Microorganisms play pivotal roles in soil processes. Metabolically related microorganisms constitute functional groups, and diverse microbial functional groups control nutrient cycling in soils. This study explored environmental (i.e., rainfall, temperature) and soil factors driving the distribution of bacterial functional groups involved in soil carbon (C) cycling in paired natural and agricultural ecosystems. Soil samples were collected at a regional scale covering gradients of temperature and rainfall across two orthogonal transects (~1000 km) in New South Wales, Australia. Putative functions of bacteria were linked to two soil C fractions: particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). We found: (i) temperature and rainfall were important drivers of bacterial functional groups, while soil properties, such as pH, soil C and nitrogen (N), also presented significant contributions; (ii) community structure of bacteria involved in C cycling was mainly related to POC content but not to MAOC; (iii) paired sampling showed that agricultural practices had significant impacts on the composition and responses of soil bacterial functional groups. This study demonstrated the environmental regulation (e.g., temperature and rainfall) of soil microbial functional groups at large scales, which was altered by agricultural practices.

中文翻译：

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涉及 C 循环的土壤细菌在广泛的环境和成土梯度中的分布

微生物在土壤过程中起着举足轻重的作用。代谢相关的微生物构成功能群，不同的微生物功能群控制着土壤中的养分循环。本研究探讨了环境（即降雨量、温度）和土壤因素，这些因素会影响成对的自然和农业生态系统中参与土壤碳 (C) 循环的细菌功能组的分布。土壤样本是在区域范围内收集的，涵盖澳大利亚新南威尔士州两个正交样带（~1000 公里）的温度和降雨梯度。细菌的假定功能与两种土壤碳组分有关：颗粒有机碳 (POC) 和矿物相关有机碳 (MAOC)。我们发现：(i) 温度和降雨量是细菌功能群的重要驱动因素，而土壤特性，如 pH 值，土壤碳和氮（N）也有显着贡献；(ii) 参与碳循环的细菌群落结构主要与 POC 含量相关，与 MAOC 无关；(iii) 配对抽样表明，农业实践对土壤细菌功能群的组成和响应有重大影响。这项研究证明了土壤微生物功能群在大范围内的环境调节（例如，温度和降雨），这会因农业实践而改变。