Author
 |
WHITFORD, WALTER - NEW MEXICO STATE UNIV |
|
KAY, FENTON - SWCA INC-ENV CONSULTANT |
|
Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/1/1999 Publication Date: N/A Citation: Whitford, W.G., Kay, F.R. Biopedturbation by mammals in deserts: A review. Journal of Arid Environments. 1999. v. 41(2). p. 203-230. Interpretive Summary: Biopedturbation, or animal-caused soil disturbance, has been shown to be an important process in maintaining ecosystem heterogeneity or patchiness. In arid lands, mammals are an important source of biopedturbation. The contribution of biopedturbation to landscape heterogeneity is a function of the size and longevity soil disturbance. There are several types of mammal-caused soil disturbances. Foraging pits dug by small mammals are short-lived features that trap litter and seeds often forming nutrient-rich germination sites. Burrows systems dug by rodents may persist on the landscape for several decades and can become hot spots that support relatively rare or exotic plant species. Rodent burrows have also been associated with an increased depth of water penetration into the soil and a higher soil nutrient content. Soil ejecta piles from rodent burrows and pits are often markedly different in chemistry and texture from the surrounding soil. In addition, several species of desert animals depend on rodent burrows for shade and shelter. This review suggests that soil disturbance by mammals can be an important force in soil development, structuring landscapes, and maintaining ecosystem heterogeneity in arid environments. In order to better understand how biopedturbation contributes to landscape function, long-term studies of all biopedturbation types are necessary. Technical Abstract: 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 live. 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 to the 0.735 power. The data suggest that pedturbation by mammals can be an important force in pedogenesis, in structuring landscapes, and in maintaining heterogeneity inecosystems. 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. |
