期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 802, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.149715
关键词
Wetland; Carbon dioxide; Soil respiration; Aquatic-terrestrial interface; Blue carbon; Hysteresis
资金
- National Science Foundation [1652594]
- Delaware Environmental Fellowship
- NSF Graduate Research Fellowship [1247394]
- Direct For Biological Sciences
- Division Of Environmental Biology [1652594] Funding Source: National Science Foundation
This study investigated the patterns and drivers of soil CO2 efflux in temperate tidal marshes, finding that soil CO2 efflux is influenced by factors such as air temperature. There were large discrepancies between manual and automated soil CO2 efflux measurements. New technical approaches are needed to accurately estimate the carbon balance in wetland ecosystems.
Tidal marshes store large amounts of carbon; however, little is known about the patterns, magnitudes, and biophysical drivers that regulate CO2 efflux from these ecosystems. Due to harsh environmental conditions (e.g., flooding), it is difficult to measure continuous soil CO2 efflux in tidal marshes. These data are necessary to inform empirical and process-based models and to better quantify carbon budgets. We performed automated (30 min) and manual (bi-monthly) soil CO2 efflux measurements, for -20 months, at two sites in a temperate tidal marsh: tall Spartina (TS; dominated by S. cynosuroides) and short Spartina (SS; dominated by S. alterniflora). These measurements were coupled with water quality, canopy spectral reflectance, and meteorological measurements. There were no consistent diel patterns of soil CO2 efflux, suggesting a decoupling of soil CO2 efflux with diel variations in temperature and tides (i.e., water level) showing a hysteresis effect. Mean soil CO2 efflux was significantly higher at SS (2.15 +/- 1.60 mu mol CO2 m(-2) s(-1)) than at TS (0.55 +/- 0.80 mu mol CO2 m(-2) s(-1)), highlighting distinct biogeochemical spatial variability. At the annual scale, air temperature explained >50% of the variability in soil CO2 efflux at both sites; and water level and salinity were secondary drivers of soil CO2 efflux at SS and TS, respectively. Annual soil CO2 efflux varied from 287-876 to 153-211 g C m(-2) y(-1) at SS and TS, respectively, but manual measurements underestimated the annual flux by <67% at SS and <23% at TS. These results suggest that measuring and modeling diel soil CO2 efflux variability in tidal marshes may be more challenging than previously expected and highlight large discrepancies between manual and automated soil CO2 efflux measurements. New technical approaches are needed to implement long-term automated measurements of soil CO2 efflux across wetlands to properly estimate the carbon balance of these ecosystems. (C) 2021 Elsevier B.V. All rights reserved.
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