Patch creation by fossorial rodents: a key process in the revegetation of phytotoxic arid soils

The recolonization by plants of overburden dumps created more than 20 years ago by opencast diamond-mining activities on the west coast of South Africa is very slow to non-existent. Only on dumps where the fossorial rodentParotomys brantsii has created burrow networks has some natural revegetation occurred. We tested the hypothesis that this plant colonization is facilitated by rodent burrowing activities which create soil patches containing organic matter and soil microbial propagules. Nearest-neighbour analysis of burrow–plant and random point–plant pairs showed that rodent burrows are associated with the occurrence of plants. There was a significantly higher pH, significantly lower electrical conductivity, and a five-fold increase in microbial activity between control and burrow mound soils on dumps. These fossorial rodents create small patches (c. 0•5×0•5 m) of increased ‘fertility’ that encourage plant colonization in an otherwise edaphically hostile environment.