Summary 1.Cut-away peatlands devoid of vegetation form a persistent source of carbon (C) to the atmosphere. The restoration of the C sink function in such areas can be facilitated by raising the water table.Planting vascular plants and Sphagnum may hasten the restoration process further. However, little is known about the effects of different species on the restoration process. 2. We studied carbon dioxide (CO 2 ) exchange in stands of different plants in a restored cut-away site over two growing seasons to quantify their ability to form a C sink. We sampled five different types of stand: monocultures of Eriophorum vaginatum and Carex rostrata (pure plots), mixtures of Eriophorum or Carex and Sphagnum mosses (mixed plots) and control plots without vegetation. We applied the closed chamber technique to gather CO 2 exchange data for modelling of gross photosynthesis (P G ) and ecosystem respiration (R E ). Finally, we used the models to reconstruct the seasonal net CO 2 exchange of the stands formed by different plants. , all the vegetated plots acted as C sinks during both growing seasons. The monostands of E. vaginatum and C. rostrata created sinks of 23-114 g CO 2 -C m -2 , while the mixtures of sedge and Sphagnum mosses resulted in larger sinks of 75-186 g CO 2 -C m -2 . The larger sinks of the mixed patches were due to the lower respiration/photosynthesis ratio. 4. To eliminate the effect of differences in water table and the abundance of sedges between the patches, we reconstructed the CO 2 exchange for constant water table and vascular leaf area for all plots. The simulation further supported our result: the mixtures of sedge and Sphagnum mosses were clearly more efficient in sequestering CO 2 than pure sedge stands. 5. Synthesis and applications. The increased functional diversity in a cut-away peatland site resulted in higher net ecosystem exchange. When restoring cut-away peatlands, reintroduction of Sphagna is recommended after the colonization of vascular plants to hasten the formation of a sink for C.

We measured the net ecosystem exchange (NEE) and respiration rates and modeled the photosynthesis and respiration dynamics in a cutover bog in the Swiss Jura Mountains during one growing season at three stages of regeneration (29, 42, and 51 years after peat cutting; coded sites A, B, and C) to determine if reestablishment of Sphagnum suffices to restore the C‐sequestration function. From the younger to the older stage Sphagnum cover increased, while net primary Sphagnum production over the growing season decreased (139, 82, and, 67 g m−2 y−1 for A, B, and C respectively), and fen plant species were replaced by bog species. According to our NEE estimations, over the vegetation period site A was a net CO2‐C source emitting 40 g CO2‐C/m2 while sites B and C were accumulating CO2‐C, on average 222 and 209 g CO2‐C/m2, respectively. These differences are due to the higher respiration in site A during the summer, suggesting that early regeneration stages may be more sensitive to a warmer climate. Methane fluxes increased from site A to C in parallel with Eriophorum vaginatum cover and vascular plant leaf area. Our results show that reestablishing a Sphagnum cover is not sufficient to restore a CO2‐sequestrating function but that after circa 50 years the ecosystem may naturally regain this function over the growing season.

We studied the restoration success of a cut-away peatland 10 years after restoration by comparing the vegetation and CO 2 dynamics with those of a pristine peatland of similar nutrition level and climate. Vegetation and CO 2 dynamics were monitored during one growing season. We used DCA (detrended correspondence analysis) and diversity indices to study the vegetation composition within and between the sites, and non-linear regression models to estimate the seasonal CO 2 fluxes and balances of the sites. Based on both DCA and diversity indices, the study plots in the restored site differed more in the vegetation composition than the study plots in the pristine site. The variation in the CO 2 fluxes and balance was greater in the restored than in the pristine site, resulting from the heterogeneous vegetation in the restored site. The seasonal net CO 2 balance was positive (sink) at both sites, the restored site binding on average 500 ± 410 g CO 2 /m 2 and the pristine site 390 ± 265 g CO 2 /m 2 (statistically not different, p = 0.575). The results indicate that the restoration of the vegetation composition is still incomplete but the vegetation coverage is sufficient for the restored site to function as a sink of atmospheric CO 2 .