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. 陆地植被对二氧化硅（SiO₂）的累积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生态系统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，关于北极陆地硅循环的认知，以及气候变化对硅循环的潜在影响均极度匮乏。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个湿润酸性苔原（moist acidic tundra, MAT）样地，定量分析了其地上与地下部分的生物源二氧化硅（biogenic silica, BSi）累积量。此外，本研究还探究了北极地区3种主要苔原类型（湿润酸性苔原（MAT）、湿润非酸性苔原（MNT）以及湿生薹草苔原（WST））中的植物硅素累积特征。3. 作为团簇苔原的建群种，形成草簇的薹草物种羊胡子草（Eriophorum vaginatum）的活体组织中BSi浓度在3个主要样地间无显著差异（p<0.05）。活体地上组织的BSi浓度以禾草类植物最高：湿生薹草苔原中的薹草类BSi浓度为0.55 ± 0.07%，3个湿润酸性苔原样地内羊胡子草的BSi浓度为0.27 ± 0.01%。团簇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团簇苔原植被的硅储存能力提供理论参考。计算结果表明，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的团簇苔原向湿生薹草苔原的转化，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，可能直接影响北极地区硅素向受纳水体输送的速率与时间节点。