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 Afric a is very slow to non-existent. Only on dumps where the fossorial rodent Pa rotomys brantsii has created burrow networks has some natural revegetation occurred. We tested the hypothesis that this plant colonization is facilita ted by rodent burrowing activities which create soil patches containing org anic matter and soil microbial propagules. Nearest-neighbour analysis of bu rrow-plant and random point-plant pairs showed that rodent burrows are asso ciated with the occurrence of plants. There was a significantly higher pH, significantly lower electrical conductivity, and a five-fold increase in mi crobial activity between control and burrow mound soils on dumps. These fos sorial rodents create small patches (c. 0.5 x 0.5 m) of increased 'fertilit y' that encourage plant colonization in an otherwise edaphically hostile en vironment. (C) 1999 Academic Press.