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Organized Oral Session

Session: : Soil Microbiota and Post-fire Community Recovery

OOS 41-6 - Linking molecular signatures of fire history with microbial function; Leveraging MONet

Wednesday, August 9, 2023
11:15 AM – 11:30 AM PDT
Location: 256
Soil organic matter (SOM) is a critical part of the global carbon (C) cycle, with belowground ecosystems containing more C than stored in terrestrial vegetation and the atmosphere combined. SOM decomposition is regulated by a series of complex and om factors including soil structure, moisture distribution, temperature, pH, nutrient status, and disturbance events. Despite the importance of SOM in the global C cycle, the drivers of SOM decomposition from molecular to continental scales are not well understood. Advances in molecular technologies have the power to elucidate these processes, yet there is no widespread standardized implementation of molecular techniques. To understand the drivers of global C cycling, we developed a crowdsourced soil core research program for analyzing molecular and microstructural data that describe SOM chemistry, soil microbiology, and soil structure. To provide such data, the Environmental Molecular Sciences Laboratory (EMSL) is developing a regional- and continental United States (CONUS)-scale database of high-resolution molecular and microstructural soil data. EMSL’s Molecular Observation Network (MONet) encompasses an open network of scientists contributing data to a searchable FAIR database and growing and EMSL community of users. Using data from MONet, we link changes in the molecular signatures with changes in the microbial function and composition. Using MONet’s standardized sampling protocols, soil cores were collected by participants and returned to EMSL for analysis. At each site, two 30 cm soil cores and four 10 cm soil cores to capture surface heterogeneity were collected. One of the 30 cm cores is used to measure the soil biological and chemical properties, while the remaining 30 cm core is used to measure the soil physical properties. Soil cores are depth segmented into 10 cm sections and homogenized prior to biological and chemical analysis. Within the three ecosystems, we observed decreases in soil respiration, microbial biomass, and potential enzyme activity in soils with recent fire history. We observed differences between the microbial community between the surface soils of burned and unburned soils. Additionally, we observed shifts in SOM composition, with SOM composition becoming more oxidized and increases in the nominal oxidation state of carbon (NOSC) with fire exposure as well as separations in SOM composition between unburned and burned comparisons. While more samples are needed to link meta-genomes with transformations in SOM, this standardized protocol and analyses has allowed us to link meta-genomes with SOM composition response to fire across multiple ecosystems.