Rhizosphere Mediation of Biosphere-Climate Feedbacks – Assessing Blue Carbon Cycling under Climate Change

生物圈-气候反馈的根际调节 – 评估气候变化下的蓝碳循环

• 批准号: 502681570
• 负责人: Dr. Peter Mueller
• 金额: --
• 依托单位: Institut für Landschaftsökologie
• 依托单位国家: 德国
• 项目类别: Independent Junior Research Groups
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/502681570?language=en
• 关键词: Rhizosphere; Mediation; Biosphere; Climate; Feedbacks

Climate-driven alterations in soil abiotic conditions can directly affect microbial communities and thereby carbon and greenhouse-gas (GHG) fluxes to the atmosphere. In addition to direct climate-change effects (CCEs) on soil microbial carbon cycling, plant responses to climate change can act as a strong –sometimes overriding– mediator of CCEs on soil microbial communities. These plant-mediated effects are most pronounced in the rhizosphere and are determined by plant physiological and morphological trait expressions. However, the link between plant traits, soil microbial functioning, and carbon fluxes is poorly developed, which represents a key knowledge gap in informing models of ecosystem-climate feedbacks. I argue that plant-mediated effects on soil microbial carbon cycling are particularly important in wetland ecosystems because here plants not only control the microbial substrate supply, they also regulate the availability of electron acceptors by providing oxygen to an reducing soil system. At the same time, wetland soil microbial carbon cycling plays a disproportionately large role in the climate system, because low rates of microbial activity have caused wetlands to sequester the largest soil organic carbon (SOC) stock in the biosphere, representing a vast potential source of GHG to the atmosphere if unlocked by climate change. The central objective of this Emmy Noether project is to understand the mechanisms by which plants mediate CCEs on wetland SOC stock stability and GHG emissions through investigations of plant-trait responses and their interactions with soil microbial communities. Studies will be focused on tidal wetlands, semi-terrestrial ecosystems at the interface of land and sea that have been increasingly recognized for their outsized leverage over the global carbon cycle under the term ‘blue carbon’. The work comprises four complementary subprojects (SPs) that assess soil microbial carbon cycling from a plant-trait perspective. SP1 will provide the mechanistic basis by identifying the plant traits that control wetland SOC decomposition via rhizosphere priming effects, and determine how priming effects relate to overall wetland GHG emissions. This knowledge will be applied to address the project’s central question in SP2: How do plants mediate the effects of climate change on wetland SOC stock stability and GHG emissions? SP2 will quantify the interactions between plant traits and microbial carbon cycling along climate-sensitive environmental gradients, focusing on individual plant-level responses (i.e. phenotypic plasticity) and community-level responses. SP3 will complement this work by exploring population-level responses (i.e. intraspecific genotypic variation) as a yet overlooked additional level of plant-mediated CCEs on soil microbial carbon cycling. The synthesis, SP4, will compare and summarize the findings of the experimental SPs and advance their future integration into numerical models on wetland carbon cycling.

气候驱动的土壤非生物条件变化可以直接影响微生物群落，从而影响大气中的碳和温室气体（GHG）通量。除了气候变化对土壤微生物碳循环的直接影响外，植物对气候变化的反应可以作为 CCE 对土壤微生物群落的强大（有时是压倒性的）调节因素。这些植物介导的效应在根际最为明显，并由植物生理和形态特征表达决定。然而，植物性状、土壤微生物功能和碳通量之间的联系还很薄弱，这代表了生态系统-气候反馈模型中的一个关键知识差距。我认为植物介导的对土壤微生物碳循环的影响在湿地生态系统中特别重要，因为在这里植物不仅控制微生物底物供应，还通过向还原性土壤系统提供氧气来调节电子受体的可用性。与此同时，湿地土壤微生物碳循环在气候系统中发挥着不成比例的重要作用，因为微生物活动率低导致湿地封存了生物圈中最大的土壤有机碳（SOC）库，如果气候变化释放出来，这将成为大气中温室气体的巨大潜在来源。 Emmy Noether 项目的中心目标是通过研究植物性状反应及其与土壤微生物群落的相互作用，了解植物调节湿地 SOC 库稳定性和温室气体排放的 CCE 的机制。研究将集中于潮汐湿地、陆地和海洋交界处的半陆地生态系统，这些生态系统因其对全球碳循环的巨大影响力而日益受到认可，被称为“蓝碳”。这项工作包括四个补充子项目（SP），从植物性状的角度评估土壤微生物碳循环。 SP1 将通过识别通过根际启动效应控制湿地 SOC 分解的植物性状提供机制基础，并确定启动效应与湿地温室气体排放总量的关系。这些知识将应用于解决 SP2 中项目的核心问题：植物如何调节气候变化对湿地 SOC 库稳定性和温室气体排放的影响？ SP2将沿着气候敏感的环境梯度量化植物性状和微生物碳循环之间的相互作用，重点关注个体植物水平的响应（即表型可塑性）和群落水平的响应。 SP3 将通过探索群体水平的反应（即种内基因型变异）来补充这项工作，作为土壤微生物碳循环中植物介导的 CCE 的一个尚未被忽视的额外水平。 SP4 综合报告将比较和总结实验 SP 的结果，并推动它们未来融入湿地碳循环数值模型。