Beyond the rhizosphere: Microbial functional traits through the whole soil profile and their response to warming.
EMSL Project ID
50964
Abstract
The pathways of carbon transport and loss through and from soils--soil organic matter (SOM) depolymerization to dissolved organic carbon and mineralization to carbon dioxide (CO2)--are fundamentally driven by microbial activity, which is strongly regulated by environmental conditions. Soil conditions such as physical-chemical properties, nutrient inputs and organic matter chemistry change markedly with soil depth, due in part to a decreasing influence of plant inputs and changes in mineral-organic interactions. Such factors may select for microbial communities with distinct metabolic, physiological and cellular properties (i.e. microbial traits) that will likely constrain the trajectory and magnitude of the respiration response to warming through the soil profile.
As part of LBNL TES SFA, we established a novel whole-soil long-term warming experiment at the University of California (UC) Blodgett Forest Research Station (Sierra Nevada) in 2014, where we are studying the role of biogeochemical, microbial and geochemical process interactions in SOM decomposition and stabilization. As part of this SFA, we are investigating microbial responses and feedbacks to warming through the whole soil profile. We have shown that warming the whole soil profile (+ degrees C) for two years increased annual soil respiration by 34-37%, and that more than 40% of this increase came from below 15 cm depth (Hick Pries et al. 2017). Analyses of microbial dynamics, enzyme activity and carbon use efficiency strongly suggest that microbial response through the soil profile is not uniform, and are suggestive of phasing, whereby microbiomes of deeper soil horizons change more slowly in response to warming than surface horizons. We hypothesize that differences in microbial trait distributions, substrate energetics, substrate stoichiometry and mineral surface reactivity through the soil profile contribute to a phased response to warming.
Our specific aims in this proposal are:
- Assess the distribution of genome-derived functional traits through the soil profile and their relationships with soil properties that co-vary with depth and with changes in environmental conditions, namely warming.
- Investigate active metabolic, physiological and cellular pathways/mechanisms involved in SOM decomposition, nutrient acquisition and adaptation to warming and associated environmental changes.
- Characterize SOM composition, quantify the distribution of carbon chemical classes with depth as a function of temperature, and investigate how these contribute to selection of microbiomes with distinct functional traits and activities.
Our overall goal is to identify generalizable interaction mechanisms between microbial traits, soil organic matter properties and environmental conditions underlying SOM decomposition, to improve the model representation of soil microbial-biogeochemical feedbacks to warming.
Project Details
Project type
FICUS Research
Start Date
2019-10-01
End Date
2022-06-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members