Climate warming is known to impact ecosystem composition and functioning. However, it remains largely unclear how soil microbial communities respond to long-term, moderate warming. In this study, we used Illumina sequencing and microarrays (GeoChip 5.0) to analyze taxonomic and functional gene compositions of the soil microbial community after 14 years of warming (at 0.8–1.0 °C for 10 years and then 1.5–2.0 °C for 4 years) in a Californian grassland. Long-term warming had no detectable effect on the taxonomic composition of soil bacterial community, nor on any plant or abiotic soil variables. In contrast, functional gene compositions differed between warming and control for bacterial, archaeal, and fungal communities. Functional genes associated with labile carbon (C) degradation increased in relative abundance in the warming treatment, whereas those associated with recalcitrant C degradation decreased. A number of functional genes associated with nitrogen (N) cycling (e.g., denitrifying genes encoding nitrate-, nitrite-, and nitrous oxidereductases) decreased, whereas nifH gene encoding nitrogenase increased in the warming treatment. These results suggest that microbial functional potentials are more sensitive to long-term moderate warming than the taxonomic composition of microbial community.

众所周知，气候变暖会影响生态系统的组成和功能。然而，目前还不清楚土壤微生物群落如何对长期、温和的变暖做出反应。在这项研究中，我们使用 Illumina 测序和微阵列 (GeoChip 5.0) 分析了 14 年变暖（0.8-1.0 °C 持续 10 年，然后 1.5-2.0 °C 持续 4 年）土壤微生物群落的分类和功能基因组成。年）在加利福尼亚草原。长期变暖对土壤细菌群落的分类组成以及任何植物或非生物土壤变量都没有可检测到的影响。相比之下，细菌、古细菌和真菌群落的功能基因组成在变暖和控制之间存在差异。与不稳定碳（C）降解相关的功能基因在升温处理中相对丰度增加，而那些与顽固的 C 降解相关的减少。许多与氮 (N) 循环相关的功能基因（例如，编码硝酸盐、亚硝酸盐和一氧化二氮还原酶的反硝化基因）减少，而nifH基因编码固氮酶在加温处理中增加。这些结果表明，与微生物群落的分类组成相比，微生物功能潜力对长期温和变暖更敏感。