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Dynamic soil nutrient and moisture changes under decomposing vertebrate carcasses

- Quaggiotto, Maria, Evans, Maldwyn, Higgins, Andrew, Strong, Craig, Barton, Philip

  • Authors: Quaggiotto, Maria , Evans, Maldwyn , Higgins, Andrew , Strong, Craig , Barton, Philip
  • Date: 2019
  • Type: Text , Journal article
  • Relation: Biogeochemistry Vol. 146, no. 1 (2019), p. 71-82
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  • Description: 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. © 2019, Springer Nature Switzerland AG.

Nutrient and moisture transfer to insect consumers and soil during vertebrate decomposition

- Barton, Philip, Strong, Craig, Evans, Maldwyn, Higgins, Andrew, Quaggiotto, Maria

  • Authors: Barton, Philip , Strong, Craig , Evans, Maldwyn , Higgins, Andrew , Quaggiotto, Maria
  • Date: 2019
  • Type: Text , Journal article
  • Relation: Food Webs Vol. 18, no. (2019), p.
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  • Description: Decomposition of organic matter leads to the redistribution of nutrients to organisms and the environment. Yet knowledge of this process has focused largely on plant-derived organic matter, with little known about relative quantities of nutrients and moisture transferred from decomposing animal remains to insect consumers and soil. We used a replicated and spatially blocked experiment to quantify the moisture, carbon, nitrogen, and phosphorous content of rabbit carcasses, maggot consumers, and soil over 20 days of decomposition. We found that maggot biomass reached 22% of the fresh rabbit carcass, or 39% of the consumable soft tissues. Maggots were comprised of 68% moisture, and their dry mass was comprised of 25% carbon, 4.9% nitrogen, and 0.8% phosphorous. Soils accumulated approximately 12.9% of the total carcass moisture, but only 0.7% of the carcass dry mass. The largest quantity of carcass mass loss was attributable to evaporation of moisture to the atmosphere (45%). Approximately 9% of the initial carcass mass was left as unconsumed remains. Our study provides estimates of the quantities of nutrients moving from vertebrate carcasses to insect consumers and soil. This knowledge is critical to scaling up the effects of carcasses and to developing our understanding of their role in biogeochemical cycling in ecosystems. © 2018 Elsevier Inc.

Soil chemical markers distinguishing human and pig decomposition islands : a preliminary study

- Barton, Philip, Reboldi, Anna, Dawson, Blake, Ueland, Maiken, Strong, Craig, Wallman, James

  • Authors: Barton, Philip , Reboldi, Anna , Dawson, Blake , Ueland, Maiken , Strong, Craig , Wallman, James
  • Date: 2020
  • Type: Text , Journal article
  • Relation: Forensic Science, Medicine, and Pathology Vol. 16, no. 4 (2020), p. 605-612
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  • Description: The decomposition of vertebrate cadavers on the soil surface produces nutrient-rich fluids that enter the soil profile, leaving clear evidence of the presence of a cadaver decomposition island. Few studies, however, have described soil physicochemistry under human cadavers, or compared the soil between human and non-human animal models. In this study, we sampled soil to 5 cm depth at distances of 0 cm and 30 cm from cadavers, as well as from control sites 90 cm distant, from five human and three pig cadavers at the Australian Facility for Taphonomic Experimental Research (AFTER). We found that soil moisture, electrical conductivity, nitrate, ammonium, and total phosphorus were higher in soil directly under cadavers (0 cm), with very limited lateral spread beyond 30 cm. These patterns lasted up to 700 days, indicating that key soil nutrients might be useful markers of the location of the decomposition island for up to 2 years. Soil phosphorus was always higher under pigs than humans, suggesting a possible difference in the decomposition and soil processes under these two cadaver types. Our preliminary study highlights the need for further experimental and replicated research to quantify variability in soil properties, and to identify when non-human animals are suitable analogues. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.
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