introduced
after wheat fields have been harvested and they can utilize remnant renosterveld patches heavily.
Changes in the natural fire and grazing regimes (and the fine balance between them) will alter the
species richness of all renosterveld types.
Fields are often burned to remove stubble. These fires may impact on adjacent renosterveld if burnt
too frequently.
Renosterveld types are susceptible to invasion by annual alien grasses that replace bulbs. This is
probably due to a mixture of eutrophication and herbicides, coupled with inappropriate grazing, but
the details of this are not understood.
Most renosterveld types are prone to soil erosion; physical disturbance of remaining intact examples
of renosterveld should be limited to the minimum.
When crops are sprayed (especially by aeroplane), renosterveld patches and their insect populations
can be exposed to drift of herbicides and insecticides.
Many landowners do not burn remnant renosterveld patches due to fear that fires may spread.
Managed burns must be carefully controlled.
Many of the non-toxic geophytes and annuals are vulnerable to grazing pressure by domestic stock
in the first two years after a fire.
What are the “bottom lines” and non-negotiables
No more transformation is desirable in areas with intact, high quality vegetation. Habitat conversion
must be avoided and strongly discouraged in threatened renosterveld.
Plans to transform renosterveld should always be preceded by a botanical evaluation. Small
remnants (~1 ha) can be very important for the conservation of individual species and achieving some
pattern targets. However, in order to be functionally viable,
larger patches should be within 500 m of each other and The Endangered geometric tortoise Psammobates
connected by pollinator-friendly terrain.
geometricus: a renosterveld endemic.
It is critical to maintain pollinator-plant associations and
pollution by herbicides, fertilisers and insecticide spray
must be minimised.
Avoid perturbations (including grazing and all forms of
physical transformation) to silcrete, ferricrete and quartz
patches.
Appropriate fire regimes must be maintained.
Alien species should be eradicated.
Extra-limital game species should not be introduced to
renosterveld.
BOTANICAL SOCIETY OF SOUTH AFRICA
54 : RENOSTERVELD ECOSYSTEMS