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Reduction in land-use intensity may favour plant-symbiont interactions, modifying nutrient acquisition strategies of plants and microbes at different scales. At the rhizosphere scale, for example, a narrow region of soil directly influenced by root secretions and associated soil microorganisms, the root-soil interface is characterised by gradients of nutrients, protons, carbon resources, and living microorganisms. The hyphosphere is defined as a sphere where symbiotic and non-symbiotic fungi are present in the soil environment; it is characterised by intense fungal-bacterial-soil. These distinct zones are often difficult to separate experimentally from each other.


The aim of our study is to unveil how fungal-bacterial interactions in the hyphosphere contribute to plant nutrition, as well as how the carbon supply from plants affect bacteria via the symbiotic interactions with fungi.

In the next three years, we will test the following hypotheses:

  1. Both symbiotic fungi (mycorrhizal fungi) and free-living saprotrophic fungi dominate initial microbial carbon uptake from the plant by rapid processing and channelling of rhizodeposits into the hyphosphere, wherefore this can function as a ‘carbon bridge’ between plants and bacteria; bacteria profit as secondary consumers.
  2. Plants rely on nutrient transport via the hyphosphere to a greater extent in low as compared to high land-use intensity (LUI) grassland soils.
  3. Experimental de-intensification of grassland land use will modify abundance and function of soil microorganisms either by reducing nutrient supply (reduced fertilisation, direct response of soil microorganisms) or by reducing mowing intensity (changing plant input into soils, indirect response of soil microorganisms).

In order to test our hypotheses, we will need a complete separation between the rhizosphere and the hyphosphere. We will use newly developed HYPHOboxes that experimentally separate the hyphosphere from the rhizosphere and the surrounding bulk soil (Fig. 1).

Fig. 1. HYPHObox compartments. a. HYPHObox schema, b. HYPHObox compartments with different meshes and c. HYPHObox as seen from the side of the rhizosphere compartment.


Experiments 1 and 2: Carbon flow from plants to the hyphosphere and nutrient flow from the hyphosphere to the plants and back

The goals of these experiments are to understand (i) which fungi benefit most from plant-derived carbon in grassland ecosystems and which fungi are responsible for the ‘long-distance’ transport (>15 mm) of carbon, thereby providing resources for bacteria as secondary consumers (Fig. 2a), and (ii) which fungi are responsible for the transport 13C and 15N from the detritusphere through the hyphosphere to the rhizosphere (Fig. 2b). We will use a 13CO2 pulse labelling approach to quantify the carbon flux of plant-fixed C into fungi and their associated bacteria, and a 13C and 15N labelling in the detritusphere compartment will allow us to measure long-term 13C and 15N incorporation in the microbial biomass as well as its transfer to the plant biomass.

Fig. 2. Experimental design of the first and second experiments: a) 13CO2 labelling of plants and 15N labelling in the detritusphere compartment will allow us to measure short-term 13C incorporation in the microbial biomass as well as 15N incorporation in the plant biomass; b) 13C and 15N labelling in the detritusphere compartment will allow us to measure long-term 13C and 15N incorporation in the microbial biomass as well as its transfer to the plant biomass.


Experiment 3: De-intensification of grassland sites – Direct versus indirect effects on soil microorganisms (multi-grassland land-use experiments)

De-intensification of land use may drive changes in microbial communities and in the soil functions they regulate. The newly established multi-grassland land-use experiments (Fig. 3) will make it possible to identify the direct and indirect mechanisms that may contribute to changes in microbial abundance and function.


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Einfluss der Landnutzungsintensität auf die mikrobielle Bio-masse von Grünlandböden
Bauer C. (2018): Einfluss der Landnutzungsintensität auf die mikrobielle Bio-masse von Grünlandböden. Bachelor thesis, University Hohenheim
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Die Landnutzungsintensität verändert die räumliche Verteilung und Funktion von Bodenmikroorganismen im Grünland
Berner D., Marhan S., Keil D., Schützenmeister A., Piepho H.-P., Poll C., Kandeler E. (2010): Land-Use Intensity Modifies Spatial Distribution and Function of Soil Microorganisms in Grasslands. Pedobiologia 54 (5-6), 341-351. doi:10.1016/j.pedobi.2011.08.001
More information:  doi.org
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Impact of soil disturbance on microorganisms in differently managed grassland soils linked to the ecosystem resilience
Binder I. (2016): Impact of soil disturbance on microorganisms in differently managed grassland soils linked to the ecosystem resilience. Master thesis, University Hohenheim
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Räumliche und zeitliche Variationen von Mikroorganismen in Grünlandböden - Einflüsse von Landnutzungsintensität, Pflanzen und Bodeneigenschaften
Boeddinghaus R. S. (2019): Spatial and temporal variations of microorganisms in grassland soils - influences of land-use intensity, plants and soil properties. Dissertation, University Hohenheim
More information:  opus.uni-hohenheim.de
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Veränderungen von funktionellen Pflanzeneigenschaften erklären parallele Veränderungen in der Struktur und Funktion mikrobieller Gemeinschaften in Grünlandböden
Boeddinghaus R. S., Marhan S., Berner D., Boch S., Fischer M., Hölzel N., Kattge J., Klaus V. H., Kleinebecker T., Oelmann Y., Prati D., Schäfer D., Schöning I., Schrumpf M., Sorkau E., Kandeler E., Manning P. (2019): Plant functional trait shifts explain concurrent changes in the structure and function of grassland soil microbial communities. Journal of Ecology 107 (5), 2197-2210. doi: 10.1111/1365-2745.13182
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Boeddinghaus R. S., Marhan S., Gebala A., Haslwimmer H., Vieira S., Sikorski J., Overmann J., Soares M., Rousk J., Rennert T., Kandeler E. (2021): The Mineralosphere – Interactive zone for microbial colonization and carbon use in grassland soils. Biology and Fertility of Soils 57, 587–601. doi: 10.1007/s00374-021-01551-7
More information:  doi.org
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Gibt es allgemeine räumliche Verteilungsmuster von mikrobieller Biomasse und Enzymaktivitäten in Grünlandböden?
Boeddinghaus R. S., Nunan N., Berner D., Marhan S., Kandeler E. (2015): Do general spatial relationships for microbial biomass and soil enzyme activities exist in temperate grassland soils? Soil Biology & Biochemistry 88, 430-440. doi: 10.1016/j.soilbio.2015.05.026
More information:  doi.org
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Einfluss der Landnutzungsintensität auf die mikrobielle Biomasse und Enzymaktivitäten im Rhizosphärenboden verschiedener Grünlandpflanzenarten
Boob M. (2015): Einfluss der Landnutzungsintensität auf die mikrobielle Biomasse und Enzymaktivitäten im Rhizosphärenboden verschiedener Grünlandpflanzenarten. Master thesis, Universität Hohenheim
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Einfluss von Landnutzungsintensität auf Mikroorganismen in Grünlandböden der Schwäbischen Alb
Breuer B.S. (2008): Einfluss von Landnutzungsintensität auf Mikroorganismen in Grünlandböden der Schwäbischen Alb. Bachelor Thesis, University Hohenheim
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Fiore-Donno A. M., Richter-Heitmann T., Degrune F., Dumack K., Regan K. M., Mahran S., Boeddinghaus R. S., Rillig M. C., Friedrich M. W., Kandeler E., Bonkowski M. (2019): Functional Traits and Spatio-Temporal Structure of a Major Group of Soil Protists (Rhizaria: Cercozoa) in a Temperate Grassland. Frontiers in Microbiology 10:1654. doi: 10.3389/fmicb.2019.01654
More information:  doi.org
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Räumliche Heterogenität mikrobieller Enzymaktivitäten in Grünlandböden der Schwäbischen Alb
Glatzle S.(2008): Räumliche Heterogenität mikrobieller Enzymaktivitäten in Grünlandböden der Schwäbischen Alb. Bachelor thesis, University Hohenheim
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Goldmann K., Boeddinghaus R. S., Klemmer S., Regan K. M., Heintz-Buschart A., Fischer M., Prati D., Piepho H.-P., Berner D., Marhan S., Kandeler E., Buscot F., Wubet T. (2020): Unraveling spatio‐temporal variability of arbuscular mycorrhiza fungi in a temperate grassland plot. Environmental Microbiology 22 (3), 873-888. doi: 10.1111/1462-2920.14653
More information:  doi.org
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Die Mineralosphäre – Sukzession und Physiologie von Bakterien und Pilzen während der Besiedlung reiner Minerale in Grünlandböden mit unterschiedlicher Landnutzungsintensität
Kandeler E., Gebala A., Boeddinghaus R. S., Müller K., Rennert T., Soares M., Rousk J., Marhan S. (2019): The mineralosphere – Succession and physiology of bacteria and fungi colonising pristine minerals in grassland soils under different land-use intensities. Soil Biology and Biochemistry 136: 107534. doi: 10.1016/j.soilbio.2019.107534
More information:  doi.org
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Einfluss von Landnutzung auf Abundanz, Funktion und räumliche Verteilung von N-umsetzenden Mikroorganismen in Grünlandböden
Keil D. (2015): Influence of land use on abundance, function and spatial distribution of N-cycling microorganisms in grassland soils. Dissertation, University of Hohenheim
More information:  opus.uni-hohenheim.de
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Einfluss von Landnutzungsintensität auf die räumliche Verteilung Stickstoff umsetzender Mikroorganismen in Grünlandböden
Keil D., Meyer A., Berner D., Poll A., Schützenmeister A., Piepho H.-P., Vlasenko A., Philippot L., Schloter M., Kandeler E., Marhan S. (2011): Influence of land-use intensity on spatial distribution of N-cycling microorganisms in grassland soils . FEMS Microbiology Ecology 77 (1), 95-106. doi: 10.1111/j.1574-6941.2011.01091.x
More information:  doi.org
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Einfluss von Temperaturerhöhung und Dürre auf Lachgasemissionen und die Häufigkeit von denitrifizierenden Bakterien in Grünlandböden mit unterschiedlicher Landnutzungsintensität
Keil D., Niklaus P. A., von Riedmatten L. R., Boeddinghaus R. S., Dormann K. F., Scherer-Lorenzen M., Kandeler E., Marhan S. (2015): Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land use. FEMS Microbiology Ecology 91(7), pii: fiv066. doi: 10.1093/femsec/fiv066
More information:  doi.org
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Long-term effects of disturbance and seed addition on soil microbial biomass in grassland with high and low land-use intensity
Langzeit Effect von Störung und Ansaat auf die mikrobielle Biomasse in Grünlandböden mit hoher und niedriger Landnutzungsintensität
Lang K. (2018): Long-term effects of disturbance and seed addition on soil microbial biomass in grassland with high and low land-use intensity. Bachelor thesis, University Hohenheim
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Eine neue Methode (midDRIFTS basierte Spektroskopie) erlaubt die schnelle und kostengünstige Vorhersage von mikrobieller Biomasse und Aktivität in Grünlandböden
Rasche F., Marhan S., Berner D., Keil D., Kandeler E., Cadisch G. (2013): midDRIFTS-based partial least square regression analysis allows predicting microbial biomass, enzyme activities and 16S rRNA gene abundance in soils of temperate grasslands. Soil Biology and Biochemistry 57, 504–512. doi: 10.1016/j.soilbio.2012.09.030
More information:  doi.org
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Regan K. M. (2016): Linking Microbial Abundance and Function to Understand Nitrogen Cycling in Grassland Soils. Dissertation, University Hohenheim
More information:  opus.uni-hohenheim.de
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Zeigen Pflanzen oder abiotische Bodeneigenschaften saisonal bedingt mehr Einfluss auf die Verteilung von Mikroorganismen in Grünlandböden?
Regan K. M., Nunan N., Boeddinghaus R. S., Baumgarten V., Berner D., Boch S., Oelmann Y., Overmann J., Prati D., Schloter M., Schmitt B., Sorkau E., Steffens M., Kandeler E., Marhan S. (2014): Seasonal controls on grassland microbial biogeography: Are they governed by plants, abiotic properties or both? Soil Biology and Biochemistry 71, 21–30. doi: 10.1016/j.soilbio.2013.12.024
More information:  doi.org
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Regan K., Stempfhuber B., Schloter M., Rasche F., Prati D., Philippot L., Boeddinghaus R. S., Kandeler E., Marhan S. (2017): Spatial and temporal dynamics of nitrogen fixing, nitrifying and denitrifying microbes in an unfertilized grassland soil. Soil Biology and Biochemistry 109, 214–226. doi: 10.1016/j.soilbio.2016.11.011
More information:  doi.org
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Richter-Heitmann T., Hofner B., Krah F.-S., Sikorski J., Wüst P. K., Bunk B., Huang S., Regan K., Berner D., Boeddinghaus R. S., Marhan S., Prati D., Kandeler E., Overmann J., Friedrich M. W. (2020): Stochastic dispersal rather than deterministic selection explains the spatio-temporal distribution of soil bacteria in a temperate grassland. Frontiers in Microbiology 11: 1391. doi: 10.3389/fmicb.2020.01391
More information:  doi.org
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Die potentielle Methan-Oxidation des Bodens in Abhängigkeit von der Landnutzungsintensität am Beispiel von Grünland und Wald
Rohrbach K. (2017): Die potentielle Methan-Oxidation des Bodens in Abhängigkeit von der Landnutzungsintensität am Beispiel von Grünland und Wald. Bachelor thesis, University Hohenheim
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Erholung von Ökosystemfunktionen nach experimenteller Störung in 73 Grünlandflächen mit unterschiedlicher Landnutzungsintensität, Artenvielfalt und Zusammensetzung der Pflanzengesellschaft
Schäfer D., Klaus V. H., Kleinebecker T., Boeddinghaus R. S., Hinderling J., Kandeler E., Marhan S., Nowak S., Sonnemann I., Wurst S., Fischer M., Hölzel N., Hamer U., Prati D. (2019): Recovery of ecosystem functions after experimental disturbance in 73 grasslands differing in land‐use intensity, plant species richness and community composition. Journal of Ecology 107 (6), 2635-2649. doi: 10.1111/1365-2745.13211
More information:  doi.org
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Lineare gemischte Modelle und Geostatistik für geplante Experimente in den Bodenwissenschaften – zwei unversöhnliche Methoden oder zwei Seiten derselben Medaille
Slaets J., Boeddinghaus R. S., Piepho H.-P. (2021): Linear mixed models and geostatistics for designed experiments in soil science ‐ two entirely different methods or two sides of the same coin? European Journal of Soil Science 72 (1), 47-68. doi: 10.1111/ejss.12976
More information:  doi.org
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Nach welchen Regeln besiedeln Bakterien den Boden?
Vieira S., Sikorski J., Gebala A., Boeddinghaus R. S., Marhan S., Rennert T., Kandeler E., Overmann J. (2020): Bacterial colonization of minerals in grassland soils is selective and highly dynamic. Environmental Microbiology 22 (3), 917-933. doi: 10.1111/1462-2920.14751
More information:  doi.org

Project in other funding periods

SCALEMIC (Contributing project)
#Microorganisms & Fungi  #2008 – 2011  #Soil microorganisms […]
SCALEMIC (Contributing project)
#Microorganisms & Fungi  #2011 – 2014  #Soil microorganisms […]
SCALEMIC (Contributing project)
#Microorganisms & Fungi  #2014 – 2017  #Soil microorganisms […]

Scientific assistants

Prof. Dr. Ellen Kandeler
Project manager
Prof. Dr. Ellen Kandeler
Universität Hohenheim
Dr. Sven Marhan
Project manager
Dr. Sven Marhan
Universität Hohenheim
Dr. Anna Abrahao
Employee
Dr. Anna Abrahao
Universität Hohenheim
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