The agricultural use of peatlands usually requires drainage, thereby transforming these organic soils from a net carbon sink into a net source. The Seeland region of Switzerland is characterised by fens that have been intensively used for agriculture for 150 years. Our site is a degraded fen with a remaining peat layer of 60 cm that had been used as cropland until 2009. In connection to a nature protection project it has been managed as extensive permanent grassland since then. The net ecosystem carbon balance (NECB) was determined for two years (2015-2016). For this purpose, the net ecosystem exchange of CO₂ (NEE) and CH₄ fluxes were measured by eddy covariance, and the carbon removed by harvest was quantified. Our degraded fen site was found to be a net carbon source of 477±73g C m⁻² yr ^-1 and 434±51 g C m^-2 yr⁻¹ in 2015 and 2016, respectively. Annual CH₄ emissions were marginal in both years with 0.4±0.8 g CH₄-C m⁻² yr ^-1 (2015) and 0.7±0.7 g CH₄-C m⁻² yr ^-1 (2016). In contrast to NECB, the NEE was considerably higher in 2015 than in 2016 (308±71 g C m⁻² yr ^-1 vs 117±39 g C m⁻² yr ^-1). The year 2015 was characterised by partial flooding of the grassland, followed by a dry and hot summer leading to lower CO₂ uptake due to reduced growth, which was reflected in lower harvest compared to 2016. Thus, the short-term plant-induced carbon fluxes were altered, whereas total soil carbon loss remained rather constant. This was verified by an intra site comparison between the flooded and non-flooded part in 2015. Our results indicate that the soil carbon loss of this highly degraded peatland with a shallow peat layer is relatively moderate and hardly influenced by interannual weather variations.

泥炭地的农业用途通常需要排水，从而将这些有机土壤从净碳汇转变为净碳源。瑞士的Seeland地区的特点是芬斯，这些芬斯已被广泛用于农业150年。我们的土地是退化的，剩余的60厘米的泥炭层一直用作农田，直到2009年。与自然保护项目有关，此后一直作为广阔的永久草地进行管理。确定了两年（2015-2016年）的生态系统净碳平衡（NECB）。为此，通过涡度协方差测量了CO ₂（NEE）和CH ₄通量的净生态系统交换，并对收获时去除的碳进行了定量。发现我们降解的芬站点是477±73g C m的净碳源2015年和2016年分别为⁻²  yr ^-1和434±51 g C m ^-2  yr ^-1。在这两个年度中，CH _4的年排放量均很小，分别为0.4±0.8 g CH ₄ -C m ^-2 yr ^-1（2015）和0.7±0.7 g CH ₄ -C m ^-2 yr ^-1（2016）。与NECB相比，2015年的NEE显着高于2016年（308±71 g C m ^-2 yr ^-1和117±39 g C m ^-2 yr ^-1）。2015年的特点是草原局部被洪水淹没，随后是炎热干燥的夏季，导致CO ₂降低与2016年相比，收成减少，这是由于生长减少导致的吸收。因此，短期植物诱导的碳通量发生了变化，而土壤总碳损失却保持恒定。2015年对淹没和未淹没部分进行了现场比较，这证明了这一点。我们的结果表明，该高度退化的泥炭地浅层泥炭土的土壤碳损失相对中等，几乎不受年际天气变化的影响。