Altered microbial structure and function after thermokarst formation
Altered microbial structure and function after thermokarst formation
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热岩溶形成后微生物结构和功能的改变
DOI：
10.1111/gcb.15438
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发表时间：
2020-11-26
影响因子：
11.6
通讯作者：
Yang, Yuanhe
中科院分区：
文献类型：
--
作者：
Liu, Futing;Kou, Dan;Yang, Yuanhe
多年冻土融化会导致大量的碳排放到大气中，从而引发气候变暖的正反馈。土壤微生物作为地球化学循环的发动机，在调节冻土碳-气候反馈的方向和强度方面发挥着关键作用。然而，我们对热岩溶（冻土突然融化）对微生物结构和功能的影响的了解仍然有限。在这里，我们采用宏基因组测序分析了青藏高原冻土融化序列（冻土塌陷后1年，10年和16年）的表土（0-15 cm）微生物群落和功能基因沿着的变化。通过结合实验室培养和双库模型，我们探讨了土壤不稳定和稳定碳分解沿着解冻序列的变化。结果表明，与未塌陷对照相比，塌陷初期（塌陷后1年）土壤微生物α多样性下降，而群落结构和功能基因丰度没有发生显著变化。但随着塌陷时间的延长，表层土壤微生物群落结构和功能基因均与对照不同。不稳定的C降解的功能基因的丰度下降，而稳定的C降解的增加，在崩溃的后期阶段（崩溃后16年），主要是由基板性能的变化沿着解冻序列。因此，与对照相比，在塌陷的后期发生更快的稳定C分解，这与稳定C降解的功能基因的相对丰度的增加有关。这些结果表明，高地热岩溶改变微生物的结构和功能，特别是通过调节微生物功能基因，这可能会加强在十年的时间尺度上的气候变暖，土壤稳定C分解增强。
Permafrost thaw could induce substantial carbon (C) emissions to the atmosphere, and thus trigger a positive feedback to climate warming. As the engine of biogeochemical cycling, soil microorganisms exert a critical role in mediating the direction and strength of permafrost C-climate feedback. However, our understanding about the impacts of thermokarst (abrupt permafrost thaw) on microbial structure and function remains limited. Here we employed metagenomic sequencing to analyze changes in topsoil (0-15 cm) microbial communities and functional genes along a permafrost thaw sequence (1, 10, and 16 years since permafrost collapse) on the Tibetan Plateau. By combining laboratory incubation and a two-pool model, we then explored changes in soil labile and stable C decomposition along the thaw sequence. Our results showed that topsoil microbial alpha-diversity decreased, while the community structure and functional gene abundance did not exhibit any significant change at the early stage of collapse (1 year since collapse) relative to non-collapsed control. However, as the time since the collapse increased, both the topsoil microbial community structure and functional genes differed from the control. Abundances of functional genes involved in labile C degradation decreased while those for stable C degradation increased at the late stage of collapse (16 years since collapse), largely driven by changes in substrate properties along the thaw sequence. Accordingly, faster stable C decomposition occurred at the late stage of collapse compared to the control, which was associated with the increase in relative abundance of functional genes for stable C degradation. These results suggest that upland thermokarst alters microbial structure and function, particularly enhances soil stable C decomposition by modulating microbial functional genes, which could reinforce a warmer climate over the decadal timescale.