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Litter decomposing fungi in boreal forests

their function in carbon and nitrogen circulation

Boberg, Johanna (2009). Litter decomposing fungi in boreal forests. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2009:75
ISBN 978-91-576-7422-7
[Doctoral thesis]

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Decomposition of soil organic matter connects the global carbon (C) cycle with the turnover of nitrogen (N), but exactly how the availability of N affects the soil C turnover is unclear. In boreal forest soils, fungi are essential to litter decomposition. Most litter decomposing fungi form large mycelia and have a well developed capacity to translocate resources, such as carbohydrates and nutrients, within their mycelia. Translocation by litter fungi may enable efficient utilization of spatially separated substrates differing in respect to their quality and thus have a major influence on decomposition and nutrient dynamics. In order to isolate the different mechanisms controlling C and N turnover by litter decomposing fungi, controlled laboratory studies were conducted with the known, common litter fungi Marasmius androsaceus and Mycena epipterygia. Furthermore, some litter fungi with unknown functional capability were tested for their ability to decompose pine needles and potential effects of interspecific interactions for C and N dynamics were also assessed. The low initial N content of recently abscised pine needles limited the catabolism as well as growth and needle decomposition by both M. androsaceus and M. epipterygia. Accordingly, when colonizing new needle litter both fungi translocated assimilated N into the needles leading to a net gain in the total N pool. This way, both fungi were able to increase their growth in the new substrate. In addition, both fungi translocated C to low C:N ratio substrates, thereby overcoming local C deficiency and subsequently restricted mineralization of N. When able to connect substrates of different quality, both fungi increased their efficiency by allocating a larger proportion of assimilated C into biomass production, thereby reducing the release of CO₂. Interspecific antagonistic interactions prevented mycelial linking of substrates colonized by different species, and thereby hampered translocation. This thesis demonstrates that the capacity of litter decomposing fungi to translocate resources within their mycelia may have a decisive influence on the C and N cycle in boreal forests.

Authors/Creators:Boberg, Johanna
Title:Litter decomposing fungi in boreal forests
Subtitle:their function in carbon and nitrogen circulation
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2009
Number of Pages:67
ALLI. Boberg, J., Finlay, R.D., Stenlid, J., Näsholm, T., Lindahl, B.D. (2008). Glucose and ammonium additions affect needle decomposition and carbon allocation by the litter degrading fungus Mycena epipterygia. Soil Biology & Biochemistry 40, 995-999. II. Boberg, J.B., Finlay, R.D., Stenlid, J., Lindahl, B.D. (2009). Fungal C translocation restricts N-mineralization in heterogeneous environments. Functional Ecology, doi 10.1111/j.1365-2435.2009.01616.x III. Boberg, J.B., Ihrmark, K., Lindahl, B.D. Decomposing capacity of some ascomycetes common in Pinus sylvestris needle litter. (manuscript). IV. Boberg, J.B., Finlay, R.D., Stenlid, J., Ekblad, A., Lindahl, B.D. Fungal reallocation of nitrogen during litter decomposition in stratified systems. (manuscript).
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7422-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:fungi, marasmius, mycena, forest litter, degradation, translocation, nitrogen, carbon, cycling, boreal forests, pinus sylvestris, forest soils, soil organic matter, sweden
Keywords:C cycling, C-use efficiency, fungal translocation, litter decomposing fungi, Marasmius androsaceus, Mycena epipterygia, N cycling, N-mineralization, Pinus sylvestris
Permanent URL:
ID Code:2136
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Johanna Boberg
Deposited On:16 Oct 2009 00:00
Metadata Last Modified:02 Dec 2014 10:16

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