demonstrated how specific techniques could be implemented to re-establish
indigenous plant species after the cessation of mining.
Namdeb Diamond Corporation (Pty) Ltd. identified a stretch of coastline for
present and future mining activities that consists of sandy beach deposits, referred
to as the ‘‘Pocket Beach’’ areas, i.e., sediment-filled embayments situated between
headlands (Burke et al. 2002).
The southern part of the Sperrgebiet has an average annual rainfall of
10–89 mm (Pallet 1995). Rain, falling mainly in the winter months, is essential for
the germination of plants, and moisture from fog can maintain growth of perennial
plants for many years (Seely, unpublished report). Fog, with a mean occurrence of
89 days per year, is important as a source of moisture, an effect that is enhanced by
the prevailing low temperatures in the coastal region. Wind has a major influence
on coastal vegetation (Seely, unpublished report) with velocities being highest in
summer, and wind speeds ranging between 30 and 80 km h
-1 (Williamson 1997).
In the Sperrgebiet, mining has had a significant impact on coastal dune vegetation—characterized by Salsola nollothensis and Cladoraphis cyperoides hummocks
(Fig. 13.7)—and on sand plain vegetation: ‘‘dwarf shrubland’’ dominated by
Amphibolia rupis-arcuatae and Othonna furcata (Fig. 13.6) (Burke 1997). Van der
Merwe (2005) investigated the efficacy of transplanting Othonna fuscata as a means
of re-establishing the natural dwarf shrubland.
13.2.2.3 Methods
Plot Designs and Experimental Conditions
At Pocket Beach Site 2 (Fig. 13.1) 48 plots measuring 25 9 15 m were laid in 16
sets of 3, in a rectangular shape with the longest axis of each plot being perpendicular to the prevailing wind from the south (Fig. 13.7). Plots were constructed on
a mined-out area using a split-plot design to investigate different methods of
rehabilitation. In the first split-plot, the presence or absence of nets and their
effectiveness as windbreaks was tested. In other tests three different substrate types
(‘‘landscaped,’’ ‘‘flat,’’ and ‘‘pebbled’’) were incorporated into the design, which is
summarized in Fig. 13.7.
In addition to those involving the above variables, further tests were carried out
to assess the impact of applying a hydrogel to the roots of Othonna furcata.
Ninety-six O. furcata specimens, salvaged from three different locations, were
transplanted into the plots. The experiment commenced in August 2004,
coinciding with the dormancy period—from late spring into summer (Anon
2004)—so that the transplant shock would be reduced. The growth of transplanted
specimens, changes in sand accumulation, and counts of invading germinating
plants in the plots were recorded over a period of 12 months until August 2005.
13 Restoration of Dune Ecosystems Following Mining in Madagascar and Namibia
209
indigenous plant species after the cessation of mining.
Namdeb Diamond Corporation (Pty) Ltd. identified a stretch of coastline for
present and future mining activities that consists of sandy beach deposits, referred
to as the ‘‘Pocket Beach’’ areas, i.e., sediment-filled embayments situated between
headlands (Burke et al. 2002).
The southern part of the Sperrgebiet has an average annual rainfall of
10–89 mm (Pallet 1995). Rain, falling mainly in the winter months, is essential for
the germination of plants, and moisture from fog can maintain growth of perennial
plants for many years (Seely, unpublished report). Fog, with a mean occurrence of
89 days per year, is important as a source of moisture, an effect that is enhanced by
the prevailing low temperatures in the coastal region. Wind has a major influence
on coastal vegetation (Seely, unpublished report) with velocities being highest in
summer, and wind speeds ranging between 30 and 80 km h
-1 (Williamson 1997).
In the Sperrgebiet, mining has had a significant impact on coastal dune vegetation—characterized by Salsola nollothensis and Cladoraphis cyperoides hummocks
(Fig. 13.7)—and on sand plain vegetation: ‘‘dwarf shrubland’’ dominated by
Amphibolia rupis-arcuatae and Othonna furcata (Fig. 13.6) (Burke 1997). Van der
Merwe (2005) investigated the efficacy of transplanting Othonna fuscata as a means
of re-establishing the natural dwarf shrubland.
13.2.2.3 Methods
Plot Designs and Experimental Conditions
At Pocket Beach Site 2 (Fig. 13.1) 48 plots measuring 25 9 15 m were laid in 16
sets of 3, in a rectangular shape with the longest axis of each plot being perpendicular to the prevailing wind from the south (Fig. 13.7). Plots were constructed on
a mined-out area using a split-plot design to investigate different methods of
rehabilitation. In the first split-plot, the presence or absence of nets and their
effectiveness as windbreaks was tested. In other tests three different substrate types
(‘‘landscaped,’’ ‘‘flat,’’ and ‘‘pebbled’’) were incorporated into the design, which is
summarized in Fig. 13.7.
In addition to those involving the above variables, further tests were carried out
to assess the impact of applying a hydrogel to the roots of Othonna furcata.
Ninety-six O. furcata specimens, salvaged from three different locations, were
transplanted into the plots. The experiment commenced in August 2004,
coinciding with the dormancy period—from late spring into summer (Anon
2004)—so that the transplant shock would be reduced. The growth of transplanted
specimens, changes in sand accumulation, and counts of invading germinating
plants in the plots were recorded over a period of 12 months until August 2005.
13 Restoration of Dune Ecosystems Following Mining in Madagascar and Namibia
209