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2048216 
Journal Article 
Glucose and ammonium additions affect needle decomposition and carbon allocation by the litter degrading fungus Mycena epipterygia 
Boberg, J; Finlay, RD; Stenlid, Jan; Nasholm, T; Lindahl, BD 
2008 
1 
Soil Biology and Biochemistry
ISSN: 0038-0717
EISSN: 1879-3428 
PERGAMON-ELSEVIER SCIENCE LTD 
OXFORD 
40 
4 
995-999 
WOS:000254098000015 
Saprotrophic microorganisms in soils have traditionally been assumed to be carbon (C) limited, since additions of readily assimilable carbohydrates usually result in increased respiration. In many forest soils, however, rapid nitrogen (N) immobilization and increased microbial growth in response to N addition indicate N limitation. Here we test whether this apparent contradiction could be explained by changes in C allocation between microbial growth and respiration (i.e. changed C-use efficiency) under controlled conditions in laboratory microcosms. Respiration, mycelial production and needle mass loss were monitored after application of glucose or ammonium sulphate to Pinus sylvestris needles inoculated with the litter decomposer fungus Mycena epipterygia. Addition of ammonium resulted in a 32% increase in respiration, 31% increase in needle mass loss and increased mycelial production, indicating that both growth and activity of the fungus were N limited. In spite of N limitation, additions of glucose resulted in a 19% increase in respiration but had no effect on mycelial production and led to a 17% decrease in needle mass loss, indicating a reduced C-use efficiency of the fungus. The capacity of individual fungi to adapt their C-use efficiency to C availability implies that additions of labile C could increase respiration even under N-limited conditions. (C) 2007 Elsevier Ltd. All rights reserved. 
nutrient cycling; litter decomposition; respiration; fungal biomass; Pinus sylvestris; C-use efficiency; C limitation; N limitation