Biomolecular linkages between detrital inputs and soil organic matter decomposition in temperate forests
EMSL Project ID
50417
Abstract
The DIRT project is a multi-decade experiment that manipulates litter inputs to large plots in a western coniferous forest by increasing needle litter or woody debris inputs, eliminating aboveground or belowground inputs, and eliminating both above- and belowground inputs. This experiment is designed to address such questions as: what controls the long-term storage of C in soil organic matter (SOM)? Does the chemical quality of detrital inputs affect SOM stability? What chemical and physical fractions of SOM are the most stable C pools? We propose to use EMSL’s ultra-high-resolution mass spectrometry to investigate and probe for changes in the molecular chemistry of soil organic matter (SOM) following twenty years of detrital input manipulations in these plots at one site in the H.J. Andrews Forest, Oregon. We request proof-of-principle results before expanding our analyses to the larger suite of DIRT plots, some of which have been maintained for almost 30 years.
Our proposed research would provide a comprehensive, molecular-level understanding of the effects of changing detrital quality and quantity on soil organic matter stabilization, C balance, and nutrient cycling and availability. The Department of Energy’s Office of Biological and Environmental Research (BER) is actively seeking research that will develop a molecular-scale understanding of the processes controlling ecosystem C cycling that can inform land surface models. Understanding the processes and mechanisms that control the flux and stabilization of soil C is thus vital not only to ecosystem management, but also to the accurate prediction of terrestrial carbon feedbacks to climate change. The multi-decade, experimental nature of DIRT is unique to environmental science and is uniquely suited to explore the role of plant detrital quality and quantity in determining SOM stabilization and accumulation, which is a significant unknown factor in current models of C sequestration in ecosystems.
For this rapid access proposal, we propose to probe the molecular chemistry organic matter in bulk soils from six treatment plots and at three or more depths in the soil profile from the Andrews Forest; these data will serve as the basis for a larger proposal that will include the other sites. We will use EMSL’s 12 T FTICR-MS and the soil extraction protocol developed by Tfaily et al. (2017). At EMSL, two solvents (water, and chloroform) with different polarities will be used to sequentially extract a representative fraction of organic matter from belowground soils according to protocol 1 in Tfaily et al. (2017). A 12 Tesla Bruker SolariX FTICR spectrometer will be used to collect high resolution mass spectra and identify chemical formulas of individual SOM compounds in the extracts. A standard Bruker ESI source will be used to generate negatively charged molecular ions Unique biochemical compounds and abundances will be determined from the resulting data using established compound identification algorithms (Formularity software (Toli? et al., 2017)). Additionally, to determine decomposition pathways, we will use mass-mass differences between mass spectral peaks to identify parallel metabolic reactions under the assumption that certain mass differences corresponding to specific chemical changes are related by the equivalent metabolic transformation.
Project Details
Project type
Limited Scope
Start Date
2018-09-02
End Date
2018-11-02
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members