Nematodes as link between microbial and faunal food web

拟议的项目在“长期顽固性碳输入”和“通过食草动物和碎屑食物链的碳流”两个实地实验中考察了线虫动物群。研究了从资源丰富到低营养生境的梯度，即从高多样性到低多样性的食物网。评估了资源的可用性和质量（顽固性与不稳定性）以及存在或不存在活植物（根际与腐殖层）对线虫种群的影响。应用线虫区系分析概念，基于丰度、结构和通道指数，深入了解微食物网结构。在实验室模型系统中，确定了耕地中优势分类群的细菌/真菌及其线虫食草动物之间食物网链接的碳通量速率。此外，还研究了草食线虫诱导植物根系碳泄漏作为根与细菌能量通道之间的联系。通过13C/12C稳定同位素探测（FA-SIP），脂肪酸是主要的碳货币。将线虫田间种群的定性和定量数据与微生物和食草动物中生物标志物脂肪酸的碳流相结合，将有助于连接微生物和动物性食物网，并将线虫功能群与土壤碳循环中的特定过程直接联系起来。

The proposed project examines the nematode fauna at the two field experiments “Long-term recalcitrant C input” and “Carbon flow via the herbivore and detrital food chain”. A gradient from resource rich to deeper oligotrophe habitats, i.e. from high to low diverse food webs, is investigated. The impact of resource availability and quality (recalcitrant versus labile) and presence or absence of living plants (rhizosphere versus detritusphere) on the nematode population are assessed. Insight into micro-food web structure is gained by application of the nematode faunal analysis concept, based on the enrichment, structure and channel index. In laboratory model systems carbon flux rates for food web links are determined between bacteria/fungi and their nematode grazers for dominant taxa in the arable field. Further, carbon leakage from plant roots induced by herbivore nematode is studied as link between root and bacterial energy channels. By using 13C/12C stable isotope probing (FA-SIP) fatty acids serve as major carbon currency. Coupling qualitative and quantitative data on nematode field populations, with carbon flow via biomarker fatty acids in microorganisms and grazers will allow to connect microbial and faunal food web, and to directly link nematode functional groups with specific processes in the soil carbon cycle.