Factors influencing colonisation processes in two contrasting mine sites in the Namib Desert

I investigated vegetation recovery in a uranium mine in the central Namib and a diamond mine in the southern Namib to better understand natural recovery processes in arid areas. Environmental variables influencing colonisation processes were investigated using multivariate analyses to examine the relative importance of environmental variables on vegetation recovery at the two mines. Disturbance level was the most important variable influencing colonisation processes in the central Namib whereas distance to seed source was the most important in the southern Namib. At both mines, the proximity of a species pool to the disturbed areas (reference species pool) was more important than the pool of available species in the broader ecological community in which the mines were located (ecological species pool). The study indicates that merely relying on spontaneous, natural recovery is insufficient in the Namib if (1) pre-mining conditions are the restoration goal and (2) presently undisturbed or well recovered areas in the mine cannot be preserved as a suitable seed sources in the southern Namib. Appropriate completion criteria need to be developed that consider local conditions in order to ensure that restoration of mines in arid areas is realistic.