SSS4.5 | From fungi to fauna: functions, interactions and biodiversity that shape soils
From fungi to fauna: functions, interactions and biodiversity that shape soils
Convener: Erik Verbruggen | Co-conveners: Tullia CalogiuriECSECS, Gerrit AngstECSECS, Elly MorriënECSECS, Emilia Hannula, Dimitrios Floudas, Edith HammerECSECS
| Thu, 27 Apr, 08:30–10:15 (CEST)
Room 0.96/97
Posters on site
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
Hall X3
Orals |
Thu, 08:30
Thu, 10:45
Soil is the habitat for a myriad of organisms. These include soil fungi and fauna who are crucial in providing soil related ecosystem services, often through their interaction with microorganisms and plants. Soil fungi and fauna are key agents in litter decomposition, soil organic matter formation, and soil structure formation.
The polarized, network forming growth of fungi, their diverse ecological roles such as mutualistic interactions with plants, and unique suites of metabolic activities make them important players for many soil ecosystem functions.
The activity of soil fauna can result in the production of decomposition by-products which are still poorly chemically and physically characterized, despite the fact that they are a springboard for soil organic matter formation as well as a potential source of nutrients.
In this session, we cover a wide range of topics related to the effect of soil fungi and fauna on biogeochemical cycling (e.g., organic carbon storage, nutrient availability, gas emissions) in interaction with soil properties (e.g., aggregation, bioturbation, biopores, weathering), biodiversity relationships, and trophic interactions. These include studies on the effect of soil fungi and fauna on litter decomposition and the analyses of the decomposition by-products, as well as studies that explicitly tackle the interactions between soil fauna, plants, fungi, and other microorganisms.
Contributions cover the changing role of soil fauna and fungi under climate and land use changes and how this affects sustainable soil fertility.

Orals: Thu, 27 Apr | Room 0.96/97

Chairpersons: Erik Verbruggen, Gerrit Angst, Tullia Calogiuri
On-site presentation
Elisa Pellegrino, Gaia Piazza, Blessing Mhlanga, Myriam Arcidiacono, Christian Thierfelder, Marco Nuti, and Laura Ercoli

Agricultural production in regions such as sub-Saharan Africa (SSA) is very low as compared to other regions such as the Mediterranean area (MED). Differences are mainly due to agricultural input use which is generally lower in SSA. Indeed, in both regions, where unsustainable agricultural practices are largely applied although varying in intensification, soil organic carbon degradation and soil biodiversity decline are widespread issues. However, whether changes of soil microbial diversity have consequences on agroecosystem services, like crop productivity, in such agro-ecological zones is still scarcely investigated at field level. This long-term field study aimed to understand how different agricultural practices, such as conservation agriculture (CA)-based systems, affect soil microbiome (i.e., arbuscular mycorrhizal fungi (AMF) and bacteria) and their implications on crop productivity. We selected two contrasting soils and agro-ecological zones, in Italy (Centre of Agro-Environmental Research “Enrico Avanzi” – CiRAA – in Pisa) and in Zambia (Msekera Research Station – MRS – in Chipata), to investigate the responses of AMF and bacterial community to CA practices. The experiment at CiRAA was started in 1993 on a silt loam soil and was set up as a split plot design to test tillage regime as the main plot factor and nitrogen (N) fertilization rate as the sub-plot factor. Tillage regimes were conventional tillage (CT) and minimum tillage (MT), while the N fertilization rates were no fertilization (N0) and fertilized with 200 kg N ha-1 split into three applications (N200). For all treatments, wheat (Triticum aestivum L.) was rotated with soybean (Glycine max L.) in one-year rotations. The experiment at MRS was started in 2012 on a sandy clay loam soil and tested three treatments: CT and maize (Zea mays L.) as sole crop, no-tillage plus mulch (NT+M), and no-tillage plus mulch and rotation (NT+M+R) with maize in rotation with soybean. The climate is cold humid Mediterranean (Csa) at CiRAA and warm temperate with dry winters and hot summers (Cwa) at MRS. DNA was extracted from soil: for AMF PCRs were carried out amplifying part of the SSU, ITS1, 5.8S, ITS2 and part of the LSU of the 18S rRNA region, while for bacteria PCRs were carried out amplifying the V3 and V4 regions of the 16S rRNA region. AMF were characterized by a cloning and Sanger sequencing approach (ca. 1700 bp), whereas bacteria by an Illumina sequencing approach (ca. 630 bp). In both zones, AMF and bacterial composition was similar among CA systems, whereas the long-term implementation of the CA systems resulted in more diverse microbial communities across the agro-ecological zones. CA systems led to positive interactions between AMF and bacterial communities and more complex soil microbial networks. This ultimately led to an improved crop yield. At MRS, soybean as a rotational crop enriched bacterial diversity and within the AMF communities, members of the family Gigasporaceae were more dominant. We finally identified the microbial taxa highly related to crop productivity, providing cause-effect relationships for the involvement of microbes in crop productivity.

How to cite: Pellegrino, E., Piazza, G., Mhlanga, B., Arcidiacono, M., Thierfelder, C., Nuti, M., and Ercoli, L.: Effect of agricultural soil conservation practices on arbuscular mycorrhizal fungal and bacterial communities and crop productivity in two agro-ecological zones in Italy and Zambia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16863,, 2023.

On-site presentation
Marta Gil Martinez, Eve Isobel Galen, Simon Andersen, Eva Faurholdt Jørgensen, Lea Ellegaard-Jensen, Thanassis Zervas, Carsten Suhr Jacobsen, Flemming Ekelund, Kristian Holst Laursen, and Rasmus Kjøller

Soil aggregation is an important physical indicator of soil health. Aggregation result from biological and physicochemical processes in which primary soil particles and organic matter are bound. Biotic-mediated soil aggregation is mainly assisted by fungal hyphae facilitating macroaggregate formation through mechanical union and exudation of binding agents. In agricultural soils, many crops establish a symbiosis root- arbuscular mycorrhizal (AM) fungi where the extensive mycelium directly connects roots and soil aggregates. However, the relative importance and specific contributions of the belowground plant root associated microbiome to soil aggregation is still not known.

We set up a pot experiment under controlled conditions to investigate the aggregate stability of different crop species in an organic agricultural sandy soil. We manipulated the soil microbiome by planting 10 common crop species with different mycorrhizal status, 5 species with AM fungal symbiosis (barley, clover, maize, oat and wheat) and 5 non-mycorrhizal species (buckwheat, lupine, quinoa, rapeseed and spinach). We filled each pot with sandy soil sieved to 2 mm and added two sealed mesh bags, with mesh size of 40 µm to avoid roots but promoting hyphal entrance. Mesh bags were filled with the same sandy soil further sieved to 1 mm and 0.25 mm, respectively. All pots were harvested in the 10th week and biomass, roots and soil samples were processed.

Soil aggregate stability, measured by wet sieving method, showed that soils with AM fungal symbiosis became more aggregated as these soils presented a higher % in soil fractions > 500 µm and > 250 µm. Moreover, non-mycorrhizal crops soils showed a significantly higher free mineral fraction (< 63 µm), i.e. a loss of soil aggregation. Still, our results showed that no crop species, independently their mycorrhizal status, were able to form aggregates above the sieving size and not all crop species conferred the same soil aggregation. Among mycorrhizal crop species, barley and wheat showed a higher soil aggregation compared to oat and maize. Curiously, barley and wheat were the crop species with the highest AM root colonization, 74 and 69 %, respectively, as well as the soils with the highest microbial biomass C, N and their ratio. Our results showed that exists a positive correlation between microbial biomass, root colonization and soil aggregation. Further analysis will provide data on soil mycelial length as well as fungal and bacterial community profiles.

In conclusion, the mycorrhizal status of different crop species revealed the key role of AM fungi in soil aggregation and its relationship with microbial biomass; however, not surprisingly, the effects are species dependent. Our forthcoming data of the soil microbial communities and their functionality will further reveal which groups have a direct effect on soil aggregation.

How to cite: Gil Martinez, M., Galen, E. I., Andersen, S., Faurholdt Jørgensen, E., Ellegaard-Jensen, L., Zervas, T., Jacobsen, C. S., Ekelund, F., Laursen, K. H., and Kjøller, R.: Revealing the contributions of the belowground plant root associated microbiome to soil aggregation in agricultural soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11986,, 2023.

On-site presentation
Francois Rineau, Wouter Reyns, Camille Carpentier, Fons Van Der Plas, Richard Bardgett, Natalie Beenaerts, and Frederik De Laender

The impact of climate change on soil processes depends on how abiotic stressors (drought, flood, heatwave…) affect soil species physiology directly, but also indirectly through their interactions. A number of different theoretical frameworks have been designed to conceptualize the latter. The most widely used is the stress gradient hypothesis, which states that facilitation should be more common in stressful environments. However, these interactions are notoriously difficult to investigate in soils, because of the difficulty to isolate low competitor species and of the sheer number of species in soil, and therefore of interactions to test experimentally. Consequently, this topic has been traditionally approached through network analyses, that are based on frequency of co-occurrences, but has its own flaws.

In this paper, we used a combination of isolation methods to recover the widest possible range of soil fungi with randomized co-cultivation tests to cover as many interactions as possible. This way, we investigated how multiple pairwise competitive interactions were affected by abiotic stress (high temperature, low water availability).

In absence of abiotic stress, the presence of another species mostly affected growth positively, demonstrating facilitation among soil fungal species under benign conditions. In presence of temperature stress, either alone or combined with water stress, these positive effects became negative, contradicting the stress gradient hypothesis. We did not find the interaction outcomes to be predictable by some of the trait data we investigated, such as abiotic stress tolerance or intrinsic growth rate.

Overall, our results demonstrate that in a very simplified but controlled system, climate change shifts the interaction types from mostly facilitative to mostly negative. We discuss further potential implications in the presentation.

How to cite: Rineau, F., Reyns, W., Carpentier, C., Van Der Plas, F., Bardgett, R., Beenaerts, N., and De Laender, F.: Fungal pairwise interactions shift from positive to negative under warming stress, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1282,, 2023.

On-site presentation
Louis Mielke, Julien Klein, Alf Ekblad, Roger Finlay, Björn Lindahl, and Karina Clemmensen

Boreal forest soils are dominated by three fungal guilds; ectomycorrhizal fungi associated with canopy-forming trees, ericoid mycorrhizal fungi associated with understory shrubs and free-living saprotrophic fungi. We followed decomposition of pine needle litter and mor-layer humus in a factorial pine root exclusion and shrub removal experiment in a mature pine forest over three years to evaluate fungal guild effects on mass loss. Litter mass loss was 10% faster when ectomycorrhizal fungi were excluded, however this ‘Gadgil effect’ was only found in one of two litter sets, and it was independent of shrub presence. In contrast, humus mass loss was hampered by shrub presence and promoted by ectomycorrhizal fungi, although presence of both guilds resulted in the largest humus mass remaining. This suggests that saprotrophic-ectomycorrhizal interactions are of little significance for early-stage litter decomposition, while ericoid and ectomycorrhizal guilds interact to determine late-stage organic matter balance in boreal forest soils.

How to cite: Mielke, L., Klein, J., Ekblad, A., Finlay, R., Lindahl, B., and Clemmensen, K.: Mycorrhizal guild interactions, rather than the Gadgil effect, slow decomposition of mor-layer humus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8993,, 2023.

On-site presentation
Gry Lyngsie

Podsolization is influenced by soil forming factors such as precipitation, parent material, variation in e.g., snowpack melt, groundwater table, water flow velocity, and pH. However, in a thorough meta-analysis of 48 publications, containing 259 dated profiles, Zwanzig and co-authors used the formation of an E-horizon and its increase in thickness over time as an indicator of progressive podsolization1 and showed that progressive podsolization was linked to “Coniferous” and “Ericaceae-Coniferous-Mix” vegetation. Both vegetation types are affiliated with mycorrhizal fungi, which obtains energy from the host plant and in return deliver nutrients to the plant. Specifically, Coniferous and Ericaceae vegetation hosts ectomycorrhizal (ECM) and ericoid mycorrhiza (ERM) fungi, respectively. Linking ECM fungi to the podsolization process was done more than two decades ago by Van Breemen and co-authors2. They observed extensive tunnel weathering of primary minerals by ECM fungi in the top horizons which was almost absent in the underlying B-horizon, thus indicating that some ECM fungi accelerate mineral weathering in the top part of the soil and increase Al mobilization. Furthermore, within the last two decades it has been discovered that ECM fungi with diverse evolutionary origins have a large capacity to reductively dissolve iron minerals as a part of their decaying mechanism driven by Fenton chemistry3. Furthermore, genomic analyses suggest that ERM species might have the ability to initiate a Fenton reaction4 albeit this has only been experimentally verified for one species5. Here it is suggested that the ability to generate tunnel weathering and reductively dissolve iron minerals are not driven by the same mechanism, nor by the same metabolites, but can be done by (at least) two taxonomically distinct yet functionally similar groups of fungi affiliated nutrient pore soils.  Thus, it is suggested that podsolization, or at least Fe translocation in podzol, is driven by mycorrhiza fungi and is an artifact of the fungi decaying mechanism.

Zwanzig, L., Zwanzig, M. & Sauer, D. Outcomes of a quantitative analysis of 48 soil chronosequence studies in humid mid and high latitudes: Importance of vegetation in driving podzolization. CATENA 196, 104821 (2021).

van Breemen, N., Lundström, U. S. & Jongmans, A. G. Do plants drive podzolization via rock-eating mycorrhizal fungi? Geoderma 94, 163–171 (2000).

Tunlid, A., Floudas, D., Op De Beeck, M., Wang, T. & Persson, P. Decomposition of soil organic matter by ectomycorrhizal fungi: Mechanisms and consequences for organic nitrogen uptake and soil carbon stabilization. Front. For. Glob. Chang. 5, (2022).

Martino, E. et al. Comparative genomics and transcriptomics depict ericoid mycorrhizal fungi as versatile saprotrophs and plant mutualists. New Phytol. 217, 1213–1229 (2018).

Burke, R. M. & Cairney, J. W. G. Carbohydrate oxidases in ericoid and ectomycorrhizal fungi: a possible source of Fenton radicals during the degradation of lignocellulose. New Phytol. 139, 637–645 (1998).

How to cite: Lyngsie, G.: Fungal triggered iron translocation in the oxic environment - Advances in understanding podsolization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11550,, 2023.

On-site presentation
Nevo Sagi, Viraj Torsekar, J Alfred Daniel, Efrat Gavish-Regev, and Dror Hawlena

Litter decomposition in most terrestrial ecosystems is regulated by moisture-dependent biological activity, leading to a positive association between precipitation and decomposition rates. In drylands, decomposition is often higher than predicted by climate conditions and weakly associated with annual precipitation, a discrepancy known as the dryland decomposition conundrum. One possible resolution may be that low microbial decomposition is compensated by litter consuming macro-arthropods that are better adapted for activity under arid conditions. In this study we quantified the contribution of organisms of different sizes to litter decomposition across an aridity/precipitation gradient from Mediterranean (mean annual precipitation (MAP) of 526 mm) to hyper-arid climate (MAP = 22 mm). We performed a litter box experiment in seven sites along the gradient during two different seasons – a dry summer and a wetter winter. We manipulated access to litter by organism size and monitored the activity of macro-detritivorous fauna in each site during both periods. We found that microbial decomposition rate increased with MAP. However, litter mass loss induced by mesofauna and macrofauna followed a unimodal pattern, with mesofaunal and macrofaunal decomposition peaking under semi-arid (MAP = 367 mm) and arid (84-148 mm) climate conditions, respectively. This result corresponded to macro-detritivore abundance, species richness and biomass that similarly peaked in the arid sites. These patterns were consistent across seasons, but macrofaunal decomposition rates in the arid sites were 2.5- to 7-fold higher in summer than in winter. Whole-community decomposition was dictated by microbial decomposition in winter and by macrofaunal decomposition in summer. Whole community decomposition rates in arid sites during summer were as high as in the semi-arid and Mediterranean sites in winter, eliminating total differences across these climates at the annual scale. Our findings highlight the importance of macro-detritivores for litter decomposition under arid conditions, which compensates for low microbial and mesofaunal activity, advocating a possible resolution for the dryland decomposition conundrum. This is not the case under hyper-arid climate conditions, where macrofaunal activity is severely limited and cannot compensate for low microbial decomposition. We conclude that the relationship between climate conditions and decomposition is mediated by organism size. Moreover, differential adaptation of microorganisms, mesofauna and macrofauna to aridity may alleviate the dependence of decomposition on moisture availability. This new mechanistic understanding is essential for integrating faunal effects into biogeochemical models in the face of the global aridification trend.

How to cite: Sagi, N., Torsekar, V., Daniel, J. A., Gavish-Regev, E., and Hawlena, D.: Differential climate dependence of microbial, mesofaunal and macrofaunal litter decomposition across a Mediterranean to hyper-arid aridity gradient, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10025,, 2023.

On-site presentation
Thomas Z. Lerch, José H.R. Araujo, Yvan Capowiez, Anne Pando, Christian Hartmann, and Lise Dupont

Earthworms are involved in the regulation of many soil ecosystem services. Their communities are often composed of several species but the role of each species and the potential interactions among these species on soil functioning is still poorly understood. The aim of this study was to test the hypothesis that the higher the earthworm diversity, the stronger the effect on soil processes and plant growth. A second assumption relied on the fact that earthworm effects depend on soil texture. To test our hypotheses, a laboratory controlled experiment was conducted on 5L mesocosms filled with 3 grassland soils with different textures (from sandy to loamy), covered by a layer of green waste compost. In each soil, 8 combinations of 3 different species of earthworms (Lumbricus terrestris, Lumbricus castaneus, and Allolobophora chlorotica) were tested. The experiment lasted about 14 months during which the CO2 and the water holding capacity were recorded. Then, Lolium perenne were grown during 6 months. At the end of the experiment, analyses of soil porosity and aggregation were performed by X-ray-tomography followed by dry sieving. Results obtained shows that the assembly of the 3 species had the strongest effects on compost mineralization and hydric properties, depending on the soil texture. The analyses of the soil physical structure revealed that interactions between earthworm species lead to significant changes in the soil porosity and aggregation profiles. The ongoing analyses of plant biomass will determine whether the demonstrated changes in soil properties will result in changes in plant growth and physiology.

How to cite: Lerch, T. Z., Araujo, J. H. R., Capowiez, Y., Pando, A., Hartmann, C., and Dupont, L.: Interactions among earthworms species affect soil functioning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6714,, 2023.

On-site presentation
Camille D'Hervilly and Jan Frouz

Soil saprophagous fauna strongly impacts litter decomposition through its modification of microbial communities and activity. However, soil fauna is very diverse, with different feeding strategies. For example, arthropods such as woodlice and millipedes and epigeic earthworms (litter-feeders) are known to feed on the litter layer, while endogeic earthworms feed on organic particles mixed with the soil mineral layer. Distinct fauna may have a very different impact on the final forms of the soil organic matter. They could act synergistically as endogeic earthworms may require the fragmentation and incorporation of litter into the soil by litter-feeders to access their food. We performed a three-months microcosm experiment in which we tested the effect of litter fragmentation and presence of litter-feeders (isopods or epigeic earthworms of Dendrodrilus rubidus species) on the survival and change in biomass of endogeic earthworms (of Aporrectodea caliginosa species). We also tested whether different combinations of fauna and litter fragmentation affect microbial biomass and respiration, and the forms of the soil organic matter. We used a recent post mining soil, to create a stressful environment with poor food resources for the endogeic species. The hypotheses were that endogeic earthworms would be positively affected by the fragmentation and mixing of litter with the soil, whether it would be done manually or by epigeic earthworms or isopods, and that this would impact soil properties. First results showed no decrease in the biomass of A. caliginosa in any of the treatments. A. caliginosa was able to consume the alder litter added at the soil surface at a similar rate than the epigeic D. rubidus, even without previous fragmentation and in the absence of litter-feeders. A loss of carbon through respiration and an increase of dissolved organic carbon content in the soil were associated with the presence of epigeic earthworms, while an increase in soil microbial biomass carbon was induced only by endogeic earthworms when litter was added at the soil surface. Nitrates content was increased when both types of earthworms were present. Interestingly, endogeic earthworms had an opposite impact on microbial biomass and dissolved organic carbon content when litter was mixed in small pieces with the soil or added at the soil surface. First conclusions are that though the endogeic earthworm A. caliginosa do not seem to require a first fragmentation of the litter to access it, the final effect on decomposition differ according to the other fauna present and to the fragmentation of the litter. Analyses of the forms of the organic matter in the different treatments will allow to determine how this impacted the incorporation of organic matter into the soil.

How to cite: D'Hervilly, C. and Frouz, J.: Do interactions between litter-feeders and endogeic earthworms impact soil organic matter content and its forms? Results of a microcosm experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-837,, 2023.

Posters on site: Thu, 27 Apr, 10:45–12:30 | Hall X3

Chairpersons: Edith Hammer, Tullia Calogiuri, Erik Verbruggen
Jan Frouz and Saliha Irshad

Globally soil fauna can consume about half of litter fall. Important question is how this activity affect mineralization and stabilization of soil organic matter. Here we explore how much fauna effect litter decomposition and organic matter stabilization in soils of various ages supplied by litter of various quality.   Laboratory mesocosm consist from litter and mineral layer mineral soil originated either from spruce and alder stand which were growing either on post mining soils (young soil) or from soil in close vicinity of post mining sites (mature soil), mineral soils were supplied by matching litter, mesocosms were either without fauna or supplied by two individuals of earthworm Aporectodea rosea. Results show significant effect of tree, soil age and earthworm; alder respire more than spruce, young soil respire more than old soil, and mesocosms with earthworms respire more than without earthworms.  Earthworm effect show statistically significant interaction with tree and soil age, earthworms always increase respiration in alder soil, but in spruce only in mature soil while opposite was true for young soil.  In general earthworms promote removal of litter from soil surface and its accumulation in mineral soil. Earthworms promote C storage in MAOM  namely in young spruce soil. Results indicate that in young soils which are far from saturation (spruce on post mining soil) earthworm activity promote soil C storage most likely by promoting C storage in MAOM, in the contrary in mature,  C saturated soils, earthworms rather promote soil respiration.

How to cite: Frouz, J. and Irshad, S.: How the effect of earthworms on soil organic matter mineralization and stabilization is affected, by litter quality and stage of soil development., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1118,, 2023.

Maria Korneykova, Dmitriy Nikitin, Maria Vasilieva, and Viacheslav Vasenev

Among the high diversity of urban soils, of particular interest are soil constructures (Technosols) created by man to solve certain problems: landscaping and recultivation. Microorganisms quickly respond to external influences and are indicators of changes occurring in ecosystems. Microfungi determine the soil health, and the activity of saprotrophic microscopic fungi can lead to improved soil properties associated with soil fertility.

The aim of the study was to evaluate the quantitative indicators of soil fungal communities of 2-years-old Technosols, created on the basis of peat, sand and loam, in different climatic zones in comparison with background soils.

The studies were carried out in cities located in different climatic zones: subarctic (Apatity), temperate continental with a humid climate (Moscow), and temperate continental with a dry climate (Rostov-on-Don). Soil sampling was carried out at stations with soil constructures of a composition universal for all regions: peat/sand/loam in the ratio 1/1/1.

Quantitative assessment of the content of ribosomal genes of fungi was performed by real-time polymerase chain reaction (PCR). The fungal biomass was determined by luminescence microscopy method.

The predominance of fungal biomass over that of prokaryotes was revealed in all climatic zones, both in background soils and in Technosols. The fungal biomass in Technosols of different climatic zones varied from 0.073 to 0.790 mg/g of soil. In Apatity and Moscow, its values 2 years after the creation of Technosols were lower than in the background soil; in Rostov, the values were close. In the Technosols of Apatity and Moscow, microfungi were mainly in the form of mycelium, while in Rostov-on-Don, spores prevailed over mycelium. However, small spores prevailed in all zones, both in background soils and in Technosols. Over the 2-years period of Technosols development in the subarctic and the temperate zone, similar trends in the state of the fungal community were noted, while in the area with a warmer climate, other patterns were revealed.

The number of the fungal ITS rRNA ribosomal genes copies in the soils varied from 5.95×108 in the Technosols of Apatity to 3.39×109 gene copies/g soil in the background soil of the Moscow region. According to the quantitative content of fungal genes copies over a two-year period, the Technosols of Rostov-on-Don correspond to the background soils and slightly exceed the values of the latter. In the subarctic, the values of this indicator are also comparable for Technosols and background soils, while in Moscow, the number of copies of Technosols genes is 2.5 times less.

Thus, the change in the quantitative indicators of soil fungal communities over time makes it possible to judge the dynamics of the development of Technosols in different climatic zones. However, for such a short period (2 years), the state of fungal communities does not reach the state of the background ecosystems in any of the regions. We can only talk about trends in the parameters of the fungal community in the direction of background ecosystems.

How to cite: Korneykova, M., Nikitin, D., Vasilieva, M., and Vasenev, V.: Microscopis fungi of Technosols in cities of different climatic zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2092,, 2023.

Tullia Calogiuri, Mathilde Hagens, Jan Willem van Groenigen, and Alix Vidal

Enhanced Silicate Weathering (ESW) has emerged as a promising Carbon Dioxide Removal (CDR) technology. However, it is still not clear which factors could maximize ESW rates. Previous studies have shown the potential of soil biota to amplify mineral weathering rates. Among the relevant soil biota are earthworms, which have been found to enhance nutrient release from soil minerals. This is indicative of their ability to increase weathering rates and further inorganic carbon (C) sequestration. Here we aim to accelerate ESW rates in a bio-reactor through earthworm activity. First, we identified the optimal conditions for earthworm survival and activity in an environment exclusively composed of ground silicate rocks and organic substrate. Second, we determined to what extent earthworms can enhance inorganic C sequestration in such a system. We carried out 5 rounds of 2-month experiments in a climate chamber at 25°C. The set-up of the experiments consisted of 200 columns, each topped by a sprinkler connected to an irrigation system, which allowed for different water irrigation rates and watering frequencies. The leachate of each column was collected in a jerrycan kept at 4˚C. Within this set-up, we used two endogeic earthworm species (Aporrectodea Caliginosa and Allobophora Chlorotica) at different densities (10, 20, and 30 earthworms kg-1 soil), three types of rock flours (Basalt, Lava and Dunite) of two grain sizes (0.063 and 1.5 mm), one organic source (straw) and two water irrigation rates (125 and 250 ml day-1 kg-1 soil) at three watering frequencies (1, 2 and 5 times/day). Rock flours were used not only as single type or single size, but also as mixtures of types and/or sizes. At the end of each experiment, we measured earthworm survival and activity, and inorganic C sequestration rates by summing cumulative dissolved inorganic C in the leachate and the newly formed solid inorganic C content. We found no differences in survival and activity between the two earthworm species, but we did find an optimum for both parameters at a density of 10 earthworms kg-1 soil. Earthworms showed a clear preference for a mixture of grain sizes compared to single size, and for single mineral type compared to a mixture of mineral types. The response of earthworm survival and activity to the two water irrigation rates was similar, but at a water irrigation rate of 250 ml day-1 kg-1 soil a frequency of 5 times/day resulted in higher activity. Preliminary results indicate that earthworms increase mineral weathering rates and thereby sequester inorganic C. We demonstrate that earthworms can thrive in a fully artificial environment designed to ESW rates, removing one hurdle for designing a bio-reactor aimed at optimizing carbon sequestration.

How to cite: Calogiuri, T., Hagens, M., van Groenigen, J. W., and Vidal, A.: Can earthworms increase inorganic carbon sequestration in an artificial environment?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3352,, 2023.

Anna Sophia Holmer, Kaiyu Lei, Sigrid van Grinsven, and Jörg Völkel

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.

How to cite: Holmer, A. S., Lei, K., van Grinsven, S., and Völkel, J.: Nutrient Dynamics in Soil and Soil Water impact Arbuscular Mycorrhizal Fungi (AMF) Colonization and Abundance on Grassland Slopes in Eastern Bavaria, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6338,, 2023.

What do millipedes actually eat, and how is their microbiome involved?
Roey Angel, Julius Eyiuche Nweze, Shruti Gupta, and Vladimír Šustr
Monika Schmoll, Miriam Schalamun, Sabrina Beier, Ida Scalmani, Stephane Compant, and Wolfgang Hinterdobler

In nature, complex organismic communities have evolved for optimal colonization of habitats. Interkingdom interactions between fungi and bacteria can be mutualistic, but also parasitic. Ongoing research reveals an increasing number of fungi inhabited by bacteria, which results in diverse phenotypic alterations in fungi. Therefore, we were interested, how widespread the presence of endofungal bacteria is in strains of the genus Trichoderma, which fulfil a variety of ecological functions – from beneficial plant interaction and mycoparasitism on pathogenic fungi to degradation of cellulosic litter.

We found evidence for the presence of endohyphal bacteria of different species in the majority of Trichoderma strains tested. Interestingly, we did not detect a preference of specific bacterial species for a fungal species or vice versa. In the saprophyte Trichoderma reesei, we detected endohyphal bacteria by confocal microscopy and specific staining. We could confirm the presence of a Methylobacterium species in the hyphae by sequencing of 16S rRNA. After curing T. reesei QM6a from the bacteria using antibiotics, re-sequencing of the 16S rRNA and whole genome sequencing of the isolated bacterium confirmed its identity. Again, the association with Methylobacterium turned out to be strain specific with strains from different tropic habitats than species specific. Isolation of the bacterium from T. reesei QM6a showed that it is not obligate biotroph and both the bacterium and the fungus are viable individually.

In order to evaluate the interrelationship of Methylobacterium and T. reesei, we applied phenotype microarrays to assess metabolic contributions of the bacterium and performed functional assays. Antagonism against pathogenic fungi on plates was not perturbed in the absence of Methylobacterium from T. reesei on no general growth defect was obvious. However, BIOLOG analysis clearly showed a light dependent alteration of growth in the cured strain especially on xylitol, an intermediate of hemicellulose degradation and D-mannitol, a carbohydrate with important roles in stress response and carbon storage.

Accordingly, comparative transcriptome analysis between wild-type and cured fungal strains indicates an influence of the endohyphal Methylobacterium of T. reesei QM6a on diverse metabolic pathways, with different patterns upon growth in light or in darkness. The hypothesis, that the endohyphal bacterium of T. reesei QM6a supports the metabolic adaptation of the fungus to growth in light is corroborated by sequencing the genome of Methylobacterium, which comprises multiple genes with light-response associated protein domains.

In summary, we discovered an intriguing new physiological aspect of T. reesei, which opens up a new field of research with high potential for gaining an in depth understanding of interkingdom interaction of fungi with their prokaryotic inhabitants. On a broader scale, our findings highlight the abundance and important interaction of soil fungi with their endohyphal bacteria for ecosystem functions like carbon degradation, which is currently hardly considered in microbiome research and warrants further studies into the role of such interkingdom interactions in microbial communities.

How to cite: Schmoll, M., Schalamun, M., Beier, S., Scalmani, I., Compant, S., and Hinterdobler, W.: An endohyphal bacterium impacts growth and metabolism of carbohydrates associated with storage and hemicellulose degradation of its fungal host, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8071,, 2023.

Kian Jenab, Lauren Alteio, Stefan Gorka, Ksenia Guseva, Sean Darcy, Lucia Fuchslueger, Alberto Canarini, Victoria Martin, Julia Wiesenbauer, Felix Spiegel, Bruna Imai, Hannes Schmidt, Karin Hage-Ahmed, Erich M. Pötsch, Andreas Richter, Jan Jansa, and Christina Kaiser

Arbuscular mycorrhizal fungi (AMF) form mutualistic associations with roughly 70% of vascular plant species, supporting the nutrient acquisition of their host plants and deriving carbon in return. AMF and plant communities are linked to each other by host-specificity and the ecological selection of favorable nutrient and carbon trading strategies. Changing soil nutrient availabilities can affect both plant and AMF communities directly and also indirectly via the response of their partners.  We aimed to elucidate the combined response of AMF (belowground) and plant (aboveground) community compositions to changing soil nutrient availabilities.

We sampled soil and roots from a long-term nutrient deficiency experimental grassland in Admont (Styria, Austria). The grassland plots have been fertilized with different combinations of nitrogen (N), phosphorus (P), and potassium (K) over 70 years. Aboveground biomass cuts were removed three times each year, leading to long-term deficiencies of nutrients not replaced by fertilizers. Soil and root AMF community compositions were measured by DNA and RNA amplicon sequencing of the 18S rRNA gene. In addition, we assessed the plant community composition of the sampled roots by amplicon sequencing of the chloroplast rbcL (RuBisCo large subunit) gene region, and visually recorded the plant community composition on each investigated plot.

Our results demonstrate that N and P deficiencies influenced soil AMF community composition, whereas K deficiency had a major impact on root AMF community composition. Interestingly, the plant community composition was affected by N and P, similar to the soil AMF community composition. Both, soil and root AMF community compositions were significantly correlated to plant community composition across all treatments, the correlation was however stronger for soil AMF communities (R2 = 0.55, p< 0.001). By using bipartite network analysis, we identified several fungus-plant pairs that responded consistently to treatments.

Our results indicate that the response of grasslands to nutrient deficiencies is potentially driven by strong feedbacks between plant and belowground AMF community compositions. We here demonstrate that the known interactions between grassland plants and AMF - which are often investigated from a single plant or monoculture perspective - are major drivers of how diverse plant community compositions will respond to environmental change, such as fertilization. In conclusion, considering the ecology of the subsurface AMF communities may strongly benefit our understanding of plant communities in a future environment.

How to cite: Jenab, K., Alteio, L., Gorka, S., Guseva, K., Darcy, S., Fuchslueger, L., Canarini, A., Martin, V., Wiesenbauer, J., Spiegel, F., Imai, B., Schmidt, H., Hage-Ahmed, K., Pötsch, E. M., Richter, A., Jansa, J., and Kaiser, C.: Arbuscular mycorrhizal fungi and their associated plant communities jointly respond to long-term nutrient deficiencies in a managed grassland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9220,, 2023.

Kyle Mason-Jones, Cassidy Dietz, Mark Zwart, Johannes Helder, and Lisa van Sluijs

Lytic bacteriophages are major drivers of bacterial mortality and biogeochemical cycles in several ecosystems, roles that have also been hypothesized in soil. Phage particles have no metabolism of their own, yet to achieve sustainable replication they must travel from one host to the next through the surrounding environment. Evidence from soil physics and phage biology suggests that this is a hazardous journey for unprotected phages, especially under the prevailing assumption that dispersal occurs by diffusion. However, many other viruses overcome dispersal challenges by taking advantage of vectors – third-party organisms that carry the virus from one host to the next. We hypothesized that bacterivorous nematodes play this role in soil, picking up phages while feeding on bacteria and transferring them to uninfected bacteria while foraging. We postulated that nematodes would provide active and directed transport of phages between bacterial patches via two possible mechanisms. First, nematode intestines could temporarily harbour infected bacteria during nematode movement. Second, nematodes could carry phages through external attachment to the nematode cuticle. Using experiments with model nematodes (C. elegans) and bacteria (E. coli, P. putida) along with phages (T7, Phi Ppu-W11) we confirmed that transfer occurs at high frequency when facilitated by nematodes, and does not occur without nematodes. Resource availability was found to influence the transfer by modulating nematode behaviour in agar, but this effect was not found in structured compost habitats. Based on these results we propose that vectors are crucial for soil phage dispersal, suggesting that phage roles in soil function are mediated by interactions with local fauna.

How to cite: Mason-Jones, K., Dietz, C., Zwart, M., Helder, J., and van Sluijs, L.: Nematode hitchhiking in soil bacteriophage dispersal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10742,, 2023.

Joanne O'Keeffe, Jeppe Aagaard Kristensen, Camilla Fløjgaard, and Carsten W. Müller

Animal grazing is known to affect both, soil carbon storage and above and belowground biodiversity. However, we lack a more detailed understanding how specific soil properties might determine biodiversity and soil carbon storage as affected by grazing. Thus, in the present work we aim to connect the geo- and biodiversity with organic matter decomposition functionalities of the soil community, and thus identify how this regulates soil carbon and nitrogen storage. Therefore, we analysed aboveground plant biodiversity, soil microbial functional diversity, and soil organic matter (SOM) characteristics on a summer grazed island (Eskilsø) in a Danish fjord. Specifically, plant biodiversity analyses were conducted and topsoils sampled at thirty plots (4 replicated soil samples per plot) on the ca. 140 ha island. The plots cover the island’s main habitats: salt meadows, meadows, and developing dry grasslands. Soils were analysed for organic carbon (OC), total nitrogen (TN), organic phosphorus (OP), inorganic phosphorus (IP), and pH. Additionally, community level physiological profiles (CLPP) were analysed using the Microresp technique to make inferences about soil microbial functional diversity and activities. 
We are able to demonstrate that plant biodiverse plots contained greater contents and stocks of SOM. This also correlates with an increased soil microbial functional diversity. The findings are in line with the often observed positive interaction between aboveground diversity and belowground functionality of the soil biome in grassland ecosystems, partly due to increased amounts and diversity of rhizodeposits. As microbial activity is important for mediating the turnover of plant derived organic matter into more stable soil OM pools, this reflects the correlation with higher soil OC stocks and thus links to soil carbon persistence. For the studied island ecosystem we are able to demonstrate how the fate of soil organic matter is functionally linked to the interactions between above- and below-ground components of the ecosystem. 

How to cite: O'Keeffe, J., Aagaard Kristensen, J., Fløjgaard, C., and Müller, C. W.: Interplay between aboveground plant biodiversity, soil organic matter, and soil microbial functional diversity in a grazed Danish island ecosystem, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11680,, 2023.

Alberto Canarini, Jinsen Zheng, Keisuke Koba, Joana Séneca, Kazumichi Fujii, Saori Furukawa, Mie Honjo, Hiroshi Kudoh, Takanori Nishino, Yoshihiro Kobae, Kei Hiruma, Kazuhiko Narisawa, Katie Field, Yin-Tse Huang, Toby Kiers, and Hirokazu Toju

Root fungal endophytes are present in most plants and co-occur with other mycorrhizal fungi. Their intraradical colonization suggests a special, differentiated relationship with host plants and increases opportunities for close interactions between hosts and fungal symbionts (e.g., carbon to nutrient exchange or hormone signalling). During the symbiosis between plant and arbuscular mycorrhizal fungi (AMF), specific trading features are established. These features have been incorporated into the biological market hypothesis, where dynamics of carbon to nutrient trading in the plant‐mycorrhizal fungal mutualism are compared to trades in a market economy. Multiple examples of similar dynamics have been shown for root endophytic fungi: soil nutrients are transported to the plant in exchange for carbon. However, plants have been shown to be able to reward AMF that exchange larger amount of nutrients (and vice versa), while at least some root fungal endophytes have been described as “by-product mutualists”, where the fungal symbiont enhances the performance and fitness of their host plant by providing benefits, but not requiring major investments from the host. Whereas AMF have received large attention, the role of fungal endophytes in carbon to nutrient exchange with plants remains largely uninvestigated.

In this study we aimed at developing a controlled system to evaluate effects of multiple fungal endophytes (Colletotrichum tofieldiae and Cladophialophora chaetospira) on a model plant species (Lotus japonicus) and their role in the carbon to nitrogen exchange in the presence of different nitrogen sources (organic and inorganic). We further developed this controlled system to include plants colonized by AMF. Two-compartment petri dishes were used to achieve plant root colonization in a nutrient limited compartment and allow separation of nutrient sources only accessible by the fungal endophytes. We performed dual 15N and 13CO2 pulse-labelling experiments to trace the fate of plant carbon into fungal biomass and of different nitrogen sources into plant aboveground tissues. We analysed root for RNA sequencing to gain insights into the genetic controls over the observed dynamics.

We successfully established a controlled system and found that C. tofieldiae can elicit positive effects on plant growth and nitrogen acquisition. These effects are dependent on the nutrient source to which the fungus has access to, with positive effects displayed in the presence of organic nitrogen. Plants exchange relatively less carbon to C. tofieldiae accessing organic nitrogen. Root transcriptome shows specific changes in response to root fungal colonization which are dependent on the nitrogen source available to the fungal endophyte. Furthermore, the presence of AMF did not modify the observed carbon to nitrogen exchange dynamics.

In conclusion we show that the root fungal endophyte C. tofieldiae can play an important role for plant nutrient acquisition in the presence of organic nitrogen. The trade of nitrogen for plant carbon displays different features from the AMF symbiosis (i.e., higher amount of nitrogen is not rewarded with plant carbon investment) and different gene regulations are involved. Our results indicate complementarity between C. tofieldiae and AMF during root colonization, offering mechanistic explanations for the concomitant presence of AMF and fungal endophytes in terrestrial ecosystems.

How to cite: Canarini, A., Zheng, J., Koba, K., Séneca, J., Fujii, K., Furukawa, S., Honjo, M., Kudoh, H., Nishino, T., Kobae, Y., Hiruma, K., Narisawa, K., Field, K., Huang, Y.-T., Kiers, T., and Toju, H.: Fungal root endophytes and their role in carbon to nitrogen exchange with plants, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12246,, 2023.

Philipp de Jong, Patrick Schleppi, and Frank Hagedorn

Earthworms may act as double-edged swords for soil organic matter (SOM). While they can enhance organic matter (OM) mineralization via increased microbial activity they can also elevate OM stabilization in aggregates as particulate or mineral-associated OM. In this study, we will test this potentially opposing impact in beech (Fagus sylvatica L.) forests on limestone, a forest ecosystem with particularly high earthworm activity. A specific focus will be on OM transformation along the continuum from the forest floor (O horizons) to mineral soil (A horizons). The forest floor can represent a substantial OM-pool which is an important source for SOM formation via bioturbation or leaching but can be vulnerable to alterations due to climate change. In an extended lab mesocosm experiment, we will incubate local earthworm species in soil columns consisting of O and A horizons from four beech forest sites along an elevation gradient from 550 to 1250 m in the Swiss Jura Mountain range. Along this gradient, the dominating forest floor type is mull with its thickness increasing with altitude. We will establish the following three treatments (1) control with soil and unlabeled litter, (2) with soil and labeled litter and (3) with soil, labeled litter, and earthworms. For this setup, the Ol horizon will be replaced with beech litter highly enriched with 13C, 15N, and 2H. Soil respiration (CO2) and leaching (C, N, and H in dissolved OM) will be repeatedly measured. Our setup will allow for a separation of fluxes from the O horizons and the A Horizon. After approximately 4, 7, and 10 months each, a subset of mesocosms will be harvested to investigate isotope enrichment in earthworm biomass, earthworm casts, physical soil fractions, PLFAs, and microbial necromass. This will allow us to establish a mass balance of beech litter turnover as affected by earthworms for a time scale representative of one vegetation period. Fluxes of unlabeled OM will inform on the fate of inherent SOM. We expect that (1) following an initial colonization phase, earthworms will stimulate labeled litter mineralization and enhance litter transfer to aggregate fractions while not affecting the total SOM stock. (2) In the long term, less of the labeled material will be mineralized and more SOM stabilized in aggregate fractions will be recycled.

How to cite: de Jong, P., Schleppi, P., and Hagedorn, F.: Earthworms as double-edged swords for organic matter turnover from forest floor to mineral soil – a mesocosm experiment with labeled beech litter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12586,, 2023.

Hongbo Yang, Jeroen Meersmans, Gilles Colinet, Wenju Zhang, and Qiong Xiao

It’s well known that agroecosystems have a great carbon sequestration potential. Within this process plays Arbuscular mycorrhizal fungi (AMF) an important role. Glomalin is a recalcitrant carbon fraction processed from AMF, its accumulation in response to fertilization is unclear. Here, we used a 30-year various fertilization experiment, including CK, NPK, NPKM, NPKS, M, NPKMR, and Fallow treatments, to observe the temporal trend of GRSP in bulk soil as well as across different aggregates. Meanwhile, we combined soil abiotic (pH, nutrients, MWD, GRSP chemical composition) and biotic (AMF biomass and diversity) properties to distinguish the mechanisms of long-term different fertilization on GRSP accumulation. Our results showed that GRSP content increased with time under both the fertilization and fallow treatment, but remained unchanged under the CK treatment. Manuring (M, NPKM, NPKMR) significantly increased GRSP content by increasing recalcitrance (aromatic) C in GRSP and mass percentage of macroaggregates (>0.25mm) compared with no (CK) and mineral fertilization (NPK) treatments. Manuring increased mean weight diameter (MWD) and GRSP content in macroaggregates (>0.25mm), relative to CK and NPK. There was a significant positive correlation between MWD and GRSP content in macroaggregates (>0.25 mm). Organic fertilizer also increased the proportion of aromatic C in GRSP, AMF biomass and diversity in cropland. Random forest and variance partitioning analysis showed that chemical composition of GRSP and aggregate stability together controlled the accumulation of GRSP. The structural equation model indicated that AMF properties regulate soil aggregate stability and composition of GRSP, which mediates the effects of fertilization on GRSP accumulation. In summary, long-term manuring promotes the GRSP accumulation, mainly be ascribed to the increased of AMF biomass, diversity, corresponding GRSP recalcitrance and aggregate stability. This study contributes to the understanding of the fertilization impacts on GRSP accumulation, and provides a feasible way forward for long-term soil carbon sequestration in sustainable agriculture.


How to cite: Yang, H., Meersmans, J., Colinet, G., Zhang, W., and Xiao, Q.: Long-term manuring enhances glomalin-soil-carbon sequestration by increasing its recalcitrance and macro-aggregation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13605,, 2023.

Hanna Jonsson, Gesche Blume-Werry, Adrian Wackett, Emeli Arvidsson, Oscar Lundgren, and Jonatan Klaminder

Arctic soils store nearly half of the global soil organic carbon, but what will happen with this large carbon pool if soil macrofauna, able to ingest organic matter accumulated at depths in the soil, establish in the Arctic? The question is justified as emerging evidence suggests that low soil organic carbon (SOC) turnover rates in high latitude ecosystems could, in addition to abiotic factors, partly be due to the current lack of larger detritivores that can stimulate the breakdown of organic matter. Earthworms are large detritivores increasing their distribution into arctic ecosystems. With potential to both increase stabilisation and decomposition of SOC, but also enhance plant productivity, it has been difficult to determine what net effect earthworms have on ecosystem C storage. The scientific debate around this ‘earthworm dilemma’ has however primarily focused on the fate of SOC in response to earthworms, leaving cascading effects on plant productivity largely undiscussed.

Here, we use a four-year outdoor experiment to study the effects of introducing earthworms to tundra vegetation types on both plant biomass (above and belowground) and SOC. We found that earthworms invasive to the Arctic: i) reduced the SOC pool beneath herb dominated tundra while they increased the SOC pool under dwarf-shrub dominated tundra; ii) increased the below ground biomass in both vegetation types; and iii) increased the total plant biomass C to the degree that it offset the SOC losses from the herb dominated soil. In the dwarf-shrub vegetation, earthworms increased both the plant C pool and the SOC pool resulting in a net increase of the ecosystem C stock. We highlight that the effect on root growth seems of great importance when predicting how ecosystem C sequestering responds to invasive earthworms. Both through increased plant biomass C but also through increased deposition of persistent root-derived organic matter.

How to cite: Jonsson, H., Blume-Werry, G., Wackett, A., Arvidsson, E., Lundgren, O., and Klaminder, J.: Increased tundra root biomass offset invasive earthworm effects on SOC decomposition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14905,, 2023.

Ashish Ahlawat and Dimitrios Floudas

Wood decomposition has been studied extensively due to its importance in wood deterioration and carbon cycling processes. Wood decaying fungi are categorised into white rot, soft rot and brown rot. White rot fungi have an enzymatic mechanism by which they can digest lignin and crystalline cellulose. Instead, brown rot fungi lack the enzymes to digest lignin and crystalline cellulose. Several hypotheses have been made on the mechanism by which brown rot fungi mine carbon out without the required enzymes mainly focussing on extracellular metabolites and metal ions. Here, we investigate chemical and structural modifications on cellulose produced by saprotrophic fungi using Raman specrtroscopy under different conditions. In additions, known modifications introduced by chemicals on cellulose will also be compared to fungal changes on cellulose.

How to cite: Ahlawat, A. and Floudas, D.: Characterization of cellulose decomposed by saprotrophic fungi using Raman spectroscopy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16494,, 2023.

Andrey Zuev, Ina Schaefer, Nguyen Van Thinh, and Anna Zueva

Mycorrhizal fungi play a vital role in soil processes and form a large part of belowground biodiversity in tropic ecosystems. Unlike temperate forests, many tree species in tropical stands are dominated by arbuscular mycorrhizal fungi (AMF), which form high amount of extraradical mycelium and even rhizomorphs, penetrating both soil and leaf litter. The quantification of mycelium biomass in natural systems often being conducted with the use of sand filled in-growth mesh bags made of nylon mesh [1]. The use of plastic polymer for mesh bags in temperate systems is justified by low bioavailability of the material that can be hardly decomposed by soil bacteria and fungi or penetrated by roots or soil invertebrates. In a number of tropical forests, the activity of invertebrates is more aggressive, mostly due to the termites foraging, resulting in the disruption of the integrity of the mesh bags and consequent samples loss.

Here we introduce the use of dual-walled in-growth mesh bags made of nylon and stainless steel. Its relevance was attested in Dong Nai (Cat Tien) National Park in Southern Vietnam. The harvested biomass of extraradical EMF mycelium and taxonomic composition of EMF and AMF fungi was compared in regular and dual-walled in-growth mesh bags across two tropical rainforests, dominated by both EMF and AMF associated tree species. The biomass was accessed with PLFA analysis for fungal biomarkers 18:2ω6,9, 18:1ω9 [2] and 18:0 [3]. The taxonomic composition of extraradical mycelium from harvested in-growth mesh bags was studied with new-generation sequencing, including specific primer pair WANDA/AML2 for the SSU ribosomal RNA gene of AMF fungi and ITS fragment (primer pair ITS3/ITS4) for ectomycorrhizal fungi.

Double-walled mesh bags remained completely intact, while about 40% of regular mesh bags were damaged by termite activity after 180 days of exposure. The biomass of extraradical mycelium of ectomycorrhizal fungi was comparable between forests dominated by EMF and AMF associated trees and reached 114.5 and 122.1 µg of «fungal» carbon g-1 of substrate respectively. The total amount of the three measured PLFA biomarkers did not differ between both variants of in-growth mesh bags and surrounding soil, while the median values were slightly higher for mesh bags compared to soil (1.9 and 1.6 µg g-1 of substrate respectively). Application of ITS fragment was 100% positive among harvested mycelium samples from both forests, while AMF fungi were detected in 62% of samples from the forest dominated by AMF-associated trees and 70% samples from the forest dominated by EMF-associated trees.

This study was supported by Alexander von Humboldt Foundation (project 3.4-1071297-RUS-IP).


[1] Wallander H, Nilsson LO, Hagerberg D, Bååth E (2001) Estimation of the biomass and seasonal growth of external mycelium of ectomycorrhizal fungi in the field. New Phytol 151:753–760.

[2] Ruess L, Chamberlain PM (2010) The fat that matters: Soil food web analysis using fatty acids and their carbon stable isotope signature. Soil Biol Biochem 42:1898–1910.

[3] Chen J, Ferris H, Scow KM, Graham KJ (2001) Fatty acid composition and dynamics of selected fungal-feeding nematodes and fungi. Comp Biochem Physiol B Biochem Mol Biol 130:135–144.

How to cite: Zuev, A., Schaefer, I., Van Thinh, N., and Zueva, A.: Armored mesh bags: collecting mycelium of mycorrhizal fungi in a tropical rainforest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16888,, 2023.