Peatlands store one-third of Earth's soil carbon, the stability of which is uncertain due to climate change-driven shifts in hydrology and vegetation, and consequent impacts on microbial communities that mediate decomposition. Peatland carbon cycling varies over steep physicochemical gradients characterizing vertical peat profiles. However, it is unclear how drought-mediated changes in plant functional groups (PFGs) and water table (WT) levels affect microbial communities at different depths. We combined a multiyear mesocosm experiment with community sequencing across a 70-cm depth gradient, to test the hypotheses that vascular PFGs (Ericaceae vs. sedges) and WT (high vs. low) structure peatland microbial communities in depth-dependent ways. Several key results emerged. (i) Both fungal and prokaryote (bacteria and archaea) community structure shifted with WT and PFG manipulation, but fungi were much more sensitive to PFG whereas prokaryotes were much more sensitive to WT. (ii) PFG effects were largely driven by Ericaceae, although sedge effects were evident in specific cases (e.g., methanotrophs). (iii) Treatment effects varied with depth: the influence of PFG was strongest in shallow peat (0–10, 10–20 cm), whereas WT effects were strongest at the surface and middle depths (0–10, 30–40 cm), and all treatment effects waned in the deepest peat (60–70 cm). Our results underline the depth-dependent and taxon-specific ways that plant communities and hydrologic variability shape peatland microbial communities, pointing to the importance of understanding how these factors integrate across soil profiles when examining peatland responses to climate change.

中文翻译：

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泥炭地微生物群落对植物功能群和干旱的响应是深度依赖的

泥炭地储存了地球土壤碳的三分之一，由于气候变化驱动的水文和植被变化，以及随之而来的对介导分解的微生物群落的影响，泥炭地的稳定性是不确定的。泥炭地碳循环在表征垂直泥炭剖面的陡峭物理化学梯度上变化。然而，尚不清楚干旱介导的植物功能群 (PFG) 和地下水位 (WT) 水平的变化如何影响不同深度的微生物群落。我们将多年中胚层实验与 70 厘米深度梯度的群落测序相结合，以测试血管 PFG（杜鹃花科与莎草）和 WT（高与低）以深度依赖方式构建泥炭地微生物群落的假设。出现了几个关键结果。(i) 真菌和原核生物（细菌和古细菌）群落结构都随着 WT 和 PFG 的操作而改变，但真菌对 PFG 更敏感，而原核生物对 WT 更敏感。(ii) PFG 效应主要由杜鹃花科驱动，尽管莎草效应在特定情况下（例如甲烷氧化菌）很明显。(iii) 处理效果随深度变化：PFG 的影响在浅层泥炭（0-10、10-20 cm）中最强，而 WT 效果在表层和中层深度（0-10、30-40 cm）最强，并且所有处理效果在最深的泥炭（60-70 cm）中减弱。我们的结果强调了植物群落和水文变异塑造泥炭地微生物群落的深度依赖和分类群特异性方式，