Hydrologic imprinting across terrestrial-aquatic gradients: unraveling the spectrum of ecosystem responses to freshwater limitation and salt exposure
EMSL Project ID
50234
Abstract
The availability of freshwater exerts a direct influence on the growth and health of plants both in terrestrial and aquatic ecosystems (e.g., wetlands). Upland soils can experience accumulation of salts during times of drought, while lowland systems near the coast can be additionally affected by tidal inundation dynamics over short time scales and salt-intrusion over longer periods. The proposed project will examine how coupled plant-soil-microbe interactions, and related biogeochemical transformations and fluxes, respond to rapid changes when different past hydrologic regimes have been experienced. For example, are microbes and plants found in the soils and sediments of tidally-influenced sectors of a particular ecosystem more readily adaptable to perturbations (e.g., increased salt intrusion) compared to upstream communities? Likewise, will increasing flood/drought cycles inhibit the ability for ecosystems to resist and recover from extreme events and what does this mean with respect to biogeochemical fluxes? A series of field measurements, microcosm experiments, and modeling exercises will be performed in a small coastal watershed, starting near the river mouth, which receives tidal intrusion of saltwater into the river channel and adjacent landscape, and ending upstream of any tidal or salt influence. We have established transects spanning the "terrestrial-aquatic interface" (e.g., soils/sediments, porewater, and surface waters from the river channel to the hillslope) at 3 locations along the river continuum (i.e., high salt exposure, medium salt exposure, and no exposure to tides/salt). Across each transect we will measure a suite of biogeochemical parameters and fluxes and examine similarities/differences in soil microbial gene expression, microbial metabolites, and organic matter composition. Soil cores will be exposed to various salinity treatments in the lab to relate biogeochemical responses to their historic range of fresh and saltwater exposure. Information from field and lab measurements will be incorporated into a reach-scale reactive transport model to determine the key ecosystem processes and responses driving biogeochemical fluxes. We request EMSL resources for ultra-high resolution organic matter characterization and metabolite profiling, which will unlock our ability to evaluate how soil microbial communities respond to shifts in salt exposure and alter biogeochemical fluxes.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2018-10-01
End Date
2021-03-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Sengupta A., J.L. Indivero, C.M. Gunn, M.M. Tfaily, R.K. Chu, J.G. Toyoda, and V.L. Bailey, et al. 2019. "Spatial gradients in the characteristics of soil-carbon fractions are associated with abiotic features but not microbial communities." Biogeosciences 16, no. 19:3911-3928. PNNL-SA-143361. doi:10.5194/bg-16-3911-2019
Sengupta, A., Stegen, J., Bond-Lamberty, B., Rivas-Ubach, A., Zheng, J., Handakumbura, P., Norris, C., Peterson, M.J., Yabusaki, S., Bailey, V., Ward, N.D. (2021) Antecedent conditions determine the biogeochemical response of coastal soils to seawater exposure. Soil Biology & Biochemistry. 108104. https://doi.org/10.1016/j.soilbio.2020.108104