Abstract

In boreal ecosystems plant production is often limited by low availability of nitrogen. Nitrogen retention in below-ground organic pools plays an important role in restricting recirculation to plants and thereby hampers forest production. Saprotrophic fungi are commonly assigned to different decomposer strategies, but how these relate to nitrogen cycling remains to be understood. Decomposition of Scots pine needle litter was studied in axenic microcosms with the ligninolytic litter decomposing basidiomycete Gymnopus androsaceus or the stress tolerant ascomycete Chalara longipes. Changes in chemical composition were followed by C-13 CP/MAS NMR spectroscopy and nitrogen dynamics was assessed by the addition of a N-15 tracer. Decomposition by C. longipes resulted in nitrogen retention in non-hydrolysable organic matter, enriched in aromatic and alkylic compounds, whereas the ligninolytic G. androsaceus was able to access this pool, counteracting nitrogen retention. Our observations suggest that differences in decomposing strategies between fungal species play an important role in regulating nitrogen retention and release during litter decomposition, implying that fungal community composition may impact nitrogen cycling at the ecosystem level.

Keywords

saprotrophic fungi; litter decomposition; C-13 CP/MAS NMR; nitrogen cycling; N-15 tracer; functional guilds

Published in

FEMS Microbiology Ecology
2019, volume: 95, number: 6, article number: fiz059
Publisher: OXFORD UNIV PRESS

Authors' information