LONG-TERM IMPACTS OF BURIED ANIMAL CARCASSES ON SOIL BIOGEOCHEMISTRY IN THE NORTHERN GREAT PLAINS

Decomposing animals provide both short- and long-term impacts to soil biogeochemistry. In surface settings, most physical and chemical parameters return towards background conditions after months, with some longer-term indicators of decomposition, notably stable nitrogen isotopes, persisting for years. In burial settings, trends are less-resolved, particularly in arid regions such as western South Dakota. Approximately 10 beaver carcasses were placed on the surface of a western SD prairie, buried to ~50 cm depth in 2005, and left undisturbed until Fall 2021. Soils were collected along transects at the surface and at depth, were expected to retain a signature of decomposition. A range of physicochemical parameters including pH, conductivity, dissolved organic carbon, microbial respiration rates, soil major and trace elements, and stable nitrogen and carbon isotopes were examined. Conductivity in soil surrounding carcasses was significantly elevated compared to control soils at depth and at the surface, and pH was significantly lower than controls at depth. Water soluble metal concentrations varied between soils associated with animal decomposition at depth and controls at both depth and surface. In general, decomposition associated soils had higher concentrations of Na, Ca, Mg, Ni, and Sr, and lower concentrations of Al, K, Ti, Mn, Fe, Ba, and Mo relative to control soils. Blowfly casings were still adjacent to and surrounding the carcasses 15 years post-placement, demonstrating the potential for both physical and chemical markers of decomposition to persist in shallow soils. Shallow burial in terrestrial settings may facilitate bone preservation over time despite continued and protracted biogeochemical activity.