Biopedturbation by mammals in deserts: a review

Disturbance-caused patchiness is important for development and maintenance of spatial and temporal heterogeneity in ecosystems. Mammals are important agents of biopedturbation (soil disturbance by organisms) which is a major source of patchiness in arid ecosystems. The contribution of soil disturbance by mammals to heterogeneity is a function of the size and longevity of the soil disturbance. Foraging pits produced by a variety of mammals are relatively short-lived features that trap plant litter and seeds that are rapidly buried. These form nutrient-rich germination sites. High water infiltration rates, a low bulk density rooting environment, and frequently increased soil nutrient content (especially mounds of central-place foragers and larder-hoarders) characterize warren complexes. Productivity tends to be higher on these mounds and the vegetation tends to differ in composition and richness from the surrounding areas. Soil ejected from fossorial mammal burrow systems is generally of low bulk density, erodes readily, and varies greatly with respect to concentration of nutrients and organic matter depending upon the species and landscape in which the species lives. The variability in soil properties of fossorial burrow system ejecta mounds precludes generalizations about the effects of these disturbances on vegetation. Long-lived features such as Mima-like mounds and heuweltjies are nutrient-rich features that support high productivity and a distinct floral assemblage. There is a significant relationship between longevity of mammal soil disturbance and size of the disturbance: longevity in years = 9.33 Area(0.735). The data suggest that pedturbation by mammals can be an important force in pedogenesis, in structuring landscapes, and in maintaining heterogeneity in ecosystems. Data on mammalian pedturbation is based on scattered autecological studies. There is a need for long-term studies that focus on biopedturbation (soil disturbance by invertebrates and vertebrates) as a process at scales from the patch to the landscape. (C) 1999 Academic Press.