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Nutrient cycling in boreal forests : a mycological perspective : studies on phosphorus translocation within and between mycelia of saprotrophic- and mycorrhizal fungi

Lindahl, Björn (2001). Nutrient cycling in boreal forests : a mycological perspective : studies on phosphorus translocation within and between mycelia of saprotrophic- and mycorrhizal fungi. Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230
ISBN 91-576-6098-0
[Doctoral thesis]

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In order to understand the mechanisms controlling ecosystem diversity, production and responses to disturbance, improved knowledge about the movement and transformation of nutrients is essential. Most currently used models of nutrient cycling in boreal forests have been developed with agricultural ecosystems in mind. Boreal forest ecosystems are characterised by a high abundance and diversity of basidiomycetous fungi. These fungi occur rarely in agricultural soils but play a pivotal role in boreal forests as decomposers of organic matter and symbiotic associates of plants. The ecophysiology of basidiomycetous fungi has to be considered, when constructing nutrient cycling models for boreal ecosystems. Decomposer fungi and symbiotic mycorrhizal fungi have traditionally been placed in distinct functional categories and treated separately. This separation has no phylogenetic justification however, and fungi from the two groups share a similar mycelial morphology as well as the same microsites on the forest floor. This thesis describes experiments in which radioactive phosphorus was used in combination with non-destructive electronic autoradiography to study nutrient translocation in soil microcosms containing saprotrophic- and ectomycorrhizal fungi. Bidirectional phosphorus translocation in fungal rhizomorphs was observed, showing that nutrients may circulate throughout basidiomycetous mycelia, enabling net translocation from sources to sinks. Studies of mycelial interactions between ectomycorrhizal fungi and saprotrophic fungi suggested that ectomycorrhizal fungi can interact antagonistically with other soil fungi. Interactions were associated with transfer of significant amounts of phosphoms between the interacting mycelia. Ectomycorrhizal fungi were able to mobilise radioactive phosphorus from labelled saprotrophic mycelium and to transfer the acquired phosphoms to their host plants. Wood decomposing fungi were similarly able to mobilise phosphoms from mycorrhizal mycelium and to translocate the acquired phosphoms to colonised wood blocks. The net direction and rate of phosphoms transfer between interacting mycelia was shown to depend on the availability of resources to the interacting fungi. To explain the observed phosphoms transfer it is hypothesised that interacting basidiomycetous fungi may obtain nutrients by killing and degrading each other’s mycelia. This highly competitive foraging behaviour, in combination with the ability to translocate resources over considerable distances, makes basidiomycetous fungi well adapted to the spatial heterogeneity and low nutrient availability of the boreal forest floor. A new model of nutrient cycling in boreal forests is proposed that allows for nutrient retention in soil fungi and intense competition for nutrients between soil organisms. Symbiotic association with ectomycorrhizal fungi that can effectively compete with other soil organisms for organic nutrient sources, enables plants to acquire nutrients without the need for large scale nutrient mineralisation.

Authors/Creators:Lindahl, Björn
Title:Nutrient cycling in boreal forests : a mycological perspective : studies on phosphorus translocation within and between mycelia of saprotrophic- and mycorrhizal fungi
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Silvestria
Year of publishing :2001
Number of Pages:48
Publisher:Swedish University of Agricultural Sciences
ISBN for printed version:91-576-6098-0
Publication Type:Doctoral thesis
Article category:Other scientific
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Keywords:basidiomycete, ectomycorrhiza, wood rotting fungi, translocation, mycelial interaction, microcosm, autoradiography, phosphorus, nutrient cycling, Hypholoma fasciculare, Suillus variegatus, Paxillus involutus, Pinus sylvestris
Permanent URL:
ID Code:17742
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: SLUpub Connector
Deposited On:07 Oct 2020 11:59
Metadata Last Modified:26 Oct 2020 13:47

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