In the present study, we investigated the impacts of root
exudate stoichiometry on microbial processes and soil C dynamics
in two adjacent forests: a
70 year-old dragon spruce (Picea
asperata) plantation (hereafter spruce plantation) characterized by
low soil N, and a
200 year-old forest dominated by spruce (P.
asperata) and
fir (Abies faxoniana) (hereafter spruce-fir) character-
ized by high soil N. Because the forests have underlying soils,
differences in soil N availability between the two forests provided a
unique opportunity to examine whether N availability influences
the impacts of exudate additions on SOM decomposition. The aim
of this study was to investigate the degree to which priming effects
depend on substrate stoichiometry, N availability, and microbial
communities, by adding exudate mimics to
field soils. We
hypothesized that losses of soil organic C owing to exudate
addition (i.e., priming effects) would be greatest in spruce
plantation soils with the lowest soil N (e.g., plantation soils
receiving C only) and least in spruce-fir soils with the highest soil N
(e.g., spruce-fir soils receiving N).