Nutrient and Metal Amounts in Permafrost and Active Layer Soils at the Stordalen Mire, Abisko Sweden

We assessed how nutrients, solutes, and metals vary in permafrost soil and in the active layers across four plant communities undergoing permafrost thaw at the Stordalen Mire in Abisko Sweden. We hypothesized that nutrient availability shifts from low nitrogen and phosphorus to high nitrogen and phosphorus amounts across plant communities with increasing thaw depth. Although nutrient availability did not shift from low to high nitrogen and phosphorus across plant communities with increasing thaw depth as hypothesized, nutrient availability immediately increased in the thaw front (rich Sphagnum lawn), and returned to low nitrogen and phosphorus availability in the tall graminoid fen, where permafrost was no longer intact. Despite high amounts of acid digestible phosphorus, available P (Presin) amount was low in the permafrost and tall graminoid fen soils, likely due to P sorption with iron. While permafrost soils had high amounts of nitrogen, phosphorus, and metals, dissolved organic carbon amounts were low.本研究针对瑞典阿比斯科斯托达伦泥炭地（Stordalen Mire）内4个正经历永久冻土融化的植物群落，评估了永久冻土土壤与活动层（active layer）中养分、溶质及金属元素的变化特征。我们提出假设：随着解冻深度增加，不同植物群落的养分有效性将从低氮、低磷状态转向高氮、高磷水平。尽管养分有效性并未如假设般随解冻深度增加在各植物群落间呈现从低氮磷至高氮磷的转变，但在解冻锋面（富营养泥炭藓（Sphagnum）草坪）中，养分有效性会迅速升高；而在永久冻土已不复存在的高大禾草沼泽中，养分有效性又回落至低氮磷水平。尽管永久冻土与高大禾草沼泽土壤中的酸可消化磷含量较高，但有效磷（Presin）浓度却处于低位，这大概率是由于磷与铁发生吸附作用所致。虽然永久冻土土壤的氮、磷与金属元素含量较高，但溶解有机碳浓度却处于较低水平。