Dissolved molecular signals as mediators of biodiversity effects

生物多样性与生态系统功能的正相关关系随着时间的推移而增强。这种强化应该由i）土壤群落的集合，例如微生物或动物群落，和/或ii）植物群落的发展来确定。在这两种情况下，植物群落和土壤群落之间的相互作用发生了变化。最有可能的是，这些相互作用及其变化是由分子交换介导的。然而，生物多样性如何影响分子交换，从而介导相互作用的问题很少被考虑在BEF研究。因此，本项目将利用先进的高分辨率质谱法分析植物和土壤微生物群落与土壤基质之间的相互作用。我们将分析溶解有机物的分子特征，以便更好地了解一般的正BEF关系，特别是随着时间的推移而加强。我们将使用土壤溶液和土壤提取物的非靶向方法比较具有不同历史的植物群落和土壤微生物群落之间的分子信号。利用田间试验，我们将调查一般的植物多样性对DOM组成的影响在现场条件下（WP 1），以及它是如何受到土壤历史（WP 2）。Ecotron实验中，具有不同群落历史的植物与具有不同历史的土壤杂交，将使我们能够评估植物与土壤历史对分子DOM组成的相对重要性（WP 3）。除了调查加强的BEF关系随着时间的推移的分子DOM组成的基础上，在Ecotron实验中的时间复制DOM采样将允许检测植物-微生物相互作用的时间变化。我们将与其他子项目密切合作，利用单变量和多变量统计和网络分析，将DOM数据与植物群落特性（如植物生物量生产或植物防御特性）以及与微生物相关的变量（如土壤微生物活性、生物量、群落结构和土壤微生物群和动物群的分类组成）联系起来。总之，这些方法将通过探索植物-微生物相互作用的分子信号，为加强BEF关系的机制提供新的见解。

It is generally accepted that the positive biodiversity-ecosystem functioning (BEF) relationship strengthens with time. This strengthening is supposed to be determined by i) the assembly of soil communities, such as microbial or faunal communities, and/or ii) the development of the plant communities. In both cases, interactions between plant communities and soil communities are altered. Most likely, these interactions and their alterations are mediated by the exchange of molecules. However, the question of how biodiversity affects the exchange of molecules and thus the mediation of interactions has rarely been considered in BEF research. Therefore, this project will analyse the interaction between plant and soil microbial communities and the soil matrix by using an advanced ultrahigh resolution mass spectrometric approach. We will analyse the molecular signatures of dissolved organic matter in order to better understand the positive BEF relationship in general and specifically its strengthening over time. We will compare the molecular signalling between plant communities and soil microbial communities that have different histories using a non-targeted approach of soil solution and soil extracts. Taking advantage of the Field Experiment, we will investigate the general effect of plant diversity on DOM composition under field conditions (WP1) and how it is affected by the soil history (WP2). The Ecotron Experiment, in which plants with different community histories are crossed with soils that have different histories, will enable us to assess the relative importance of plant vs. soil history on molecular DOM composition (WP3). Besides investigating the strengthening of the BEF relation over time on the basis of the molecular DOM composition, the temporal replicated DOM sampling in the Ecotron Experiment will allow to detect temporal shifts in the plant-microbe interaction. In close cooperation with the other subprojects, we will relate the DOM data to plant community properties, such as plant biomass production or plant defence traits, and to microbial-related variables like soil microbial activity, biomass, community structure and taxonomic composition of soil microbiota and fauna using uni- and multivariate statistics and network analyses. Together, these approaches will provide novel insights into the mechanisms of strengthening BEF relationships by exploring the molecular signals of plant-microbe interactions.