Transient hypoxia drives soil microbial community dynamics and biogeochemistry during human decomposition

Area of Science:

• Forensic science
• Soil science
• Microbiology

Background:

• Human decomposition creates localized soil microbial hotspots.
• Longer-term impacts (beyond months) on decomposer microbial communities and their link to biogeochemistry are poorly understood.

Purpose of the Study:

• To investigate the year-long impacts of human decomposition on soil microbial communities.
• To connect microbial community structure and abundance with soil physicochemistry and biogeochemistry.
• To identify key drivers of microbial community change during decomposition.

Main Methods:

• Conducted year-long human decomposition trials, starting in spring and winter.
• Integrated bacterial and fungal community structure with soil physicochemistry and biogeochemistry.
• Analyzed microbial respiration, soil oxygen, pH, and nitrogen transformations.

Main Results:

• Decomposition caused soil acidification, increased microbial respiration, and reduced soil oxygen.
• Soil oxygen was the primary driver of microbial succession and nitrogen cycling.
• Fungal diversity and abundance correlated with soil pH.
• Facultative anaerobic bacteria (Firmicutes) and fungi (Saccharomycetes) increased with reduced oxygen.
• Spring decomposition effects were more pronounced than winter effects, even when accounting for temperature.
• Soil parameters and microbial communities remained altered after one year.

Conclusions:

• Human decomposition has significant, lasting impacts on soil microbial communities and biogeochemistry.
• Soil oxygen dynamics and pH are critical factors influencing microbial responses to decomposition.
• Decomposition alters soil ecosystems for extended periods, affecting microbial structure and function.