Effects of multispecies clumping on survival of three succulent plant species translocated onto mine spoil in the Succulent Karoo Desert, South Africa

Salvaging from premining areas and translocation of succulent plants has been investigated for the revegetation of gypsiferous mine spoil in an arid region of South Africa. Given that facilitation effects are thought to outweigh competition effects in harsh environments, we hypothesized that the survival of translocated succulents would be higher when planted in multispecies clumps than alone and that the growth rate (measured as stem extension) and fruit-set would be greater for plants in clumps than for those planted alone. Two leaf-succulent species (Aridaria noctiflora ssp. noctiflora and Drosanthemum deciduum) and one stem-succulent species (Psilocaulon dinteri) were salvaged from the area destined for mining and translocated onto the mine spoil. These plants were planted either in a multispecies clump of the three species together or alone. One year after translocation, 67% of the plants survived. It was also found that the succulents used in these experiments survived in higher numbers when planted alone. Due to the similar root morphology of D. deciduum and P. dinteri, they competed for resources instead of facilitating each other's establishment. The results were variable for each of the species used, and neither growth nor seed-set was improved by clumping. These findings would also possibly vary from year to year with different abiotic conditions.