REHABILITATION: REHABILITATION: A QUICK GUIDE A ... - saobc

2.5.4 STEP 4 – SEEDING:
Seeding: Seeding the shaped and stabilized slopes should occur once the
geotextile has been fixed into place. Seeding prior to the fitting of the geotextile
may result in the seeds being pressed too deeply into the soil during the laying and
pegging process. The recommended plants to use for seeding as well as planting,
are given in Section 4.7 later in this report.
2.5.5 STEP 5 – MULCHING:
Once the newly shaped slope has been stabilized with a layer of the geotextile and
is seeded, the site is ready for mulching. In some parts of the study area, a handy
and nearby source of excellent mulch is the abundant Acacia karroo trees which
occur along drainages. The thorn trees are a valuable renewable resource and if
carefully harvested will leave no visible impact or have any adverse ecological
impact. When cut down, the trees readily coppice and quickly replace the stems
and branches lost. A source of mulch is always something of a problem in the Little
Karoo. If not enough material is available from the veld, then it is suggested that an
alternative source of mulch material be found. Alien gum trees and pepper trees
which are abundant in the area can be sourced. Care must, however, be taken to
apply mulch from these trees only once dried out, as the live branches and leaves
have an allelopathic (chemical) impact on soil.
Another potential source of mulch is Spanish reed, but it must be roughly cut,
otherwise it blows away in windy weather if too fine. Although finding suitable, and
enough, mulch material is a problem in the area; every effort must be made to
provide adequate mulch material because of the important function that it has in the
rehabilitation process.
Harvesting can be done by cutting down every third or fourth tree or large shrub,
about 300mm above ground level, in densely bushed areas. Along drainages, trees
that are displaced by shaping can be used. Along the undisturbed drainages, a
selective approach, removing only some of the trees will ensure that the habitat is
not too drastically altered.
While the preparation work of topsoil removal and stockpiling is done and while the
gulley sides are being shaped, a team of workers can be put onto the cutting out of
thorn trees for mulch. By cutting in a wide area around each site to be mulched, the
complete removal of thorn trees on site is avoided. Over a large area selective tree
thinning is thus spread along the length of the erosion area.
The cut branches of the thorn trees are then fed through a PTO-driven (or
motorised) chip mulch machine. The chip mulch machine can be positioned at
each core rehabilitation site and enough mulch produced, at each site, to
adequately cover the newly shaped area.
It is important to appreciate that a great deal of mulch will be required and that this
requirement may significantly reduce the ready supply of some areas. It is,
however, also important to understand that the temporary loss of thorn trees and
other bigger shrubs is extremely valuable for the rehabilitation work and also that
the cut trees will resprout and with time, replace what was removed.
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