Insights into carbon and nitrogen dynamics of mycorrhizal and saprotrophic fungi from isotopic evidence
Hobbie EA, Macko SA, Shugart HH. 1997. Insights into carbon and nitrogen dynamics of mycorrhizal and saprotrophic fungi from isotopic evidence. Bulletin of the Ecological Society of America. 78(4):109
The successful use of natural abundances of carbon and nitrogen isotopes in the study of ecosystem dynamics suggests that isotopic measurements could give new insights into fungal functioning in nitrogen and carbon cycling. Along a successional sequence in Glacier Bay National Park, Alaska, sporocarps of mycorrhizal and saprotrophic fungi, vegetation,and soils were collected in young, deciduous-dominated sites and older, coniferous-dominated sites for isotopic analysis. For both carbon and nitrogen, foliage and organic soils were isotopically depleted relative to both fungal types. Mycorrhizal fungi were higher in 15N and lower in 13C than saprotrophs. The apparent fractionation by mycorrhizal fungi during the transfer of nitrogen to plants is attributed to transamination reactions within the mycorrhizae. Mycorrhizal taxa with highly enriched nitrogen signatures may be especially important as nitrogen suppliers to host plants. Carbon signatures of mycorrhizal fungi are higher than foliage because the fungi use isotopically enriched photosynthate such as simple sugars, in contrast to the mixture of lignins, cellulose and sugars in leaves. A similar trend between saprotrophs and wood suggests that lignin is unimportant as a carbon source to these fungi. Isotopes appear to be a powerful tool to probe the fungal role in ecosystem processes.
- Type
- Journal Article
- Authors
- Hobbie, Erik; Macko, S; Shugart, H
- Units
- GLBA
- Keywords
- Glacier Bay