Vincent Andrea G, Sundqvist Maja K, Wardle David A, Giesler Reiner
Department of Ecology and Environmental Sciences, Umeå University, Umeå, Sweden; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
PLoS One. 2014 Mar 27;9(3):e92942. doi: 10.1371/journal.pone.0092942. eCollection 2014.
Phosphorus (P) is an important macronutrient in arctic and subarctic tundra and its bioavailability is regulated by the mineralization of organic P. Temperature is likely to be an important control on P bioavailability, although effects may differ across contrasting plant communities with different soil properties. We used an elevational gradient in northern Sweden that included both heath and meadow vegetation types at all elevations to study the effects of temperature, soil P sorption capacity and oxalate-extractable aluminium (Alox) and iron (Feox) on the concentration of different soil P fractions. We hypothesized that the concentration of labile P fractions would decrease with increasing elevation (and thus declining temperature), but would be lower in meadow than in heath, given that N to P ratios in meadow foliage are higher. As expected, labile P in the form of Resin-P declined sharply with elevation for both vegetation types. Meadow soils did not have lower concentrations of Resin-P than heath soils, but they did have 2-fold and 1.5-fold higher concentrations of NaOH-extractable organic P and Residual P, respectively. Further, meadow soils had 3-fold higher concentrations of Alox + Feox and a 20% higher P sorption index than did heath soils. Additionally, Resin-P expressed as a proportion of total soil P for the meadow was on average half that in the heath. Declining Resin-P concentrations with elevation were best explained by an associated 2.5-3.0 °C decline in temperature. In contrast, the lower P availability in meadow relative to heath soils may be associated with impaired organic P mineralization, as indicated by a higher accumulation of organic P and P sorption capacity. Our results indicate that predicted temperature increases in the arctic over the next century may influence P availability and biogeochemistry, with consequences for key ecosystem processes limited by P, such as primary productivity.
磷（P）是北极和亚北极苔原中的一种重要常量营养素，其生物有效性受有机磷矿化作用的调节。温度可能是磷生物有效性的一个重要控制因素，尽管不同土壤性质的对比植物群落的影响可能有所不同。我们利用瑞典北部的一个海拔梯度，该梯度在所有海拔高度都包括了石南和草甸植被类型，以研究温度、土壤磷吸附能力以及草酸盐可提取铝（Alox）和铁（Feox）对不同土壤磷组分浓度的影响。我们假设，随着海拔升高（从而温度降低），不稳定磷组分的浓度会降低，但鉴于草甸叶片中的氮磷比更高，草甸中的浓度会低于石南。正如预期的那样，两种植被类型的树脂磷形式的不稳定磷都随着海拔急剧下降。草甸土壤的树脂磷浓度并不低于石南土壤，但它们的氢氧化钠可提取有机磷和残余磷浓度分别高出2倍和1.5倍。此外，草甸土壤的Alox + Feox浓度高出3倍，磷吸附指数比石南土壤高20%。此外，草甸中树脂磷占土壤总磷的比例平均是石南中的一半。树脂磷浓度随海拔下降最好用温度相关的2.5 - 3.0°C下降来解释。相比之下，草甸土壤相对于石南土壤较低的磷有效性可能与有机磷矿化受损有关，这表现为有机磷和磷吸附能力的较高积累。我们的结果表明，预计下个世纪北极地区的温度升高可能会影响磷的有效性和生物地球化学，对受磷限制的关键生态系统过程（如初级生产力）产生影响。
