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Influence of fungi on N and C dynamics during organic matter decomposition in boreal forests

Baskaran, Preetisri (2017). Influence of fungi on N and C dynamics during organic matter decomposition in boreal forests. Diss. (sammanfattning/summary) Uppsala, Sweden : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2017:61
ISBN 978-91-7760-012-1
eISBN 978-91-7760-013-8
[Doctoral thesis]

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Soils in terrestrial ecosystems store more carbon (C) than plants and the atmosphere combined, and ecosystems’ C dynamics are strongly dependent of nitrogen (N) availability. Moreover, plant production in boreal ecosystems is often limited by low N availability, and N retention in soils is a major constraint on N recirculation to plants. Soil fungi strongly influence C and N interactions in boreal ecosystems. However, a better knowledge of their role in the C and N interactions and balances is required. In this work we address this question with modelling and experimental approaches and explore impacts of fungi on C and N balances during soil organic matter decomposition in boreal ecosystems. We developed a biogeochemical model of C and N flows between plants, soil organic matter (SOM), saprotrophs, ectomycorrhizal (ECM) fungi, and inorganic N stores to predict the effects of ECM fungi decomposition on plant production and soil C sequestration. Model-based qualitative investigations on plant-mycorrhizal symbiosis were performed to improve our understanding of the mutualistic-parasitic continuum of ECM fungi’s relationships with plants. Under controlled laboratory conditions microcosms were set up with saprotrophic fungi (Gymnopus androsaceus and Chalara longipes) to explore saprotrophic fungi’s influence on soil N retention and changes in microbial carbon use efficiency (CUE) during decomposition. The model-based analysis indicated that under low-N conditions, increased ECM decomposition promotes plant growth but decreases soil C storage. Further, the model analysis indicated that the mutualistic-parasitic continuum between plant and the mycorrhiza depended on the rates of C allocation from the plant to ECM fungi. The experimental observation showed that both G. androsaceus and C. longipes incorporated N into the non-hydrolysable fraction, but with a relatively higher N incorporation in the latter. Overall, this thesis highlights that soil C storage in boreal forests is regulated by the relationship between plant and ECM fungi and this relationship depends on the partitioning of decomposition between saprotrophs and ECM fungi. This work shows that differences in decomposing strategies between two saprotrophic fungi play an important role in N retention during litter decomposition. In addition, we propose that better methods to evaluate CUE could improve predictions of C and N dynamics in ecosystem models. Taken together, I suggest that enhanced knowledge about the functional properties of soil fungi and incorporating different fungal traits into ecosystem models could significantly improve predictions of ecosystem responses to environmental changes.

Authors/Creators:Baskaran, Preetisri
Title:Influence of fungi on N and C dynamics during organic matter decomposition in boreal forests
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :26 July 2017
Depositing date:1 August 2017
Number of Pages:72
IBaskaran, P., Hyvönen, R., Berglund, L., Clemmensen, K.E., Ågren, G.I., Lindahl, B.D. and Manzoni, S. (2016). Modelling the influence of ectomycorrhizal decomposition on plant nutrition and soil carbon sequestration in boreal forest ecosystems. New Phytologist, 213:1452-1465.
IIÅgren, G.I., Hyvönen, R. and Baskaran, P. Mycorrhiza, friend or foe? (manuscript)
IIIBaskaran, P., Ekblad, A., Soucemarianadin, L., Hyvönen, R., Schleucher, J. and Lindahl, B.D. N stabilisation during decomposition of boreal forest litter (manuscript).
IVBaskaran, P., Ekblad, A., Lindahl, B.D. and Herrmann, A. A reductionist approach to evaluate carbon use efficiency of a litter-decomposing fungus after glucose and nitrogen additions (manuscript).
Place of Publication:Uppsala, Sweden
Publisher:Department of Ecology, Swedish University of Agricultural Sciences.
ISBN for printed version:978-91-7760-012-1
ISBN for electronic version:978-91-7760-013-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:K Forestry > K01 Forestry - General aspects
P Natural resources > P34 Soil biology
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Agrovoc terms:soil fungi, degradation, carbon, nitrogen, ecosystems, boreal forests, ectomycchizae, efficiency
Keywords:fungal mediated decomposition, nutrient cycling, soil organic matter dynamics, plant nutrition, CUE
Permanent URL:
ID Code:14475
Faculty:S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
External funders:FORMAS
Deposited By: Ms Preetisri Baskaran
Deposited On:02 Aug 2017 08:44
Metadata Last Modified:09 Sep 2020 14:17
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