Long-term mitigation of drought stimulates changes in the forest soil metagenome and alters decomposing microbial communities. PfynMetagenome

Climate change can alter the flow of nutrients and energy through terrestrial ecosystems. Using an inverse climate change field experiment in the central European Alps, we explored how long-term irrigation of a naturally drought-stressed pine forest altered the metabolic potential of the soil microbiome. Drought mitigation by a decade of irrigation stimulated profound changes in the functional capacity encoded in the soil metagenome, revealing alterations in carbon and nitrogen metabolism as well as regulatory processes protecting microorganisms from starvation and desiccation. Despite the structural and functional shifts from oligotrophic to copiotrophic microbial lifestyles under irrigation, degradation of cellulose and lignin was not affected, although different microbial taxa were involved in the degradation as determined by a time-series incubation experiment with 13C-labeled cellulose and lignin. These findings provide new insights into the impact of precipitation changes on the soil microbiome and associated ecosystem functioning in a drought-prone pine forest and will help to improve our understanding of alterations in biogeochemical cycling under a changing climate.

气候变化可改变陆地生态系统的养分与能量流动。本研究依托中欧阿尔卑斯山区的反向气候变化野外实验，探究了长期灌溉对自然干旱胁迫针叶林的土壤微生物组（soil microbiome）代谢潜能的影响。为期十年的灌溉缓解了干旱胁迫，显著改变了土壤宏基因组（soil metagenome）所编码的功能潜力，揭示碳、氮代谢以及保护微生物免受饥饿与干燥胁迫的调控过程均发生了改变。尽管灌溉条件下微生物的生活型从贫营养型（oligotrophic）向富营养型（copiotrophic）发生了结构与功能层面的转变，但纤维素与木质素的降解过程并未受到影响；经碳13标记（13C-labeled）纤维素与木质素的时序培养实验证实，参与降解的微生物类群发生了更替。本研究结果为降水变化对易受干旱胁迫针叶林的土壤微生物组及相关生态系统功能的影响提供了新见解，有助于深化我们对气候变化下生物地球化学循环改变的认识。