Process-based modelling of CO2 fluxes in Vlist

To distinguish processes affecting CO2 emissions and to disentangle sources contributing to these emissions, the process-based models PEATLAND-VU and SWAP-ANIMO were applied to the NOBV location Vlist. CO2 fluxes and other environmental variables were modelled for both the reference and PWIS parcel, of which the latter was equipped with a passive water infiltration system (PWIS; submerged drains) to allow for extra water infiltration in summer. Model outcomes were compared to measurements of chamber CO2 fluxes (with a high temporal resolution) and long-term soil subsidence measurements, and to results of the PP2D-AAP and HYDRUS-AAP models for the same location.Model results generally show good agreement with measured hydrological variables and CO2 fluxes throughout the year. The net ecosystem carbon balances (NECB), determined with the two models are in good agreement with the measured chamber NECB for the year 2020. For the year 2021 the modelled NECB is slightly higher for the reference parcel (~2 t CO2 ha-1 yr-1) and PWIS parcel (~3-4 t CO2 ha-1 yr-1) than the measured NECB. This leads to differences in measured and modelled CO2 emission reductions in the parcel with PWIS compared to the reference. An emission reduction of 6.6 (31%) and 3.1 (25%) t CO2 ha-1 yr-1 was found with chamber measurements for 2020 (dry) and 2021 (wet), respectively, compared to 4.8 (24%) and 0.7 (5%) t CO2 ha-1 yr-1 for PEATLAND-VU, and 3.9 (21%) and 0.9 (7%) t CO2 ha-1 yr-1 for SWAP-ANIMO for the same years. Reductions from PP2D-AAP (0.6 and –0.5 t CO2 ha-1 yr-1 (3 and -3 %)) and HYDRUS-AAP (6.2 and –0.5 t CO2 ha-1 yr-1 (28 and -4 %)) form the outer model prediction bounds in 2020 and predict an increase in emission from the PWIS parcel in 2021.Accounting for CO2 emission derived from peat oxidation only, the modelled emission is lower than the modelled NECB: 14.1 and 12.9 t CO2 ha-1 yr-1 (compared to an NECB of 17.0 and 14.3 t CO2 ha-1 yr-1) for the reference and PWIS parcel for PEATLAND-VU, respectively, and 14.9 and 13.4 t CO2 ha-1 yr-1 (compared to an NECB of 17.9 and 15.5 t CO2 ha-1 yr-1) for the reference and PWIS parcel for SWAP-ANIMO, averaged over the two years. This is very well comparable with ten years of soil subsidence measurements in Vlist converted to CO2, with an average emission of 12 t CO2 ha-1 yr-1. The emission reduction from the PWIS parcel for peat oxidation is 2.4 and 0.0 t CO2 ha-1 yr-1 for PEATLAND-VU, and 2.8 and 0.3 t CO2 ha-1 yr-1 for SWAP-ANIMO for 2020 and 2021. This is also comparable to the estimated reduction of 1.1 t CO2 ha-1 yr-1 based on the long-term soil subsidence.

Bibliographic Details

Main Authors:	van de Craats, D., van den Berg, M., van Huissteden, Jacobus, van der Velde, Ype, Boonman, Jim
Format:	External research report biblioteca
Language:	English
Published:	Nationaal Onderzoeksprogramma Broeikasgassen Veenweiden
Subjects:	Life Science,
Online Access:	https://research.wur.nl/en/publications/process-based-modelling-of-co2-fluxes-in-vlist
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