Rewetting drained agricultural peatlands aids in restoring their original ecosystem functions, including carbon storage and sustaining unique biodiversity. 30–60 cm of topsoil removal (TSR) before rewetting for Sphagnum establishment is a common practice to reduce nutrient concentrations and greenhouse gas emissions, and increase water conductivity. However, the topsoil is carbon-dense and preservation in situ would be favorable from a climate-mitigation perspective. The effect of reduced TSR on Sphagnum establishment and nutrient dynamics on degraded and rewetted raised bogs remains to be elucidated. We conducted a two-year field experiment under Sphagnum paludiculture management with three TSR depths: no-removal (TSR0), 5–10 cm (TSR5), and 30 cm (TSR30) removal. We tested the effects of TSR on Sphagnum establishment and performance, nutrient dynamics, and hotspot methane emissions. After two years, TSR5 produced similar Sphagnum biomass as TSR30, while vascular plant biomass was highest in TSR0. All capitula nitrogen (N > 12 mg/g) indicated N-saturation. Phosphorus (P) was not limiting (N/P < 30), but a potential potassium (K) limitation was observed in year one (N/K > 3). In TSR0, ammonium concentrations were > 150 µmol/l in year one, but decreased by 80% in year two. P-concentrations remained high (c. 100 µmol/l) at TSR0 and TSR5, and remained low at TSR30. TSR30 and TSR5 reduced hotspot methane emissions relative to TSR0. We conclude that all TSR practices have their own advantages and disadvantages with respect to Sphagnum growth, nutrient availability and vegetation development. While TSR5 may be the most suitable for paludiculture, its applicability for restoration purposes remains to be elucidated. Setting prioritized targets when selecting the optimal TSR with peatland rewetting is pivotal.

重新润湿排干的农业泥炭地有助于恢复其原有的生态系统功能，包括碳储存和维持独特的生物多样性。在重新润湿泥炭藓生长之前去除 30-60 厘米的表土 (TSR)是减少养分浓度和温室气体排放并增加水电导率的常见做法。然而，表土的碳密度较高，从减缓气候变化的角度来看，就地保存将是有利的。TSR 降低对泥炭藓形成以及退化和再润湿的沼泽养分动态的影响仍有待阐明。我们在泥炭藓沼泽管理下进行了为期两年的田间实验，采用三种 TSR 深度：不去除（TSR0）、5-10 厘米（TSR5）和 30 厘米（TSR30）去除。我们测试了 TSR 对泥炭藓生长和性能、营养动态和热点甲烷排放的影响。两年后，TSR5 产生了与 TSR30 相似的泥炭藓生物量，而维管植物生物量在 TSR0 中最高。所有头状花序氮 (N > 12 mg/g) 均表明氮饱和。磷 (P) 不受限制 (N/P < 30)，但在第一年观察到潜在的钾 (K) 限制 (N/K > 3)。在 TSR0 中，第一年铵浓度 > 150 µmol/l，但第二年下降了 80%。TSR0 和 TSR5 时P 浓度保持较高水平（约100 µmol/l），而 TSR30 时 P 浓度保持较低水平。相对于 TSR0，TSR30 和 TSR5 减少了热点甲烷排放。我们的结论是，所有 TSR 实践在泥炭藓生长、养分利用率和植被发育方面都有各自的优点和缺点。虽然 TSR5 可能最适合沼泽养殖，但其用于恢复目的的适用性仍有待阐明。在选择泥炭地再润湿的最佳 TSR 时，设定优先目标至关重要。