Mineral surfaces as hotspots for microbes and element cycling in the Biodiversity Exploratories

土壤中有机质（OM）的稳定和养分保持是由它们与矿物质表面的相互作用决定的。在矿物上，活性表面与微生物生命相遇，形成所谓的矿物圈，其特征是强烈而复杂的生物和非生物相互作用。微生物定植与有机物和营养物质的吸收和释放的相互作用导致矿物圈内的持续变化和转化，对土壤中的碳和营养物质的储存和有效性产生直接影响。这些发展对环境和生态系统条件的响应轨迹很难理解。拟议的项目将利用独特的机会，研究自2015年以来在生物多样性探索的所有实验地块暴露于环境土壤条件下的原始矿物样本（粘土矿物伊利石和氧化铁针铁矿）。我们的目标是通过协调、跨学科的方法，探索与矿物相关的微生物群落、有机物和营养物质在土地利用和生物多样性驱动下的共同发生。经过五年的暴露时间后，我们将对矿物圆筒以及周围的土壤进行取样。这些将用一套互补的、精心挑选的最先进的表面敏感、生物地球化学、同位素、矿物学和微生物学方法进行分析。我们假设土地利用的类型和强度和生物多样性影响：(1)矿物伴生有机质的积累和质量，(2)植物和微生物来源对矿物伴生有机质的贡献，(3)矿物圈中出现的微生物群落模式，(4)矿物伴生有机质的保存机制，(5)矿物圈中营养物质的积累，(6)矿物圈土壤深度相关差异。这种合作方法将首次允许深入了解在自然环境条件下开发矿物球。

The stabilization of organic matter (OM) and nutrient retention in soils is determined by their interactions with minerals surfaces. On minerals, reactive surfaces meet with microbial life to form the so-called mineralosphere, which is characterized by intense and complex biotic and abiotic interactions. The interplay of microbial colonization, and sorption and release of organic matter and nutrients cause continuous changes and transformations within the mineralosphere, with immediate consequences for carbon and nutrient storage and availability in soil. The trajectories of these developments in response to environmental and ecosystem conditions are hardly understood. The proposed project will take the unique opportunity of studying pristine mineral samples (illite, a clay mineral, and goethite, an iron oxide) being exposed to ambient soil conditions at all experimental plots of the Biodiversity Exploratories since 2015. We aim at exploring the co-occurrence of mineral-associated microbial communities, organic matter, and nutrients as driven by land use and biodiversity in a coordinated, interdisciplinary approach. After an exposure time of five years we will sample mineral cyclinders as well as surrounding soils. These will be analyzed with a suite of complementary, carefully selected state-of-the-art surface-sensitive, biogeochemical, isotopic, mineralogical, and microbiological methods. We hypothesize that type and intensity of land use and biodiversity affect: (1) the accumulation and quality of mineral-associated organic matter, (2) the contribution of plant and microbial sources to mineral-associated organic matter, (3) the patterns of microbial communities emerging in the mineralosphere, (4) the preservation mechanisms of mineral-associated organic matter, (5) the nutrient accumulation in the mineralosphere, and (6) the soil depth-related differences in mineralosphere. This collaborative approach will allow for the first time in-depth insight into developing mineralospheres under natural environmental conditions.