Project coordination: Field site management, data synthesis and modeling of subsoil C-turnover

底土有机质的高14 C年龄表明周转率非常缓慢。然而，存档的土壤样品和14 CO2和DO 14 C通量测量的分析表明，相当大的一部分底土碳库具有年度至十年的周转时间，从而有助于全球Ccycle。优先流径和非优先流径土壤14 C含量和微生物活性的显著差异表明，土壤有机质（SOM）的长期稳定性也可能与其与微生物活性热点的空间分离有关。其他底土的具体因素，如低O2分压，低温和低水分动态可能会额外控制SOM营业额。为了模拟C-动力学在底土中，这些因素的影响与营业额的基本机制需要了解和量化，只要可能。此外，必须对碳通量进行量化，并确定其来源。这一协调分项目的中心目标是确保各分项目之间的密切协作，以便汇编和综合所有相关结果，用于模型开发。为此，将详细规划和协调底土观测站的建立和安装以及所有实地活动，如取样活动、通量测量和额外的实地实验。为此，将建立一个网上共同数据库和交流平台，并定期更新所有参与者均可查阅的所有活动一览表。底土观测站将由一名技术员管理。协调科学家将定期召集与其他小组或小组的会议，讨论结果和协调实验。此外，他/她还将为参与的博士生组织暑期学校，并举办讲习班，向国际受众宣传成果。汇编数据的C-通量和14 C分析将被合成，以获得更好的理解C动态底土的概念模型，它将被用作输入参数的改进和适应的数值模型的C-营业额在土壤中。数值模型的开发和验证是博士生的任务。

The high 14C age of subsoil organic matter suggests very slow turnover rates. However, analyses of archived soil samples and 14CO2 and DO14C flux measurements indicate that a sub-stantial part of the subsoil C-pool has annual to decadal turnover times and thus contributes to the global Ccycle. Distinct differences in 14C content and microbial activity between preferential flow paths and bulk soil indicate that the long-term stability of soil organic matter (SOM) may also result from its spatial segregation from hot spots of microbial activity. Other subsoil specific factors such as low O2 partial pressure, low temperatures and low moisture dynamics may additionally control SOM turnover. In order to model C-dynamics in subsoils, the influence of these factors with the underlying mechanisms on turnover needs to be understood and quantified wherever possible. In addition, C-fluxes have to be quantified and their sources have to be identified. The central objective of this coordination subproject is to ensure the close collaboration between the subprojects in order to compile and synthesize all relevant results for model development. To this end, the set-up and installation of the subsoil observatories and all field activities like sampling campaigns, flux measurements and additional field experiments will be planned in detail and coordinated by this project. This will be supported by the creation of a web-based common database and communication platform together with a regularly updated table of all activities accessible to all participants. The subsoil observatory will be managed by a technician. The coordinating scientist will regularly call in meetings with the other groups or with subgroups for discussion of results and coordination of experiments. Furthermore he/she will organize a summer school for the participating PhD students and workshops for the communication of results to an international audience. The compiled data on C-fluxes and 14C analyses will be synthesized to gain an improved understanding of C dynamics in subsoils with a conceptual model and it will be used as input parameters for the improvement and adaptation of a numerical model of C-turnover in soils. The development and validation of the numerical model is the task of a PhD-student.