Abstract Despite knowledge of the interaction between climate change factors significant uncertainty exists concerning the individual and interactive effects of elevated carbon dioxide (eCO2) and elevated temperature (eT) on the soil microbiome and function. Here we examine the individual and interactive effects of eCO2 and eT on tree growth, soil respiration (Rsoil), biomass, structural and functional composition of microbial community, nitrogen (N) mineralisation and N availability in a whole tree chamber experiment. Eucalyptus globulus plants were grown from seedling to ca. 10 m tall for 15 months in a nutrient-poor sandy soil under ambient and elevated (+ 240 ppm) atmospheric CO2 concentrations combined with ambient or elevated temperatures (+ 3 °C) in a full factorial design. Plant growth was strongly stimulated under eCO2, but eT had little impact on any measured plant property. In contrast, Rsoil was not consistently affected by eCO2 or eT, but correlated strongly with root and leaf biomass. The response of N-mineralisation and nutrient availability to eCO2 and eT varied across time, and available N correlated strongly with plant height. Further, the C:N ratio of the microbial biomass and leaves were both higher under eCeT treatment. However, these functional measures were not significantly linked to either structural or functional diversity of the soil microbiome. Taken together, these results suggest that in this low-nutrient soil, belowground processes are principally driven by aboveground productivity. Our work provides novel insight into mechanisms underlying above- and belowground response to climate change, and the potential to sequester C in a low-nutrient status soil under future climatic conditions may be limited.

中文翻译：

---

在营养有限的土壤中，植物生产力是土壤呼吸响应气候变化的关键驱动因素。

摘要 尽管了解气候变化因素之间的相互作用，但在二氧化碳 (eCO2) 升高和温度升高 (eT) 对土壤微生物群落和功能的个体和相互作用影响方面存在重大不确定性。在这里，我们在整个树室实验中检查了 eCO2 和 eT 对树木生长、土壤呼吸 (Rsoil)、生物量、微生物群落的结构和功能组成、氮 (N) 矿化和氮可用性的个体和交互影响。Eucalyptus globulus 植物从幼苗生长到大约。在全因子设计中，在环境和升高 (+ 240 ppm) 大气 CO2 浓度以及环境或升高的温度 (+ 3 °C) 下，在营养贫乏的沙质土壤中保持 10 m 高 15 个月。在 eCO2 下，植物生长受到强烈刺激，但 eT 对任何测量的植物属性几乎没有影响。相比之下，Rsoil 并未始终受到 eCO2 或 eT 的影响，但与根和叶生物量密切相关。氮矿化和养分有效性对 eCO2 和 eT 的响应随时间变化，可用 N 与植物高度密切相关。此外，在 eCeT 处理下，微生物生物量和叶子的 C:N 比都更高。然而，这些功能测量与土壤微生物组的结构或功能多样性没有显着联系。总之，这些结果表明，在这种低营养土壤中，地下过程主要是由地上生产力驱动的。我们的工作提供了对地上和地下气候变化响应机制的新见解，