Illuminating soil biogeochemical responses to press and pulse disturbances in a coastal ecosystem
EMSL Project ID
60036
Abstract
Coastal ecosystems are undergoing dramatic transitions as sea level rise accelerates and precipitation and storm regimes change. Depending upon the intensity and duration of seawater exposure, coastal ecosystems are subjected to both press and pulse disturbances and often exhibit high sensitivity and variable responses to shifts in inundation and salt exposure, challenging our ability to accurately predict carbon (C) and nutrient dynamics at local and global scales. To disentangle interacting factors and processes that drive emergent ecosystem responses to different disturbance scenarios in coastal ecosystems, we propose utilizing EMSL and JGI resources characterize changes in soil organic matter (OM) chemistry and microbial function under the individual and combined influences of increased water availability and salinity. Through comprehensive assessment of OM chemistry and microbial community composition and metabolic pathways, we will (1) attain molecular-level understandings of soil microbial metabolism and associated C transformations that underpin ecosystem greenhouse gas (GHG) fluxes, and (2) refine the functional relationships among microbial metabolism, substrate variability and environmental drivers that are underrepresented in current biogeochemical models. We will do this by leveraging two existing manipulative field experiments that evaluate ecosystem dynamics from mesocosm to ecosystem scales: 1) Our multi-year soil mesocosm transplant experiment relies on a unique reciprocal design between sites varying in inundation and seawater exposure regimes. This experiment addresses the response of coastal forest C cycling to the combined effects of inundation and salinity, applied as a press disturbance. 2) In our newly launched field manipulation experiment, we explore coastal forest responses to pulse disturbance and separate the effects of inundation and salinity from hydrologic legacy at the ecosystem scale. We posit that the relationships between environmental drivers (e.g. inundation and salinity) and surface GHG fluxes depend on both the prior conditions shaping microbial community structure and new conditions that alter microbial activities. By characterizing microbial community composition and metabolic pathways, as well as soil OM chemistry, we will be able to develop mechanistic linkages between environmental drivers and emergent ecosystem level C (GHG fluxes) and nutrient dynamics. The proposed measurements are critical for constraining the biogeochemical reaction networks currently implemented in biogeochemical and reactive transport models.
Project Details
Project type
FICUS Research
Start Date
2021-10-01
End Date
2023-10-01
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members