Abstract Afforestation of marginal cultivated land is an internationally approved climate mitigation strategy, however, with uncertain implications for soil organic carbon (SOC) storage. We examined the effect of forest planting by measuring SOC at two adjacent sites: one with a Norway spruce forest planted in 1968 and one actively grazed pasture. Both sites had similar land-use history before forest planting, and they were as similar as possible in all other edaphic factors. There were no significant differences in SOC stocks down to 30 cm mineral soil, 7.15 and 8.51 kg C m−2 in the forest plantation and pasture respectively. Only a minimal build-up of an O horizon, less than 2 cm, was observed in the plantation. The SOC stocks of the plantation and pasture were not significantly different from that of a nearby old forest, 7.17 kg C m−2. When comparing these three land-uses we found that there were significant differences in the upper 10 cm of the soil with regard to other soil properties. Nitrogen (N) stock and pH were significantly lower in the old forest compared to the plantation, which again was significantly lower than that of the pasture. The opposite was the case for the C/N ratio. We conclude that there were no significant differences in SOC stocks in the upper 30 cm 50 years after afforestation with Norway spruce, but that there is still a legacy from the former cultivation that may influence both productivity and organic matter dynamics.

中文翻译：

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种植 50 年后，挪威牧场的植树造林并未导致土壤碳含量升高

摘要 边际耕地植树造林是一项国际认可的气候减缓战略，但对土壤有机碳 (SOC) 储存的影响尚不确定。我们通过测量两个相邻地点的 SOC 来检验森林种植的影响：一个是 1968 年种植的挪威云杉林，另一个是活跃放牧的牧场。两个地点在造林前具有相似的土地利用历史，并且它们在所有其他土壤因子方面都尽可能相似。森林种植园和牧场中 30 cm 矿质土壤、7.15 和 8.51 kg C m-2 的 SOC 储量没有显着差异。在种植园中仅观察到最小的 O 层积聚，小于 2 厘米。人工林和牧场的 SOC 储量与附近老林的 SOC 储量没有显着差异，为 7.17 kg C m-2。在比较这三种土地用途时，我们发现土壤上部 10 厘米的其他土壤特性存在显着差异。与人工林相比，旧林中的氮 (N) 储量和 pH 值显着较低，而人工林再次显着低于牧场。C/N 比的情况正好相反。我们得出的结论是，挪威云杉造林 50 年后上层 30 厘米的 SOC 储量没有显着差异，但仍存在可能影响生产力和有机物质动态的前种植遗产。与人工林相比，旧林中的氮 (N) 储量和 pH 值显着较低，而人工林再次显着低于牧场。C/N 比的情况正好相反。我们得出的结论是，挪威云杉造林 50 年后上层 30 厘米的 SOC 储量没有显着差异，但仍存在可能影响生产力和有机质动态的前种植遗产。与人工林相比，旧林中的氮 (N) 储量和 pH 值显着较低，而人工林再次显着低于牧场。C/N 比的情况正好相反。我们得出的结论是，挪威云杉造林 50 年后上层 30 厘米的 SOC 储量没有显着差异，但仍存在可能影响生产力和有机物质动态的前种植遗产。