Fungal ecology in boreal forest ecosystems

Lindahl, Björn D.; Clemmensen, Karina E.

doi:10.1002/9781118951446.ch21

Cited by 17 publications

(21 citation statements)

References 77 publications

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“…These activities, in turn, have a major effect on the environment through feedback loops that may either stabilize ecosystems or lead to directional development. Fungal species are central mediators of these interactions (Lindahl and Clemmensen, 2016). In species, response traits (that determine population responses to environmental changes) are connected to effect traits (that determine how communities influence their environment; Koide et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands

et al. 2017

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Forestry reshapes ecosystems with respect to tree age structure, soil properties and vegetation composition. These changes are likely to be paralleled by shifts in microbial community composition with potential feedbacks on ecosystem functioning. Here, we assessed fungal communities across a chronosequence of managed Pinus sylvestris stands and investigated correlations between taxonomic composition and extracellular enzyme activities. Not surprisingly, clear-cutting had a negative effect on ectomycorrhizal fungal abundance and diversity. In contrast, clear-cutting favoured proliferation of saprotrophic fungi correlated with enzymes involved in holocellulose decomposition. During stand development, the re-establishing ectomycorrhizal fungal community shifted in composition from dominance by Atheliaceae in younger stands to Cortinarius and Russula species in older stands. Late successional ectomycorrhizal taxa correlated with enzymes involved in mobilisation of nutrients from organic matter, indicating intensified nutrient limitation. Our results suggest that maintenance of functional diversity in the ectomycorrhizal fungal community may sustain long-term forest production by retaining a capacity for symbiosis-driven recycling of organic nutrient pools.

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Section: Discussionmentioning

confidence: 99%

Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands

et al. 2017

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“…melanin) and antibiotics (Burdon, 2001;Lehmann and Kleber, 2015). Saprotrophic fungi might commonly encounter metabolic C limitations, particularly in the deeper layers of the soil that, in comparison with fresh litter, contain more decomposed and oxidized SOM (Lindahl et al, 2007;Lindahl and Clemmensen, 2016). However, the situation is different for ECM fungi, which receive their energy from the host plants.…”

Section: Discussionmentioning

confidence: 99%

“…Fungi are the key SOM-processing microorganisms in boreal forest ecosystems (Lindahl et al, 2007;Lindahl and Clemmensen, 2016). These ecosystems contain ca.…”

Section: Introductionmentioning

confidence: 99%

“…Filamentous saprotrophic fungi that belong to the class Basidiomycetes possess a unique ability to degrade lignin and other phenolic compounds found in the forest litters (Baldrian, 2008). In deeper soil layers that are enriched with more pronouncedly decomposed and oxidized SOM, saprotrophic fungi cannot efficiently acquire C needed for growth and they are taken over by ectomycorrhizal (ECM) fungi, which obtain their energy from the host plants (Lindahl et al, 2007;Lindahl and Clemmensen, 2016). In exchange, the ECM fungi supply the host plants with nutrients, such as N. Even though ECM fungi have lost many genes encoding lignocellulose-degrading enzymes that are present in saprotrophic fungi (Kohler et al, 2015), recent laboratory studies have shown that they can use oxidative mechanisms to decompose and acquire N from SOM in the presence of an easily available energy source (i.e., glucose) (Rineau et al, 2012;Shah et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Mineral surface‐reactive metabolites secreted during fungal decomposition contribute to the formation of soil organic matter

Wang

Tian

Bengtson

et al. 2017

Environmental Microbiology

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Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view is that oxidation and depolymerization of SOM by microorganisms promote the formation of SOM-mineral associations that is critical for SOM stabilization. To test this hypothesis, we performed laboratory-scale experiments involving one ectomycorrhizal and one saprotrophic fungus that represent the two major functional groups of microbial decomposers in the boreal forest soils. Fungal decomposition enhanced the retention of SOM on goethite, partly because of oxidative modifications of organic matter (OM) by the fungi. Moreover, both fungi secreted substantial amounts (> 10% new biomass C) of aromatic metabolites that also contributed to an enhanced mineral retention of OM. Our study demonstrates that soil fungi can form mineral-stabilized SOM not only by oxidative conversion of the SOM but also by synthesizing mineral surface-reactive metabolites. Metabolites produced by fungal decomposers can play a yet overlooked role in the formation and stabilization of SOM.

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“…Besides saprotrophic fungi, ECM fungi are the major functional group of fungi in boreal forest ecosystems (12). ECM fungi obtain their energy (i.e., glucose) from their host plants, and the mycelium is mainly located in deeper soil horizons that are enriched in decomposed and oxidized SOM (13).…”

Section: Introductionmentioning

confidence: 99%

Influence of Ammonium on Formation of Mineral-Associated Organic Carbon by an Ectomycorrhizal Fungus

Wang

Tian

Tunlid

et al. 2019

Appl Environ Microbiol

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The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-reactive metabolites (in vivo pathway). In this study, we examined how changes in nitrogen (N) availability affected the formation of mineral-associated carbon (C) from these two pathways. DOM was extracted from forest soils. The processing of this DOM by the ectomycorrhizal fungus Paxillus involutus was examined in laboratory-scale studies with different levels of ammonium. At low levels of ammonium (i.e., under N-limited conditions), the DOM components were slightly oxidized, and fungal C metabolites with iron-reducing activity were secreted. Ammonium amendments decreased the amount of C metabolites, and no additional oxidation of the organic matter was detected. In contrast, the hydrolytic activity and the secretion of N-containing compounds increased, particularly when high levels of ammonium were added. Under these conditions, C, but not N, limited fungal growth. Although the overall production of mineral-associated organic C was not affected by ammonium concentrations, the observed shifts in the activities of the ex vivo and in vivo pathways affected the composition of organic matter adsorbed onto the mineral particles. Such changes will affect the properties of organic matter-mineral associations and, thus, ultimately, the stabilization of SOM. IMPORTANCE Nitrogen (N) availability plays a critical role in the cycling and storage of soil organic matter (SOM). However, large uncertainties remain in predicting the net effect of N addition on soil organic carbon (C) storage due to the complex interactions between organic matter, microbial activity, and mineral particles that determine the formation of stable SOM. Here, we attempted to disentangle the effects of ammonium on these interactions in controlled microcosm experiments including the ectomycorrhizal fungus P.involutus and dissolved organic matter extracted from forest soils. Increased ammonium levels affected the fungal processing of the organic material as well as the secretion of extracellular metabolites. Although ammonium additions did not increase the net production of mineral-adsorbed C, changes in the decomposition and secretion pathways altered the composition of the adsorbed organic matter. These changes may influence the properties of the organic matter-mineral associations and, thus, the stabilization of SOM.

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Fungal ecology in boreal forest ecosystems

Cited by 17 publications

References 77 publications

Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands

Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands

Mineral surface‐reactive metabolites secreted during fungal decomposition contribute to the formation of soil organic matter

Influence of Ammonium on Formation of Mineral-Associated Organic Carbon by an Ectomycorrhizal Fungus

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