Data from: Biogenic silica accumulation varies across tussock tundra plant functional type

1. Silica (SiO2) accumulation by terrestrial vegetation is an important component of the biological silica cycle because it improves overall plant fitness and influences export rates of silica from terrestrial to marine systems. However, most research on silica in plants has focused on agricultural and forested ecosystems, and knowledge of terrestrial silica cycling in the Arctic, as well as the potential impacts of climate change on the silica cycle is severely lacking. 2. We quantified biogenic silica (BSi) accumulation in above and belowground portions of three moist acidic tundra (MAT) sites spanning a 300 km latitudinal gradient in central and northern Alaska, USA. We also examined plant silica accumulation across three main tundra types found in the Arctic (MAT, moist non-acidic tundra (MNT), and wet sedge tundra (WST)). 3. BSi concentrations in live Eriophorum vaginatum, a tussock-forming sedge that is the foundation species of tussock tundra, were not significantly (p<0.05) different across the three main sites. Concentrations of BSi in live aboveground tissue were highest in the graminoid species (0.55 ± 0.07 % BSi in sedges from WST, and 0.27 ± 0.01% in E. vaginatum across the three MAT sites). Both inter-tussock tundra species and shrubs contained substantially lower BSi concentrations than E. vaginatum. 4. Our results have implications for how shifts in vegetation cover associated with climatic warming may alter silica storage in tussock tundra vegetation. Our calculations suggest that shrub expansion via warming will increase BSi storage in Arctic land plants due to the higher biomass associated with shrub tundra, whereas conversion of tussock tundra to WST via permafrost thaw would produce the opposite effect in the terrestrial plant BSi pool. Such changes in the size of the terrestrial vegetation silica reservoir could have direct consequences for the rates and timing of silica delivery to receiving waters in the Arctic.

1. 陆生植被对二氧化硅（Silica, SiO₂）的累积作用是生物硅循环的重要组成部分，因其可提升植物整体适合度，并影响二氧化硅从陆地向海洋生态系统的输出速率。然而，当前针对植物中二氧化硅的研究多聚焦于农业与森林生态系统，学界对北极地区陆地硅循环的认知，以及气候变化对硅循环的潜在影响均存在严重不足。
2. 本研究针对美国阿拉斯加中部与北部沿300公里纬度梯度分布的3处湿润酸性苔原（moist acidic tundra, MAT）样地，定量测定了其地上与地下部分的生物硅（biogenic silica, BSi）累积量。此外，本研究还调查了北极地区三类主要苔原类型中的植物硅累积特征，分别为湿润酸性苔原（MAT）、湿润非酸性苔原（moist non-acidic tundra, MNT）与湿生莎草苔原（wet sedge tundra, WST）。
3. 作为丛苔原建群种的簇生莎草——活体羊胡子草（Eriophorum vaginatum），其体内的BSi浓度在三处主要样地间差异不具有统计学显著性（p<0.05）。活体地上组织的BSi浓度以草本类物种为最高：湿生莎草苔原样本中的莎草BSi浓度为0.55 ± 0.07%，三处MAT样地内羊胡子草的BSi浓度为0.27 ± 0.01%。丛间苔原物种与灌木的BSi浓度均显著低于羊胡子草。
4. 本研究结果可为气候变暖相关的植被覆盖变化如何改变丛苔原植被的硅储存能力提供参考。本研究的测算结果显示：气候变暖驱动的灌木扩张会因灌木苔原拥有更高的生物量，提升北极陆地植物的BSi储存量；而永久冻土融化导致丛苔原向湿生莎草苔原（WST）转化，则会对陆地植物BSi库产生相反的影响。陆地植被硅储库规模的此类变化，将直接影响北极地区硅向受纳水体输送的速率与时机。