Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO₂) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m⁻² yr⁻¹. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m⁻² yr⁻¹ as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO₂ emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.

泥炭地的排水增加了氧化泥炭层的深度，并将其变成大气中的碳（C）来源。排水泥炭地的绿化可以帮助逆转这一过程，因为树木可以提高固碳能力。我们在2年的时间，在此期间，黑杨木（遵循S-冰岛的绿化排水泥炭地的C和水动力学欧洲大叶杨SSP。毛）种植为23-25岁。二氧化碳（CO ₂）的净生态系统交换（NEE））是用涡度协方差方法测量的，树木和地面植被的C库是用种群变化方法测量的。从每周的径流样品中估算出溶解的和颗粒状的有机碳（DOC，POC）的侧向损失。出乎意料的是，在两年中，绿化的排水泥炭地是一个强大的碳汇，平均NEE值为714 g C m ^-2 yr ^-1。通过横向DOC和POC传输，仅损失了全部NEE的0.5％，剩下710 g C m ^-2 yr ^-1作为生态系统总净产量（NEP）。钙 观察到的NEP的91％可以用黑杨木的年生物量增加来解释，而1.3％可以用地面植被来解释。这意味着剩余NEP总量的7.5％最有可能在泥炭土壤和垫料中积累，从而促进了土壤C储量。休眠季节的CO ₂排放量出乎意料地低，这可以通过ca外的排水点的高地下水位来解释。活跃生长季节的5个月。估计平均每年有66％的降水已蒸发回大气层。这留下了416毫米的潜在径流，该值略低于测得的径流（662毫米）。这些结果表明，在大约年龄段。在20-25年间，植树造林是一种有效的方法，可以逆转冰岛这片耗水草场的预期负C平衡。尽管该地点目前是土壤碳汇，但仍需要使用过程模型进行仿真研究，以测试在经过多次林分轮作后进行林业管理时，这些地点是否仍可能是碳汇。