期刊
OECOLOGIA
卷 160, 期 1, 页码 87-96出版社
SPRINGER
DOI: 10.1007/s00442-008-1270-0
关键词
Microbial community; PLFA; Chronosequence; Soil profile; Ectomycorrhizal fungi
类别
资金
- Carl Trygger Foundation
- Swedish Research Council for the Environment, Agricultural Sciences and Spatial Planning (Formas)
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.
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