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（Silica, SiO₂）的累积是生物硅循环的重要组成环节，其不仅可提升植物整体生存适合度，还会影响二氧化硅从陆地向海洋系统的输出速率。然而，当前针对植物体内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. 本研究对美国阿拉斯加中北部沿300公里纬度梯度分布的3处湿润酸性苔原（moist acidic tundra, MAT）样地的地上、地下部分的生物硅（biogenic silica, BSi）累积量开展了定量测定。此外，我们还探究了北极地区3类主要苔原类型（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））的植物硅累积特征。3. 作为草丘苔原的优势物种、形成草丘的莎草科植物羊胡子草（Eriophorum vaginatum），其活体组织的生物硅浓度在3处主要样地间无显著差异（p<0.05）。活体地上组织的生物硅浓度以草本植物类群最高：湿生莎草苔原中的莎草科植物生物硅含量为0.55 ± 0.07 %，3处湿润酸性苔原样地的羊胡子草生物硅含量为0.27 ± 0.01 %。草丘间苔原物种与灌木的生物硅浓度均显著低于羊胡子草。4. 本研究结果可为解析气候变暖相关的植被覆盖变化如何改变草丘苔原植被的硅存储量提供参考。我们的测算显示，气候变暖引发的灌木扩张，会因灌木苔原拥有更高的生物量，进而提升北极陆地植物的生物硅存储量；而永久冻土融化导致草丘苔原向湿生莎草苔原转化，则会对陆地植物生物硅库产生相反的影响。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向受纳水体输送的速率与时机。