Addressing Effects of Environment on Eddy-Covariance Flux Estimates at a Temperate Sedge-Grass Marsh

0571779 - ÚVGZ 2024 RIV NL eng J - Journal Article
Kivalov, Sergey N. - Dušek, Jiří - Czerný, Radek - Jocher, Georg - Pavelka, Marian - Fitzjarrald, D.R. - Dařenová, Eva - Šigut, Ladislav - Kowalska, Natalia
Addressing Effects of Environment on Eddy-Covariance Flux Estimates at a Temperate Sedge-Grass Marsh.
Boundary Layer Meteorology. Roč. 186, č. 2 (2023), s. 217-250. ISSN 0006-8314. E-ISSN 1573-1472
R&D Projects: GA MŠMT(CZ) EF16_019/0000797; GA MŠMT(CZ) LM2018123
Institutional support: RVO:86652079
Keywords : Eddy covariance * Carbon balance * Wetland * Urban surroundings * Katabatic drainage flow * High relative humidity
OECD category: Meteorology and atmospheric sciences
Impact factor: 4.3, year: 2022
Method of publishing: Open access
https://link.springer.com/article/10.1007/s10546-022-00755-0

We examined the net-ecosystem-exchange (NEE)-based annual carbon-balance estimates obtained from eddy-covariance (EC) measurements at an unmanaged sedge-grass marsh ecosystem (Trebon, Czech Republic, 49 degrees 1' N, 14 degrees 46' E), seeking methods to improve the EC measurements in inhomogeneous environment. The data filtering procedure was developed using three thresholds: (a) a stationarity test, (b) a stability u(SIC)threshold, and (c) a high relative humidity RH-threshold. This procedure was tested in 2014, a year without significant floods and drought events led to a stable water table, reducing the effect of soil respiration on the EC measurements. Estimates of annual carbon-balance were reduced from 182 to 234 +/- 12 gC m(-2) year(-1) for the initial data to 39-44 +/- 8 gC m(-2) year(-1 )after the RH <= 95% filtering and to 24-26 +/- 7 gC m-2 year(-1) after the further u,,, >= 0.1 m s-1 filtering. Applying the precipitation/fog threshold reduced this balance to 10-12 +/- 7 gC m-2 year(-1), closer to carbon neutrality. Up to 9.5% of this identified shift occurred during apparent nocturnal downslope katabatic drainage flows or plume descent coming from the nearby town of Trebon. High-RH conditions account for up to 27% of this shift. Moreover, both conditions together account for an additional 67% of the identified carbon-balance change. Removing these non-ecosystem-related processes brings EC measurements closer to values of an unmanaged-ecosystem productivity, providing a better NEE-based estimate for the net ecosystem production. The presented procedure is applicable to EC measurements conducted at different wetlands or terrestrial ecosystems with similar conditions.
Permanent Link: https://hdl.handle.net/11104/0342961