Functional diversity of mycorrhiza in relation to land-use changes and ecosystem functions

Experimental approaches to obtain information on substrate preferences of ectomycorrhizal fungi under field conditions are scarce.  Based on the results of the previous phases, the specific aims of this project are:

1. To dissect temporal and spatial turnover of root-associated fungal assemblages according to ecological groups (symbiotroph, saprotroph, pathotroph) and their main drivers (land use, climate, abiotic soil conditions, and root nutrients)
2. To examine fungal traits for nutrient use by bait experiments
3. To establish causal relationships between forest management measures (tree cutting and gap formation) between the function and composition of root-associated fungi and root nutrient physiology

To achieve these goals, we will sample roots in 150 forest plots of the Biodiversity Exploratories and use the results from 2014, 2017 and 2020 to analyse spatiotemporal variation of fungi on roots. In bait experiments, mesh containers accessible for fungal hyphae, will be supplemented with substrates and the colonising fungal community will be studied. Tree cutting affects carbon allocation to the soil. We will use the new forest experiment (tree cutting) to examine the impact of changes in root carbon physiology on the structure of associated ectomycorrhizal, saprotrophic and other fungal groups and the feedback for tree mineral nutrition. These results will contribute towards to increasing our understanding of ecosystem functioning.

1. The role of root-associated fungi for beech adaptability and adaptedness

Fungal assembly plays a pivotal role in shaping ecosystem functioning, with direct implications for forest resilience, carbon sequestration, and nutrient cycling. In European beech (Fagus sylvatica) forests, seedlings from different population exhibit low ecological adaptedness, indicating limited specialization to local conditions. However, the beech progenies show high adaptability, with most populations maintaining performance across diverse environments. This suggests that mixed planting of local and climate-matched non-local populations can enhance forest resilience under climate change. Crucially, root-associated fungi significantly influence seedling biomass, primarily through nitrogen uptake, which accounts for over 60% of biomass variation. Mycorrhizal fungal species promote growth, while saprotrophic fungi negatively affect it. This functional divergence underscores the importance of managing not just tree genetics but also beneficial microbial associations in reforestation and forest conversion projects.

Further reading: Pena et al. 2026

2. Soil fungi contribute to C sequestration on mineral surfaces

In soil carbon dynamics, fungal communities on mineral surfaces are key drivers of mineral-associated organic matter (MAOM) formation, a critical mechanism for long-term carbon stabilization. Goethite (iron oxide) accumulates significantly more carbon than illite (clay), regardless of land use or management intensity. Fungal community assembly on mineral surfaces is strongly influenced by mineral type, with saprotrophic fungi dominating on mineral substrates. However, environmental filters such as soil chemistry, tree species, and regional climate exert stronger control over community structure than mineral type alone. A shift from saprotrophic to ectomycorrhizal fungi is linked to enhanced nutrient acquisition, indicating functional transitions in the mineralosphere. This highlights the dynamic interplay between fungal trophic groups and mineral surfaces in nutrient cycling.

Further reading: Brand et al. 2024, Bramble et al. 2026

3. Fungal-mediated root nutrient acquisition in grasslands and forests is shaped by nutrient form and habitat filters

In grasslands, substrate quality shapes hyphosphere microbial assembly: root litter promotes saprotrophic fungi and bacteria involved in decomposition, enhancing fungal biomass and carbon incorporation, but less efficiently transfers nitrogen to plants than labile substrates like arginine. This suggests a key role for fungal-fungal interactions—particularly between arbuscular mycorrhizal (AM) fungi and saprotrophs—in modulating organic nitrogen availability.

Further reading: Brand et al. 2025

In forests, fine root biomass increases with soil moisture and fertility but declines under high management intensity. Under drought, roots accumulate osmolytes like glucose, indicating a trade-off between growth and drought tolerance. As potassium may contribute to drought tolerance, the results support exploring potassium supplementation as a strategy to mitigate drought stress.

Further reading: Yang et al. 2025

Conclusions

Practical applications include: (1) using climate-adaptive beech populations with microbial inoculation to boost seedling growth; (2) prioritizing oxide-rich soils for carbon sequestration through sustainable land use; (3) managing grasslands to enhance fungal networks that improve nutrient cycling; and (4) integrating microbial and nutrient management into forest adaptation strategies. These insights highlight the need for holistic, microbiome-informed ecosystem management.