Nutrient Dynamics in Soil and Soil Water impact Arbuscular Mycorrhizal Fungi (AMF) Colonization and Abundance on Grassland Slopes in Eastern Bavaria, Germany

It is widely known that natural soils under different land use provide a heterogenous environment regarding nutrient availability. This affects plants as well as microorganisms such as arbuscular mycorrhizal fungi (AMF).  It can have an impact on the abundance and amount of root colonization by AMF. These complex systems are often studied in experimental setups, while the wider scope of natural systems shaping entire landscapes so far received less attention.

To unravel the impact of land use and the soil parent material (including the typical periglacial layering along slopes in the area) on nutrient availability and thus AMF root colonization and total abundance, two forest-grassland-creek catenae were selected in the low mountain region of the eastern Bavarian Forest (Germany). This landscape is characterized by the uniformity of the bedrock and its weathering product (saprolite), which decisively shapes the landscape. One of the two catenae was extensively used for feed production with 2-3 cuts per year. It received slurry twice a year as well as carbonic magnesium lime. The other catena had always been used as part of a deer browsing area with low stocking density. It has never been fertilized (apart from deer excretions) or limed and is mulched once per year. Soil profiles along both catenae were sampled and suction cups placed according to the periglacial layering, to investigate the nutrients in percolation- and interflow water coming downslope. Moreover, samples were taken for the investigation of AMF colonization and abundance according to the catena-profiles.

We will present our results on the nutrient dynamics observation along the two catenae. These consist of nutrient concentrations in slope water from the suction cups as well as carbon, nitrogen and phosphorus contents along the catenae. Moreover, we will show the corresponding AMF root colonization and AMF abundance data. We expect these data to show a correlation of nutrient dynamics along the slope with AMF colonization and abundance as well as a difference between the two sites in nutrient dynamics and resulting AMF occurrence, according to the divergent land use.

To summarize, we will provide a field-based observation of the impact of land use regimes and landscape-shaping geological disposition on nutrient dynamics along grassland slopes in the Bavarian Forest, which influence AMF colonization and abundance.