Data_Sheet_1_Responses of soil micro-eukaryotic communities to decadal drainage in a Siberian wet tussock tundra.docx

Climate warming holds the potential to cause extensive drying of wetlands in the Arctic, but the warming-drying effects on belowground ecosystems, particularly micro-eukaryotes, remain poorly understood. We investigated the responses of soil micro-eukaryotic communities, including fungi, protists, and microbial metazoa, to decadal drainage manipulation in a Siberian wet tundra using both amplicon and shotgun metagenomic sequencing. Our results indicate that drainage treatment increased the abundance of both fungal and non-fungal micro-eukaryotic communities, with key groups such as Ascomycota (mostly order Helotiales), Nematoda, and Tardigrada being notably abundant in drained sites. Functional traits analysis showed an increase in litter saprotrophic fungi and protistan consumers, indicating their increased activities in drained sites. The effects of drainage were more pronounced in the surface soil layer than the deeper layer, as soils dry and warm from the surface. Marked compositional shifts were observed for both communities, with fungal communities being more strongly influenced by drainage-induced vegetation change than the lowered water table itself, while the vegetation effect on non-fungal micro-eukaryotes was moderate. These findings provide insights into how belowground micro-eukaryotic communities respond to the widespread drying of wetlands in the Arctic and improve our predictive understanding of future ecosystem changes.

气候变暖具备引发北极湿地大范围干涸的潜在可能，但目前学界对该变暖-干旱化效应对地下生态系统，尤其是微型真核生物（micro-eukaryotes）的影响仍缺乏充分认知。本研究依托扩增子（amplicon）与鸟枪宏基因组（shotgun metagenomic）测序技术，针对西伯利亚湿苔原开展的十年尺度排水操控实验，探究了土壤微型真核生物群落（涵盖真菌、原生生物（protists）与微型后生动物（microbial metazoa））的响应模式。研究结果显示，排水处理提升了真菌与非真菌型微型真核生物群落的丰度，子囊菌门（Ascomycota，主要类群为柔膜菌目Helotiales）、线虫动物门（Nematoda）以及缓步动物门（Tardigrada）等关键类群在排水样地中显著富集。功能性状分析表明，枯落物腐生真菌与原生生物消费者类群的丰度有所增加，反映出其在排水样地中的活性增强。由于土壤从表层开始逐渐干燥增温，排水处理的影响在表层土壤中较深层土壤更为显著。两类群落均出现了显著的组成结构偏移：真菌群落受排水引发的植被变化的影响程度远高于地下水位下降本身，而植被变化对非真菌型微型真核生物的影响则较为温和。本研究结果揭示了北极湿地大范围干涸背景下地下微型真核生物群落的响应规律，有助于深化我们对未来生态系统变化的预测性认知。