Abstract - Effects of Prairie Dogs on Mound Soils

Carlson, Daniel C. 1986. Effects of Prairie Dogs on Mound Soils. M.S. Thesis. South Dakota State University, Yankton, SD. 116+ p.

Abstract

Biological pedoturbation is a process of soil formation which has not been studied extensively. Pedoturbation is the physical and/or biological mixing of soil material which tends to homogenize soil color and reduce soil morphology differences in the soil solum. Pedoturbation is often a sub-surface or scarcly-noticeble soil surface activity, yet many studies dealing with soil mixing are based on surface observations of displaced soil without considering soil profile changes below the surface in determining the volume of soil disturbed by mixing.

Black-tailed prairie dogs (Cynomys ludovicianus) are burrowing rodents that alter soil development on gently-sloping, shortgrass areas of the Great Plains. The construction of "mounds" of soil is characteristic of this species, the result of burrowing into soil surfaces, subsoil tunneling, and concurrent soil excavation. The amount of excavated subsoil redeposited on the original soil surface increases with time as burrowing activity alters subsoil development and as new burrows are constructed in the same tunnel system.

Soils which are part of or underneath mound surface soils are chemically and physically different compared to soil derived from the same parent material in the absence of pedoturbation. The mound soil is generally lighter in color, coarser-textured, higher in pH, lower in organic matter, variable in nitrogen content, and marked as a site of phosphorus accumulation by the addition of fecal, carcass, and plant residue wastes over time. Phosphorus accumulation in mound soil due to its relative chemical immobility would depend on the length of time a mound has been used by prairie dogs.

The ojectives of this study were:

1. To examine soil development within selected prairie dog mounds compared to adjacent, non-mixed soil profiles.
2. To chemically analyze mound and adjacent non-mound soils in determining laboratory analyses which most consistently measure the length of time a mound has been used.
3. To estimate relative ages of studied mounds from mound surface area, underlying subsoil mixing, surface soil color and pH distribution, and from accumulation of total phosphorus in mound soils.