FEATURE
Although plant and species densities were similar on the deep ( Site 1 ) and shallow ( Site 2 ) soil , plants appeared to perform better on deeper soils and produce more cover , biomass and seed than they did on shallow soils ( compare Figures 2 and 4 ).
As evidenced by trap camera photographs and dung observations , plants established in hollows at both sites attracted herbivores and granivores . While brush-packing protected plants from excessive herbivory , the herbivores visitors contributed to diversity and productivity through seeds and nutrients in the dung they deposited on the rehabilitation sites ( Figure 5 ).
Lessons learned
Figure 4 . Development of plants in brush-packed hollows in Site 1 over five years from August 2016 until September 2021 .
Figure 5 . Development of plants in brush-packed hollows in Site 1 over five years from August 2016 until September 2021 . ( A ) Two Steenbok ( Raphicerus campestris ) grazing plants in a hollow at Site 1 , ( B ) Scrub Hare ( Lepus saxatilis ) dung in a hollow at Site 1 .
species in 2021 . At site 2 the patterns were similar with 18 % of plants and 22 % species originating from the seed mix in 2018 , with the representation of seed mix species increasing to 24 % of plants and 31 % of species in 2021 . The most abundant species on the stony ground were Cenchrus ciliaris and Fingerhuthia africana ( in the mix ) and Enneapogon scaber ( self dispersed ). On deep silty soil the most abundant species were the alien invasive shrub Atriplex lindleyi ( self-dispersed ) succulents Augea capensis ( in the mix ) and Mesembryanthemum tetragonum ( self-dispersed ), and the grasses Fingerhuthia africana ( in the mix ) and Ennepogon scaber ( selfdispersed ).
We have shown that in very arid areas such as Prince Albert , the concentration of the available water appears to be the most successful means of achieving plant establishment and survival on bare ground , even during drought . This can be achieved through the creation of small , shallow hollows , either by hand digging or use of a modified plough known as a “ hap ploeg ” ( Coetzee & Stroebel 2015 ). The hollows are aligned to trap runoff water and should have a rim on the downslope side so as to retain some of the water they capture . The optimal depth for hollows will vary with soil texture and sandy soils drain fast and the hollows rapidly dry out , whereas on clay soils the hollows retain water long enough to drown seedlings ( Milton & Dean 2021 ; Genis 2021 ). Ideally , the hollows and surrounding soil should stay moist for at least a week after rain to facilitate germination and seedling establishment ( Figure 6 ). Mulching of hollow helps retain moisture and also prevents fine-textured soils from peeling , cracking and lifting seedlings out of the ground . Covering hollows with thorn bush protects seeds from medium to large herbivores for a few years until they are established .
Although brush-packing without hollows can stabilize soil and promote germination in some areas ( Saayman & Botha 2010 ), this treatment was not successful on our study sites . Possible reasons for lack of success may be the failure of brush-packed areas to retain rainwater , exclusion of light in denselypacked areas , and possibly also diversion of tumble-seeds away from the brush-packed areas .
The addition of seeds appropriate for the site conditions is justified when seed availability in the surrounding landscape is limited by grazing , drought or
13 Grassroots Vol 22 No 1 March 2022