The role of arbuscular mycorrhizal fungi in plant litter decomposition

在气候变化的背景下，人们越来越关注影响土壤碳（C）循环和稳定的地下过程。土壤碳循环的一个关键组成部分是植物凋落物的分解，这可能受到微生物群落组成的强烈影响。最近，丛枝菌根真菌（AMF）对凋落物分解的影响受到了相当大的关注，但研究结果是模糊的，似乎取决于凋落物的质量和观察期的长度。此外，在微生物生物量或土壤基质中的C的稳定性在过去被忽视。由于植物凋落物是自然土壤固碳的主要来源，即使周转时间的微小变化也会产生全球性的重大影响。因此，我们的知识的循环和潜在的稳定的土壤碳是至关重要的理解和预测globalwarm.The本研究项目的目的是澄清模糊的作用AMF在植物凋落物分解。首先，我建议解开的机制，负责改变分解率在AMF的存在。这将通过一系列实验来实现，在这些实验中，我将测量根系和菌丝体的分泌物、土壤中养分含量和水分的变化以及参与分解的微生物群体的活动。其次，我建议测试AMF对凋落物分解的影响的一般性。为此，我将测量不同凋落物类型，AMF物种和土壤类型的凋落物分解。第三，我建议用实地实验来检验实验室结果的外部有效性。通过使用稳定同位素标记的植物凋落物，我将不仅跟踪凋落物的损失，而且还跟踪C在土壤中的命运和潜在的稳定性。该研究项目将有助于我们了解AMF共生的生态学和土壤碳循环的地下过程的知识。

In the context of climate change there is increasing interest in belowground processes that influence soil carbon (C) cycling and stabilization. One key component of soil C cycling is the decomposition of plant litter, which can be strongly influenced by the microbial community composition. Recently, the influence of arbuscular mycorrhizal fungi (AMF) on litter decomposition has received considerable attention, but findings are ambiguous and seem to depend on litter quality and the length of the observation period. Additionally, stabilization of C in microbial biomass or in the soil matrix have been neglected in the past. As plant litter represents the main source for natural soil carbon sequestration, even small changes in turnover time can have a globally significant impact. Therefore, our knowledge of the cycling and potential stabilization of soil carbon is crucial for understanding and predicting global warming.The aim of this research project is to clarify the ambiguous role of AMF in plant litter decomposition. First, I propose to unravel the mechanisms that are responsible for altered decomposition rates in the presence of AMF. This will be realized with a set of experiments in which I will measure root and mycelial exudates, changes in nutrient content and moisture in the soil and activity of microbial groups involved in decomposition. Second, I propose to test for the generality of AMF effects on litter decomposition. For this, I will measure litter decomposition across different litter types, AMF species and soil types. Third, I propose to test the external validity of the laboratory results with a field experiment. By using plant litter labelled with stable isotopes I will not only follow the loss of litter but also the fate and potential stabilization of C in the soil. This research project will contribute to our understanding of the ecology of the AMF symbiosis and our knowledge of belowground processes of soil C cycling.