CSIRO Waite Campus Seminar: Assoc. Prof. Stuart Grandy
Apr 26, 10:30 am
The following Seminar will be taking place on Wednesday 26th April in the CSIRO Building 1 Seminar Room, Gate 4 Waite Road, Urrbrae. Morning tea from 10:30am with presentation at 11am.
Assoc. Prof. Stuart Grandy, Professor of Hydrology
Roland H. O’Neil Associate Professor of Soil Biogeochemistry and Fertility
Department of Natural Resources and the Environment | University of New Hampshire
Scaling soil organic matter dynamics with microbial physiology
Soil organic matter (SOM) regulates multiple ecosystem processes, including the exchange of trace gases and primary productivity. Recently, there has been vigorous debate over the role that microbial products play in forming stable soil organic matter, with increasing analytical evidence using isotopes, molecular chemistry, and microscopy all showing that SOM possesses a strong microbial signature. However, scaling these observations – typically made at the molecular to micron or nano scales – to ecosystems or larger scales remains challenging. Here we show that microbial physiological processes such as growth efficiency and growth rate regulate the accumulation of microbial products. These processes are tied to microbial community structure and are strongly regulated by ecosystem disturbance. In our experiments with model artificial soils accruing SOM and field soils with varying soil C concentrations, the accumulation of SOM is closely related to microbial physiology. Further, the rate and efficiency that isotopically labelled C is converted to soil C depends strongly on microbial physiological characteristics and community structure. Given the sensitivity of microbial physiological characteristics to disturbance, these physiological traits can help explain ecosystem-scale SOM responses to environmental changes.
Variation in microbial physiology can also be directly incorporated into models, allowing us to scale microbial processes that regulate SOM formation to regional and global scales. Here we demonstrate the incorporation of microbial processes into MIMICS, the MIcrobial MIneral Carbon Stabilization model. Moving from ecosystem to larger scales, we demonstrate that MIMICS, a microbial-explicit model with output strongly dependent on microbial physiology, is able to predict large-scale soil C dynamics as well as or better than conventional models. Microbial physiology, which varies among microbial groups and is highly sensitive disturbance, can be used to scale from the smallest processes regulating SOM formation to global C cycling.
ABOUT THE SPEAKER
Stuart is the Roland H. O’Neil Associate Professor of Soil Biogeochemistry and Fertility at the University of New Hampshire. His research examines how soil organisms interact with their environment to regulate ecosystem processes such as nutrient cycling, organic matter turnover, trace gas emissions, and productivity. This research encompasses multiple spatial scales and lies at the interface of soil ecology, biogeochemistry, and ecosystem science. His lab uses a range of fundamental laboratory methods, which include molecular chemical and microbiological approaches, and always has an eye towards applying results to improve ecosystem processes and management. More can be found at the Grandy lab website, www.unh.edu/grandylab.
Enquiries to Jessica Ernakovich (Jessica.Ernakovich@csiro.au)