Structure and function of biocrusts in weathering, soil formation and erosion processes (CRUSTWEATHERING).

在全球范围内，生物土壤结皮(生物结壳)构成了干旱地区地球--关键地带--最具生产力的微生物生物量。生物结壳是由异养细菌、真菌、地衣、苔藓、蓝藻和藻类及其副产品等生物及其副产品形成的，形成了由有机材料结合在一起的无机颗粒的表层土壤。它们可以被描述为生态系统工程师，形成水稳定的聚集表层，在初级生产、矿化、生物风化、尘埃捕获以及土壤、斜坡和整个景观的稳定方面具有重要的多功能生态作用，从而影响不同规模的养分和水文循环。密集的文献审查使我们意识到，这些社区在南美洲几乎没有被研究过，尽管在优先方案的研究领域非常丰富。因此，这项跨学科建议的目标是：1)使用野外和实验室相结合的方法来评估智利生物群落类型几乎未知的群落结构，以解决整个生物群落生物群落的相对丰富度，特别是关于它们在风化和景观形成过程中的作用(谁在做什么？)；2)揭示哪些丰富的生物通过哪些生化过程对生物风化做出贡献，并量化与群落结构和环境条件相关的反应速率；3)揭示生物结壳在P-(特别强调！)、C-和N-化合物的耦合生物地球化学循环中的作用；从原子/分子、单矿物颗粒、生物结壳斑块和土壤剖面到坡度/集水区尺度，后者借助遥感光谱数据和共同开发的传递函数；4)了解小气候条件和水可获得性如何决定干旱生态系统中生物结壳群落的结构和活动、覆盖及其功能。这项研究将从土壤学、地球植物学和自然地理现场描述、观测地块仪器以及生物化石和土壤采样的联合实地运动开始。先进的方法包括最新的分子生物学、电子显微镜、植物生理、化学分析(基于质量和同步加速器的光谱)和遥感技术，以及相应的多变量数据评估方法。预期的结果不仅将揭示目前未知的生物及其生理和生态功能，而且还将启发它们对生物风化和基本地球形成过程的贡献，并为区域或全球尺度的地球系统模型提供全面的知识和数据背景。

On a global scale, biological soil crusts (biocrusts) form the most productive microbial biomass of the Earth´ -Critical Zone- in arid regions. Biocrusts are formed by living organisms such as heterotrophic bacteria, fungi, lichens, bryophytes, cyanobacteria and algae and their by-products, creating a top-soil layer of inorganic particles bound together by organic materials. They can be characterized as ecosystem-engineers forming water-stable, aggregated surface layers that have important multi-functional ecological roles in primary production, mineralization, bioweathering, dust trapping, and the stabilization of soils, slopes and entire landscapes, thereby affecting the nutrient and hydrological cycles across scales. Intensive literature reviews made us aware, that these communities are almost unstudied in South America, although highly abundant in the study areas of the Priority Programme. Therefore, the objectives of this interdisciplinary proposal are to 1) evaluate the almost unknown community structure of Chilean biocrust types using a combination of field and laboratory methods to address the relative abundance of the full spectrum of biocrust organisms, particularly with regard to their role in weathering and landscape forming processes (who is doing what?); 2) disclose which of the abundant organisms contribute by which biochemical processes to bioweathering, and quantify the reaction rates in relation to community structure and environmental conditions; 3) uncover the function of biocrusts in the coupled biogeochemical cycling of P- (particular emphasis!), C- and N-compounds across spatial scales from the atomic/molecular-, the single mineral grain-, biocrust patch- and soil profile- up to the slope/catchment-scale, the latter with the help of remotely sensed spectral data and jointly developed transfer functions; 4) understand how microclimatic conditions and water availability determine the biocrust community structure and activity, coverage and their functioning in the arid ecosystems. The research will start with a joint field campaign for pedological, geobotanical and physical-geographical site descriptions, observation plot instrumentation, and biocrust and soil samplings. The advanced methodological approaches involve the latest molecular-biological, electron-microscopic, plant physiological, chemical-analytical (mass- and synchrotron-based spectroscopies) and remote sensing techniques, and the corresponding multivariate data evaluation methods. The expected results will not only disclose presently unknown biocrust organisms and their physiological and ecological functioning but also enlighten their contribution to bioweathering and fundamental Earth-shaping processes, and provide overall knowledge and data background for regional or global-scale geosystem models.