Increasing abundance of soil fungi is a driver for N-15 enrichment in soil profiles along a chronosequence undergoing isostatic rebound in northern Sweden
2009 (English)In: Oecologia, ISSN 0029-8549, Vol. 160, no 1, 87-96 p.Article in journal (Refereed) Published
Soil organic material (SOM) is usually enriched in N-15 in deeper soil layers. This has been explained by discrimination against the heavier isotope during decomposition or by the accumulation of N-15-enriched microbial biomass versus plant biomass in older SOM. In particular, ectomycorrhizal (EM) fungi have been suggested to accumulate in old SOM since this group is among the most N-15-enriched components of the microbial community. In the present study we investigated the microbial community in soil samples along a chronosequence (7,800 years) of sites undergoing isostatic rebound in northern Sweden. The composition of the microbial community was analyzed and related to the delta N-15 and delta C-13 isotope values of the SOM in soil profiles. A significant change in the composition of the microbial community was found during the first 2,000 years, and this was positively related to an increase in the delta N-15 values of the E and B horizons in the mineral soil. The proportion of fungal phospholipid fatty acids increased with time in the chronosequence and was positively related to the N-15 enrichment of the SOM. The increase in delta C-13 in the SOM was much less than the increase in delta N-15, and delta C-13 values in the mineral soil were only weakly related to soil age. The C:N ratio and the pH of the soil were important factors determining the composition of the microbial community. We suggest that the N being transported from the soil to aboveground tissue by EM fungi is a driver for N-15 enrichment of soil profiles.
Place, publisher, year, edition, pages
2009. Vol. 160, no 1, 87-96 p.
IdentifiersURN: urn:nbn:se:umu:diva-23306DOI: 10.1007/s00442-008-1270-0OAI: oai:DiVA.org:umu-23306DiVA: diva2:222765