The function of the hyphosphere in carbon and nutrient partitioning between plants and microorganisms in grassland soils under different land-use intensities

草地土壤微生境尺度上的过程可以解释大尺度上生态系统功能的变化。在最后阶段，我们证明了真菌是草地土壤矿层和根际之间碳和养分的重要传递者。在下一阶段，我们希望利用新开发的菌丝盒阐明菌丝周围无根土壤在田间条件下的特殊重要性。我们将把根际和碎屑层与根际区分开。采用两种13c标记方法，一种是标记CO2，另一种是标记植物残留物，我们将分别测试土地利用强度（LUI）是否影响植物从根际和根际的碳流，以及从根际到根际的养分流。问题是，互惠的丛枝菌根（AMF）或自由生活的腐养真菌是否会通过加工和快速将根沉积物输送到菌丝圈来主导最初的碳吸收。根际微生物也可以作为腐殖层和根际之间的碳和营养桥梁。新建立的多草地土地利用试验将使我们有机会研究草地土地利用去集约化对土壤微生物生物量和功能的影响程度和速度。养分供应的减少（减少施肥，土壤微生物的直接响应）或刈割强度的降低（植物对土壤的投入变化，土壤微生物的间接响应）将使我们能够解开这两种不同的机制，并将提高我们对草地农业生态系统对土地利用强度变化响应的机制理解。对150个草地地点的土壤微生物特性进行长期监测（延续2011年、2014年和2017年），将使我们能够将土地利用强度的短期变化（超过3年）与这些地点对微生物群落功能和组成的长期历史（遗留效应）区分开来。

Processes at the micro-habitat scale in grassland soils may explain changes in ecosystem functions at larger scales. In the last phase we demonstrated that fungi are important transmitters of carbon and nutrients between the mineralosphere and the rhizosphere in grassland soils. In the next phase we want to elucidate the specific importance of the hyphosphere (root-free soil around hyphae) under field conditions using newly developed HYPHOboxes. We will separate the rhizosphere and detritusphere from the hyphosphere. Using two 13C-labelling approaches, one with labelled CO2, the other with labelled plant residues, we will test whether land-use intensity (LUI) influences carbon flow from plants into the rhizo- and hyphospheres, and nutrient flow from the hyphosphere into the rhizosphere, respectively. The question is whether mutualistic arbuscular mycorrhizal (AMF) or free-living saprotrophic fungi will dominate the initial C uptake by processing and rapid channelling of rhizodeposits into the hyphosphere. Hyphosphere microorganisms may also act as carbon and nutrient bridges between the detritusphere and the rhizosphere. The newly established multi-grassland land-use experiments will give us the opportunity to investigate to what degree and how quickly de-intensification of grassland land-use will modify biomass and function of soil microorganisms. The reduction in nutrient supply (reduction of fertilization, direct response of soil microorganisms) or the reduced mowing intensity (changes in plant input into soils, indirect response of soil microorganisms) will allow us to disentangle the two different mechanisms and will improve our mechanistic understanding of the response of grassland agroecosystems to changes in land-use intensity. Long-term monitoring of soil microbial properties in 150 grassland sites (in continuation of 2011, 2014 and 2017) will enable us to disentangle short-term changes (over three years) in land-use intensity from longer-term history of the sites (legacy effects) on the functioning and composition of microbial communities.