Soil organic carbon (SOC) plays a crucial role in the terrestrial carbon cycle. Soil microbial communities are the primary agents responsible for SOC cycling, but the exact drivers of microbial dynamics at the macroscale (regional to biome) are not fully understood. An accurate representation of SOC cycling at the macroscale is crucial to understand the role of soils in climate change and to inform soil management. One potential limiting factor for soil microbial activity is energy availability. Energy limitation could constrain microbial growth in soils and consequently limit SOC turnover. However, the precise relationships between energy limitation and microbial processes in soils remain unclear.
The goal of this project is to explore how energy availability influences soil microbial growth and carbon use efficiency at the macroscale. Specifically, we will conduct incubation experiments to investigate the bioenergetics of microbial communities in aerated mineral soils along a gradient of temperate grasslands. We will characterize the energetic properties of microbially-accessible soil organic matter using advanced techniques, including Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and microcalorimetry. We will then explore whether this information can help to improve our understanding of previously published microbial dynamics (Wasner et al., 2024).
The objectives of this work are to:
- quantify microbially available energy across diverse grassland soils,
- assess the biogeochemical drivers of energy availability at the macroscale and
- understand if and how variations of microbially available energy affect microbial SOC turnover.
We expect that this research will reveal links between the biogeochemical properties of soils, energetic properties of SOC and microbial dynamics. Understanding these links will provide deeper insights into microbial dynamics and SOC cycling at the macroscale, which will ultimately help to better represent soil organic carbon dynamics.
People: Daniel Wasner