The effect of land use intensity on biodiversity and functional role of biological soil crust communities with an emphasis on the biogeochemical cycling of carbon, nitrogen and phosphorus - CRUSTFUNCTION III

生物土壤结皮是微生物的生物多样性和活动热点，其作用是驱动养分(N，P)周转，稳定土壤表面。生物结壳具有复杂的群落网络，融合了不同生活方式的各种微生物。然而，生物壳的结构和功能的驱动因素相当未知，特别是在温带地区。因此，我们将沿着土地利用梯度调查生物多样性探索实验室不同林地中微生物(细菌、原生动物、真菌、藻类)的多样性及其在养分循环中的生物地球化学作用，了解土地利用强度和环境因素对生物壳的影响。中央组织的林地新扰动实验为研究生物壳的结构和功能提供了很好的机会，通过跟踪生物壳在强干扰后从初始阶段到成熟阶段的发展：一块去除原木的样地模拟了大片砍伐面积，这是一种广泛应用于森林采伐的方法；另一块保留了原木的地块，模拟了暴风雨后的自然树木倒下，这是由于气候变化而在德国更有可能发生的极端事件。我们将通过实地、分析和分子相结合的定期检查(生物量、养分、土壤有机质、微生物区系)的定期检查(生物量、养分、土壤有机质、微生物区系)，在两年多的时间里跟踪这些试验点从年轻到成熟阶段的生物壳的结构和功能。我们还将参与联合土壤采样活动，走访所有150个森林样地和生物结壳样本。我们将量化生物结壳中的微生物生物量，通过高通量测序/元基因组学确定其群落结构，并使用成熟的qPCR方法将这些结果与N的养分周转和研究较少的P循环联系起来。为了识别和可视化高空间分辨率的营养循环中的关键角色，我们将进行应用稳定同位素探测和NanoSIMS的实验室实验。获得的生物多样性和功能基因组数据将与生物壳的营养状况相联系，C、N和P的浓度和最重要的化学物种将被量化。稳定同位素的实验室实验将导致对养分循环的关键因素及其空间异质性的基本理解。最后，这使得第一次能够重建生物壳中主要营养循环和微生物相互作用的定性和定量模式，以响应土地利用强度和干扰。所获得的数据将被整合到生物多样性探索实验室的联合土壤网络中，并将成为一项综合建议的核心，该建议旨在定性和定量地将生物结壳的性能与土壤中的其他微生物热点(根际/根际)进行比较。

Biological soil crusts (biocrusts) are microbial biodiversity and activity hotspots acting as “ecosystem-engineers” that drive nutrient (N, P) turnover and stabilize soil surfaces. Biocrusts are characterized by complex community networks integrating various microorganisms with different life styles. However, drivers for the structure and function of biocrusts are fairly unknown, in particular in temperate regions. Thus, we will investigate diversity of biocrust microorganisms (bacteria, protists, fungi, algae) and their biogeochemical role in nutrient cycling in different forest plots of the Biodiversity Exploratories along a land use gradient, and understand how biocrusts are influenced by land use intensity and environmental factors.The centrally organized new disturbance experiment in forest plots offers great opportunity to study the structure and function of biocrusts by following their development from initial to mature stages after strong disturbance: one plot with the removed logs simulates a large clear-cut area, a widely applied method in forest-harvesting; the other plot, where the logs remain, simulates natural tree fall after a storm, extreme events that become more likely in Germany due to climate change. We will follow the structure and function of biocrusts at these experimental sites from young to mature stages over two years by regular inspection (biocrust areal coverage) and sampling (biomass, nutrients, soil organic matter, microbiota) using a combination of field, analytical and molecular methods. We will also participate in the joint soil sampling campaign, visit all 150 forest plots and sample biocrusts.We will quantify the microbial biomass in biocrusts, identify their community structure by high-throughput-sequencing/metagenomics, and link these results to the nutrient turnover of N and the poorly studied P-cycle by using a well-established qPCR approach. To identify and visualize key players with high spatial resolution in the nutrient cycling, we will conduct a lab experiment applying stable isotope probing and NanoSims. The obtained data on biodiversity and functional genomic will be linked to the nutrient status of the biocrusts, for which concentrations and most important chemical species of C, N and P will be quantified. The lab experiment with stable isotopes will lead to a fundamental understanding on the key players of nutrient cycling and their spatial heterogeneity. Finally, this allows for the first time the reconstruction of qualitative and quantitative major nutrient cycles and microbial interaction patterns in biocrusts in response to land use intensity and disturbance. The obtained data will be integrated into the joint soil network in the Biodiversity Exploratories, and will be the nucleus for a synthesis proposal, which aims to qualitatively and quantitatively compare the performance of biocrusts with other microbial hotspots in soils (detitrus-/rhizosphere).