Dynamic soil nutrient and moisture changes under decomposing vertebrate carcasses

Abstract

The decomposition of animal carcasses contributes to nutrient recycling in ecosystems worldwide, including by delivering nutrients to soil. Although several studies have characterised changes in soil chemistry occurring under carcasses, many ecological studies have occurred over extended post-mortem intervals and fine-scale temporal changes in physicochemical conditions are poorly understood. We examined changes in a suite of soil physicochemical properties occurring under decomposing rabbit carcasses during summer in a grassland ecosystem. We found that carcasses lost over 90% of their starting mass and reached dry decay and skeletonization after 20 days of decomposition. Carcass temperatures were up to 15 °C higher than ambient temperatures during the active decay stage (days 3 and 5) of decomposition. Soil moisture also increased by day 4, and this was matched with a simultaneous increase in total nitrogen and ammonium, as well increases in pH and electrical conductivity. Whereas these measures remained relatively stable as decay progressed, we found total phosphorus and phosphate continued to increase to day 20. The contrasting dynamics of N and P reflect the initial nutrient and fluid input during the rapid decay of soft tissues and intense activity of fly larvae, and the subsequent dry decay and exposure of skeletal components. Our study provides new information about the fine-scale timing of nutrient inputs and moisture and temperature changes occurring at the carcass/soil interface.