Mycorrhizal fungi connect with plant roots and facilitate exchange of nutrients (N) and carbon (C) in a symbiotic relationship between fungi and plants, sometimes linking multiple plants in a mycorrhizal network. The question is, do such networks support resource sharing among plants? In this talk I will discuss potential mechanisms of resource transfer among plants and their plausibility based on current theory and empirical knowledge. Mycorrhizal networks have sparked a huge interest not only among ecologists but also in popular media, where it has become a “wood wide web” claimed to serve as the trees’ internet for communication and as a social support system for sharing resources. As the stories have moved far beyond the scientific evidence, a debate has started among scientists about the true nature of the network and its ecological role. Because of the dynamic and cryptic existence of fungal hyphae underground, and the many other potential ways resources can move in the soil, it has been difficult to obtain reliable quantifications of C and N transport between plants through the network. In absence of empirical facts, theoretical models may guide us in terms of what is possible or likely, based on the principles of nature and our current state of knowledge. The classic C-N trading relationship between single plants and fungi is well established and more recent market models can also explain differentiation among multiple trading partners, as well as stabilizing ecosystem level feedbacks. It is more challenging to explain resource transfers in the opposite direction, such as a C transport from fungi to plants, which is necessary for trees to supply carbon to other trees via the mycorrhizal network as implied by the mother-tree hypothesis. Do we need more complex market models, or are there completely different mechanisms at work?
How to cite: Franklin, O., Henriksson, N., N. Högberg, M., Marshall, J., and Näsholm, T.: Mycorrhizal networks and mother trees – what is theoretically possible?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6330, https://doi.org/10.5194/egusphere-egu25-6330, 2025.
Mycorrhizal fungi and plants form symbiotic relationships that are essential for plant nutrition and carbon (C) storage in soil. Plants invest photosynthetically fixed C in their fungal partners in exchange for nutrients, especially nitrogen (N), which the fungi obtain from inorganic sources or by breaking down organic matter. This exchange also helps to stabilize root-derived C, as mycorrhizal necromass can persist in the soil, but it can also promote C loss when mycorrhizal fungi act as decomposers. Capturing these relationships in process-based models is crucial for quantifying C and N cycles and understanding how mycorrhizae influence ecosystem processes.
In this study, we utilized an ecosystem model calibrated with field data from a boreal forest in northern Sweden to compare ecosystem functions with and without ectomycorrhizal fungi (EMF) and to investigate how variations in parameters encoding microbial traits affect model outcomes. Through simulations involving different scenarios of elevated CO₂ and N deposition, both individually and in combination, we assessed how the presence or absence of EMF influences ecosystem responses.
We found clear differences between ecosystems with and without ectomycorrhizal fungi. Plant productivity and saprotrophic biomass were generally higher and soil C more stabile when EMF were present in the ecosystem model. But, EMF also increased decomposition resulting in higher plant growth at the cost of reduced soil C storage. Increasing CO2 and N deposition had similar effects in most of the cases. However, N addition had little effect on soil organic N suggesting that plants and microbes together control the soil organic N pool.
These findings demonstrate the significance of ectomycorrhizal fungi in influencing ecosystem responses to changing environmental conditions and highlight the benefit of including microbial interactions in ecosystem models to improve predictions of C and N dynamics.
How to cite: Forsberg, M., Lindahl, B., Spohn, M., Wild, B., and Manzoni, S.: Mycorrhizal fungi enhance plant productivity but reduce soil organic matter stocks, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18224, https://doi.org/10.5194/egusphere-egu25-18224, 2025.
Nitrogen availability often limits photosynthesis and growth in boreal forests, where nitrogen is a key constraint for plant productivity. Trees and other plants acquire nitrogen through a complex belowground interface comprising fine roots, symbiotic, and non-symbiotic microorganisms. To sustain this interface, photosynthetically derived carbon is allocated to fine root growth, mycorrhizal symbiosis, and exudation—either into the surrounding soil or directly to associated microbial communities. These exudates serve as critical energy sources for both symbiotic and non-symbiotic microbes, which, in turn, provide nitrogen to the tree through direct transfer or organic matter decomposition. This highlights the importance of the entire belowground infrastructure in the nitrogen acquisition of trees.
This study investigates carbon-nitrogen dynamics in boreal forest ecosystems with an emphasis on eco-evolutionary processes and ecosystem function. Specifically, three nitrogen transfer strategies—game theory, optimization, and fixed ratios—are analysed from the perspectives of Scots pine roots and their ectomycorrhizal partners. This framework aims to illuminate the underlying relationships governing carbon exchange and nitrogen acquisition, contributing to ongoing debates on carbon source-sink dynamics and contrasting models of carbon allocation, including the "Surplus Carbon Hypothesis" and "Biological Market Models".
The approach integrates a custom soil model, an adapted ectomycorrhizal model based on, a tree growth model (CASSIA), and a modified photosynthetic assimilation model (p-hydro) that incorporates nitrogen limitations. By including both symbiotic and non-symbiotic microbes, the study aims to capture nutrient cycling feedbacks, such as the priming effect, and explore microbial community shifts driven by functional dynamics.
Incorporating seasonal variability and rigorous modelling of tree carbon storage, allocation, and exudation provides insights into how these patterns influence next year's growth and soil ecosystem functioning. Additionally, accounting for temperature and soil moisture effects enables the disentanglement of environmental influences from sugar inputs in driving belowground processes. This comprehensive framework offers a robust tool for understanding nutrient dynamics and tree-microbe interactions in boreal forests under changing environmental conditions.
This work is in the calibration stage so preliminary results will be presented. These include soil-side results, such as trenching simulations to capture the change in microbial composition and their contribution to the priming effect. On the tree side; simulations including determination of differing root growth by the value of nitrogen in the optimisation of photosynthesis will be presented. Additionally, a comparison of three photosynthesis input models and two sugar allocation models within the CASSIA framework is conducted to evaluate the effects of differing modelling approaches.
How to cite: Simms, J., Stefaniak, E., joshi, J., Schiestl-Aalto, P., Franklin, O., Heinonsalo, J., and Mäkelä, A.: Mid-Project Analysis of Carbon and Nitrogen Transfer in Boreal Forests Using Game Theory, Optimization and Fixed Ratios , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17131, https://doi.org/10.5194/egusphere-egu25-17131, 2025.
Rotation forestry based on clear-cutting is a common practice in boreal forests. Clear-cutting has detrimental short-term effects on ectomycorrhizal fungal communities, and the communities that re-establish after clear-cutting differ in species composition from old forests, but the long-term time trajectories of ectomycorrhizal fungal biomass, species richness and community composition in secondary forest remains uncertain. We collected soil samples from almost 1600 locations distributed systematically across Swedish coniferous forests, in conjunction with the Swedish National Forest and Forest Soil Inventories, and analysed ectomycorrhizal fungal communities by sequencing of amplified ITS2 markers.
We found that the relative abundance of ectomycorrhizal species in the fungal community increases to similar levels as before clear-cutting within two decades. In the following decades, species richness increases to a somewhat higher level than in old stands, peaking about 40 years after harvesting. Clear-cutting has strong and long-lasting effects on the composition of ectomycorrhizal fungal communities, with harvesting effects remaining for up to 100 years. Many species that attain high abundance in old forests (mainly certain Cortinarius and Russula species) are adapted to the acidic, unfertile soil conditions and have a well-developed capacity to mobilise nutrients from recalcitrant organic matter. These species are negatively affected by rotation forestry, which raises pH and increases nutrient availability.
This means that rotation forestry based on clear-cutting seems to be sustainable with regards to the abundance and species richness of ectomycorrhizal fungi, which return to pre-harvest levels well within the time limits of a rotation period and even reach somewhat higher levels than in old forests. However, rotation forestry progressively changes the ectomycorrhizal community at the landscape level. Many of the species that are characteristic of the predominantly nutrient poor and acidic boreal forests decrease in abundance. This declining community is also likely to contain many rare species, which risk extinction in large areas if transformation of the forest landscape proceeds.
How to cite: Lindahl, B., Clemmensen, K., Stendahl, J., and Dahlberg, A.: Clear-cut forestry has long-term effects on the community composition of ectomycorrhizal fungi in boreal forest, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17953, https://doi.org/10.5194/egusphere-egu25-17953, 2025.
The Kranzberg Roof Experiment investigates the impact of five years of recurrent drought and subsequent recovery in a mature forest of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies [L.] KARST).
Within this framework, we studied fine-root-associated fungal communities, fine-root vitality, and ectomycorrhizal functionality in relation to mixed and monospecific tree root zones.
Changes in the fungal community peaked in the third year of drought but later stabilised, indicating a gradual acclimatisation to drought over time that was maintained during early recovery. Thereby, tree species was the dominant factor in structuring root-associated fungal functional groups, suggesting a strong relationship with tree-species-specific fine-root reactions to drought.
However, the trees’ root-fungal systems were functionally resilient, and the system's capabilities were mainly quantitatively affected due to the loss of surviving fine roots.
This fits well with results that quantitative effects (e.g., fewer leaves – fewer fine roots) may have driven tree acclimation. Beyond that, it suggests that the surviving root-fungal systems (i.e., ectomycorrhizal root tips) functioned as moist islands within dried-out soil, kept alive by an interplay between tree-redistributed water and fungal symbionts. Elucidating this is one of the challenging topics for the final phase of the Kranzberg Roof Experiment, a terminal drought now beginning.
How to cite: Weikl, F., Danzberger, J., Hikino, K., Grams, T., and Pritsch, K.: Biotrophic root-fungal systems of beech and spruce acclimatised to five years of repeated experimental drought., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6851, https://doi.org/10.5194/egusphere-egu25-6851, 2025.
How to cite: Godbold, D., Lan, H., Markus, G., and Otgonsuren, B.: Freezing Tolerance of Ectomycorrhizal and Saprotrophic Fungi, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21819, https://doi.org/10.5194/egusphere-egu25-21819, 2025.
Light reflectance by foliage across visible and infrared wavebands is determined by chemical and structural traits that reveal how plants evolved to support growth and defense in different climate and environments. These spectral fingerprints have emerged as powerful tools to estimate plant functional and taxonomic diversity across scales, giving rise to a new approach in ecology called spectranomics. In this context, the widespread co-evolution of plants with different mycorrhizal fungi has likely led to chemical, structural and thus spectral dissimilarities that are strong enough to be intrinsic features of each mycorrhizal association. Such spectral dissimilarities may therefore help to better estimate the mycorrhizal dominance and associated belowground functions at large scales using remote sensing techniques. From a combination of chemical and spectral measurements on leaves of 32 European tree species forming either arbuscular (AM) or ectomycorrhizal (EM) symbiosis, we investigated the existence of “mycorrhizal optical types” and the leaf traits that may underpin them. Our results demonstrate that tree species associated with AM and EM fungi have distinct leaf colour and spectral fingerprints that can be linked to differences in leaf metabolism. In this talk, I will discuss the various factors that may have led to these spectral fingerprints as well as the potential and constraints of aboveground spectral signals acquired at the large scale to serve as optical surrogates of plant mycorrhizal associations and belowground function.
How to cite: Guzman, T., Féret, J.-B., Ogée, J., Petriacq, P., Gibon, Y., Valls-Fonayet, J., Dussarrat, T., Devert, N., Cassan, C., Flandin, A., and Wingate, L.: Is leaf spectral reflectance an integrator of mycorrhizal types?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8280, https://doi.org/10.5194/egusphere-egu25-8280, 2025.
Active forest restoration in tropical forests of Southeast Asia may alter mycorrhizal community structures with consequences for carbon sequestration at the ecosystem scale. While tropical rainforests are generally dominated by arbuscular mycorrhizal fungi, restoration efforts in Southeast Asia often entail the planting of tree species from the family Dipterocarpaceae (short: dipterocarps), which form associations with ectomycorrhizal fungi. With increased cover of dipterocarps, we expect a concomitant increase in ectomycorrhizal fungi and in turn altered forest biogeochemistry. In particular, an increase in the occurrence of ectomycorrhizal fungi could boost ecosystem carbon sequestration in actively restored compared to naturally regenerating forests via the suppression of decomposition belowground and enhancement of aboveground biomass. We tested this hypothesis at a restoration site in Sabah, Malaysian Borneo, which was selectively logged in the 1980s – 1990s and partly restored with enrichment planting and accompanying silvicultural interventions. In contrast to expectation, our results show that a higher density of trees forming symbioses with ectomycorrhizal fungi is associated with lower soil carbon stocks and altered biodiversity of soil fungi. These results highlight the need to better understand how active restoration of tropical rainforests may alter the net potential of these ecosystems to sequester carbon, and that fungi, not trees alone, can control carbon storage outcomes.
How to cite: Keller, N., Jilling, A., Koh, L. P., and Anthony, M. A.: The influence of active restoration of tropical rainforests on ecosystem carbon sequestration: potential links with ectomycorrhizal fungi, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3980, https://doi.org/10.5194/egusphere-egu25-3980, 2025.
Mycorrhizal associations drive plant community diversity and ecosystem functions. Arbuscular mycorrhiza (AM) and ectomycorrhiza (EcM) are two widespread mycorrhizal types and are thought to differentially affect plant diversity and productivity by nutrient acquisition and plant–soil feedback. However, it remains unclear how the mixture of two mycorrhizal types influences tree diversity at large spatial scales. Here, we explored these issues using data from 698 plots (400 m2 for each) across natural forests located in Southwest China. Both AM-dominated and EcM-dominated forests show relatively lower tree species richness, species evenness and Shannon diversity, whereas forests with the mixture of mycorrhizal strategies support more tree diversity. Interestingly, the impacts of EcM dominance depend on climate and soils. Our findings suggest that mycorrhizal dominance influences tree diversity in forest ecosystems.
How to cite: Ma, S.: Mycorrhizal dominance influences on forest tree diversity in Southwest China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21826, https://doi.org/10.5194/egusphere-egu25-21826, 2025.
Drought impacts soil organic carbon (SOC) cycling. Yet, there is limited understanding of how water limitation affects C inputs from rhizosphere, which contribute to new SOC formation while fueling soil microbial communities. We quantified C inputs and losses from roots and mycorrhizal fungi after two decades of irrigation in a dry Scots pine forest using 13C-enriched soil ingrowth bags. Fungal and bacterial communities in the ingrowth bags and in adjacent soils were analyzed by Illumina MiSeq sequencing.
In the first year, the new SOC formation was stimulated by water addition as compared to natural drought both in root-accessible (+25%) and mycorrhizal-accessible (+50%) bags. After two years, the overall new SOC formation was 5 times greater in root-accessible than in mycorrhizal-accessible bags. Although root ingrowth increased by 70% in root-accessible bags, the irrigation had a limited effect on the amount of new C accumulated in root-accessible and mycorrhizal-accessible bags. The lacking irrigation effect on net new SOC formation may relate to higher respiratory losses of new C, which agrees well with the observed increase by 55% in old C losses under irrigation. This suggests that enhanced C inputs by roots and mycorrhizal fungi were rapidly mineralized under irrigated conditions. Increased supply and turnover of rhizosphere C under irrigation were paralleled by shifts in fungal and bacterial communities in ingrowth bags as well as in adjacent soils. Accordingly, the presence of roots was a main driver of fungal and bacterial community structures in the ingrowth bags.
Overall, our results indicate that naturally dry conditions slow SOC cycling, suppressing rhizosphere C inputs as well as C losses. The reduced supply of belowground C leads to cascading effects on soil microbial community composition under drought.
How to cite: Guidi, C., Frey, B., Gavazov, K., Han, X., Peter, M., Meyer, M., Zhang, Y., Stierli, B., Brunner, I., and Hagedorn, F.: Drought reduces soil carbon inputs by roots and mycorrhizal fungi and alters soil microbial communities in a pine forest, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21141, https://doi.org/10.5194/egusphere-egu25-21141, 2025.
Droughts in forest ecosystems are a central concern for current and future biodiversity loss, carbon sequestration, and ecosystem functioning. Trees rely on symbiotic relationships with fungi to enhance nutrient uptake and improve stress tolerance, but the impacts of drought on plant-fungal relationships remain unclear and vary across different tree species compositions. This study investigated how inter- and intraspecific interactions among three prominent tree species in European forests—Fagus sylvatica (European beech), Quercus petraea (Sessile oak), and Tilia cordata (small-leaved lime)—shift under simulated drought conditions in relation to their rhizosphere fungal communities. We hypothesized that drought would shift the diversity and functional capacity of fungal communities, with these effects being dependent on the tree species and competitive context. To test this, we set up raised-bed experiments with seedlings of the three species as mono- or polycultures, exposing them to ambient rainfall conditions or two years of reduced precipitation using plastic roofing. We assessed tree seedling growth and development, and at the end of the experiment, we sampled rhizosphere soils from individual trees to characterize fungal diversity using full-length ITS DNA metabarcoding on an Oxford Nanopore Technology PromethION platform. Intraspecific versus interspecific competition provided more favourable conditions for tree growth under drought conditions. Our results show that fungal communities were responsive to variations in plant species, competitive context, and drought, and that fungal biodiversity explained unique patterns in plant growth responses to drought and competition, particularly for plant-symbiotic ectomycorrhizal fungi. This study highlights the variable effects of drought on fungal communities and underscores the importance of species-specific interactions in forest ecosystem responses to climate stress. These findings contribute to our understanding of the ecological role of fungi in forest species' resilience to climate change and may inform future forest management strategies aimed at mitigating the effects of drought in temperate regions.
How to cite: Papakoutis, C., Walde, M., Vitasse, Y., Zarsav, A., and Anthony, M.: Fungi and tree growth facilitation in European forests under drought conditions., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6078, https://doi.org/10.5194/egusphere-egu25-6078, 2025.
Fungi are among the most diverse ecological communities with distinct roles in mediating terrestrial biogeochemical cycles. Plant associated mycorrhizal fungi provide vital nutrients to host plants, but their ecological strategies vary across guilds. Ectomycorrhizal fungi associate with >60% of trees on Earth, possessing distinct capacities for decomposition, nutrient uptake, and soil exploration due to variation in their niches and distributions. Recently, we demonstrated the ectomycorrhizal fungal composition is linked to continental scale forest productivity across Europe. Differences in ectomycorrhizal fungal exploration types based on the quantity and composition of emanating hyphae and associated traits help explain this connection. What factors define and shape the ecological strategy of ectomycorrhizal fungal exploration can provide fundamental insight into their differential roles in forests. To address this, we compared genomic variation and modeled species distribution patterns of ectomycorrhizal fungal taxa from different exploration types. The exploration type concept has received considerable scrutiny because it can vary within an individual species, has not been sufficiently investigated across a wide range of taxa, and local distributional patterns often vary across disparate studies. These are important short comings of the exploration type trait that I will discuss. Despite limitations, we observe clear signatures of fungal exploration type in fully sequenced fungal genomes and in species distribution patterns across Europe. Our results emphasize that biomass production volume and rhizomorph formation are important sub-traits of exploration types. We further demonstrate that exploration types often merged into single exploration categories should be separated to observe distinct distributional patterns. Our results also provide insight into which ectomycorrhizal fungal traits are associated with forest nitrogen and phosphorus limitations and in turn overall forest productivity.
How to cite: Anthony, M., Mansfield, T., and Zarsav, A.: Variation in ectomycorrhizal fungal exploration types, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12007, https://doi.org/10.5194/egusphere-egu25-12007, 2025.
Mycorrhizal fungi are critical players in nutrient dynamics within forest ecosystems. Although typically associated with specific plant groups, evidence suggests that some species of ericoid mycorrhizal fungi can colonise ectomycorrhizal plants, and vice versa, with potential for nutrient exchange across these associations. Carbon (C) transfer from plants to mycorrhizal fungi and reciprocal nitrogen (N) transfer from fungi to plants are well-established processes. However, single studies report N loss from pine seedlings associated with mycorrhizal fungi and forest ground vegetation underscoring the complexity of these interactions.
Our study investigates whether such cross-functional colonisations may occur between Pinus sylvestris seedlings and Calluna vulgaris plants, and if they result in measurable N transfer, and evaluates the direction and magnitude of N movement between these plants and their mycorrhizal symbionts.
Therefore, we planted C. vulgaris plants in pots alongside 15N-labelled pine seedlings with varying degrees of interspecies connectivity: full root and hyphal contact, hyphal contact only, disrupted hyphal contact, and no contact. Some pots were enriched with additional nitrogen to assess the influence of nutrient availability on fungal-mediated nutrient transfer. Nitrogen transfer was quantified by measuring 15N content in roots and shoots of both species, as well as in fungal hyphae grown in ingrowth bags. To identify shared fungal taxa, we performed ITS sequencing on fungal communities associated with both C. vulgaris and pine roots.
To assess C exchange and hyphal connectivity, pine seedlings were 13C-labeled, allowing us to trace 13C allocation to fungal hyphae and C. vulgaris. Additionally, fungal biomass and enzyme activity were analysed to provide a detailed understanding of fungal contributions to nutrient dynamics.
In boreal forests, the field vegetation is frequently dominated by ericaceous dwarf shrubs, and their interactions with tree seedlings can therefore have far-reaching implications. This is particularly true if forest management practices change, for instance if the use of mechanical site preparation were to be reduced. Our study aims to elucidate the mechanisms underlying nitrogen and carbon fluxes in mixed ectomycorrhizal-ericaceous systems, providing insights into nutrient sharing and potential ecological implications in forest ecosystems.
How to cite: Danzberger, J. and Henriksson, N.: Nitrogen dynamics and mycorrhizal interactions between ectomycorrhizal and ericoid mycorrhizal plants, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8935, https://doi.org/10.5194/egusphere-egu25-8935, 2025.
Understanding the adaptations of terrestrial plants to water stress is crucial as climate change is already altering precipitation patterns. Mycorrhizal fungi enhance host water status through indirect mechanisms like nutrient uptake or plant osmoregulation. Direct water transport via fungal hyphae has also been demonstrated, but its exact contribution to total plant water uptake is still debated.
To demonstrate and quantify the direct transport of water from arbuscular mycorrhizal fungi (AMF) to its host plant, we utilized a plant mesocosm comprised of two compartments, separated by a porous membrane and an air gap. In the ‘plant-hyphae’ compartment, seedlings of microtomatoes were grown and inoculated with Rhizophagus irregularis. Hyphae, rather than plant roots, could cross the physical barrier of the porous membrane and the air gap to enter the ‘hyphae-only’ compartment. After several weeks of plant and hyphal growth, the ‘hyphae-only’ compartment was labelled with deuterated water (2H2O) and the isotopic composition of plant transpiration and soil water of both compartments were determined at different times after irrigation.
The presence of deuterated water in the plant transpiration stream confirmed that there was direct water transport via AMF hyphae to the plant. Previous studies have quantified the relative contribution of fungal-transported water by solving an isotope mass balance that includes the leaf transpired water and water extracted from soils of both ‘plant-hyphae’ and ‘hyphae-only’ compartments. This framework assumes that movement of deuterated water from the ‘hyphae-only’ to the ‘plant-hyphae’ compartment occurs only through fungal hyphae. However, we found that there was also diffusion of deuterated water vapour across the air gap separating the two compartments. This contamination led to overestimations of the relative contribution of AMF to total plant water uptake. After accounting for this contamination, the water contributed by AMF hyphae was quantified to 1% to 6% of total plant water uptake. Furthermore, using plant biomass as a weighing factor in the mixing model to account for differences in soil volume exploration by plant roots was critical for an accurate estimate of the contribution.
How to cite: Demullier, E., Ogée, J., Rambert-Banvillet, G., Arette-Hourquet, P., Zeng, M., Devert, N., Dong, Y., Ubierna, N., Fanin, N., Zheng, C., Guzman, T., and Wingate, L.: Arbuscular mycorrhizal contribution to plant water supply, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10489, https://doi.org/10.5194/egusphere-egu25-10489, 2025.
Communities in fire-affected ecosystems possess unique traits that aid survival and ecosystem recovery post-fire. As fires increase in frequency and intensity due to climate change, we enter a time increasingly influenced by fire therefore understanding the functions of these communities in forested systems is essential. While previous work has been done on the presence or absence of mycorrhizal fungi post-fire, generally using DNA-based approaches, there is limited knowledge about the functions they serve. This work aimed to identify functional traits of mycorrhizal fungi that correlate with fire regime and vegetative composition.
Thirty dry sclerophyll forest sites surrounding the Sydney basin that burned in the 2019-2020 black summer fires of Australia were selected based on historical gradients in fire severity and interval. Vegetative composition, fungal communities as well as soil carbon and nutrient availability were analysed from each site, from these, a subset of sites were selected for further study to distinguish direct (via effects on fire regimes) and indirect (via effects on nutrient availability) on mycorrhizal fungal functional traits associated with biomass production, hyphal chemistry (carbon, nitrogen, and phosphorus concentrations). For this, we harvested mycorrhizal fungal biomass using mesh in-growth bags filled with plastic resin-beads that absorb mineralized nutrients.
Available nutrients influenced mycorrhizal fungal community structure and biomass production in material collected from in-growth bags, whereas fire regime and vegetative structure had no effect. Hyphal chemistry was not significantly associated with nutrient availability, vegetative structure, or fire regime. In contrast, soil-derived data revealed significant effects of fire frequency on community structure, but no influence of nutrient availability or vegetative structure.
By integrating responses related to functional traits, fungal community composition, vegetation structure, and environmental factors, we aim to understand not only the functions that individual fungi provide in forested systems but also how these communities function collectively. We highlight the contrasting effects of fire frequency and nutrient availability on mycorrhizal communities in soil compared to those collected with mesh in-growth bags. These differences in community structure across sites likely reflect fungal growth strategies and their sensitivity to nutrient availability.
How to cite: Maerowitz-McMahan, S., Frew, A., Gordon, C., Nolan, R., and Powell, J.: From Ashes to Insights: Mycorrhizal Fungi Functions in Post-Fire Landscapes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15087, https://doi.org/10.5194/egusphere-egu25-15087, 2025.
Mycorrhizal fungal species are widespread across nearly all ecosystems worldwide and are generally found in symbiotic association with most plant species. In forested ecosystems, mycorrhizal fungi play a crucial role in facilitating plant nutrient acquisition and defending the plant from abiotic and biotic stress events, such as drought or pathogen attack.
We have recently shown that different tree species that associate with either arbuscular mycorrhizal (AM) fungi or ectomycorrhizal (EM) fungi exhibit distinct phytochemical differences, that might be linked to the type of fungal symbiont. In this study, we investigated the metabolic diversity of several ectomycorrhizal (EM) fungal species commonly found in forests, with the aim of linking their metabolic toolkits to functional processes important in forest ecosystems, such as soil respiration and enzyme activities.
In this presentation, we show that ectomycorrhizal fungi contain a diverse suite of metabolites (> 10000 metabolic features in the 5 species studied) composed largely of lipids and benzenoids with many of these metabolic features serving as reliable predictors that facilitate the distinction of different EM fungal species from one another.
We also present the results of a microcosm gas exchange experiment on the 5 EM fungal species grown under controlled temperature and CO₂ concentration conditions to investigate the link between fungal metabolic profiles and primary functions, such as respiration and enzymatic activity.
This research aims to deepen our understanding of plant-fungal symbioses in forests and the potential shifts in plant and fungal metabolism and function during interaction with one another and when exposed to changes in climate and atmospheric chemistry.
Arette-Hourquet P., Demullier E., Ogée J., Guzman T., Valls-Fonayet J. Petriacq P., Devert N., Ubierna N. Wingate L.
How to cite: Arette-Hourquet, P., Demullier, E., Guzman, T., Valls-fonayet, J., Devert, N., Ogée, J., Petriacq, P., Ubierna-lopez, N., and Wingate, L.: Investigating differences in the metabolomes of ectomycorrhizal fungi and their link to GHG fluxes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15545, https://doi.org/10.5194/egusphere-egu25-15545, 2025.
With forests covering roughly half of the Austrian land area, forest ecosystems have been monitored and characterized for centuries. While some aspects remain the same long-term, we are about to experience rapid changes due to climate change and loss of species. At the same time, emerging technologies like high throughput sequencing allow us to have deeper insights into the occurrence and diversity of species. For the hidden subsoil, metabarcoding of environmental DNA can uncover invisible soil life. This includes under-explored mycorrhizal fungi, especially species which do not regularly form fruiting bodies.
Supported by the Austrian biodiversity fund, the project „Zurück in die Zukunft“ (Back to the future) analyses archived forest soil samples from the past 32 years in order to capture diversity of ectomycorrhizal fungi. The dataset comprises samples from all federal states reaching from meadow forests of Pannonian regions to montane forests of the inner alps. Initial analyses detected >7000 fungal species, including >800 species of ectomycorrhizal fungi. The results provide an addition to already existing fungi databases of fruiting-body records. Fungal community composition is highly dependent on site-specific factors, which is thought to be explored using records of bio-geochemical data, vegetation and climate. By comparing the fungal communities of the 1990s, early 2000s and 2024, long-term changes and trends can be identified. The status of endangered species and potential neobiota in different habitats will be evaluated. We also aim to get a glance of future developments regarding forest ecosystems and their ecosystem functions.
How to cite: Ploderer, M., Hasenzangl, M., Dielacher, C., Erlbacher, K., Krisai-Greilhuber, I., Gorfer, M., Djukic, I., Kitzler, B., Michel, K., Reiter, R., and Berger, H.: Ectomycorrhiza: Back to the future, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16537, https://doi.org/10.5194/egusphere-egu25-16537, 2025.
Both clonal plant capabilities for physiological integration and common mycorrhizal networks (CMNs) formed by arbuscular mycorrhizal fungi (AMF) can influence the growth and insect resistance among interconnected individuals. Using a microcosm model system, we disentangled how CMNs interact with clonal integration to influence plant growth, development and herbivore defense. We grew Sphagneticola trilobata clones with isolated root systems in individual, adjacent containers while preventing, disrupting, or allowing clonal integration aboveground via spacers and belowground CMNs to form. We assessed multiple metrics of plant development, 15N transfer from donor (mother) to receiver (daughter) plants, variation in AMF communities, and changes in chemical defenses. We show that spacer formation between ramets and the capacity to form CMNs promoted and inhibited the growth of smaller, daughter plants, respectively. However, the effects on defense signals were inconsistent. When the two modes of interconnection co-occurred, CMNs significantly weakened promotion of daughter plants by clonal integration but enhanced the defense signal transmittance. AMF species richness was also negatively correlated with overall plant growth. Our results demonstrate that two common modes of plant interconnection interact in non-additive ways to affect clonal plant integration, growth and defense, questioning the underlying assumptions of the positive effects of both AMF CMNs and species richness in comparison to direct plant interconnections.
How to cite: Zhang, Y., Anthony, M., Chen, E., and Peng, S.: Growth and herbivore defense of clonal plants under single and combined modes of interconnection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3534, https://doi.org/10.5194/egusphere-egu25-3534, 2025.
Urban trees face numerous stress factors including de-icing salt in order to provide ecosystem services to cities. Mycorrhiza can mitigate environmental stresses but their role in mitigating urban specific stresses is not well known. We examined the effects soil chemistry on Tilia sp. planted along streets and it´s associated ectomycorrhiza. We compared park trees, trees from side streets, and trees from main streets with different salt stress levels . We show that 1) Tree vitality as well as ectomycorrhizal colonization decreases with increasing additions and sodium levels, 2) Tree vitality and colonisation as well at morphotype diversity were positively correlated to soil Mg. External mycelia production, measured with ingrowth bags was on the other hand higher in street trees than in parks and was not negatively correlated with Na but showed on the other hand a negative correlation to dissolved N. An explanation to the opposite patterns of colonization rate and production could be that the stressed environment causes high belowground turnover of roots and mycelia.
How to cite: Sandén, H., Rewald, B., Godbold, D., and Goff, D.: Effect of Urban Environmental Stress on Tree Vitality and ectomycorrhiza of Roadside Tilia sp., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20101, https://doi.org/10.5194/egusphere-egu25-20101, 2025.
