Data from: Comparison of carbon and nitrogen accumulation rate between bog and fen phases in a pristine peatland with the fen-bog transition

Long-term carbon and nitrogen dynamics in boreal peatlands are affected by
both vegetation production and decomposition processes. Here, we examined
the carbon accumulation rate (CAR), nitrogen accumulation rate (NAR) and
δ13C, δ15N of plant residuals in a peat core dated back to ~8500 cal yr BP
in a temperate peatland in Northeast China. Impacted by the tephra during
1160 and 789 cal yr BP and climate change, the peatland changed from a fen
dominated by vascular plants to a bog dominated by Sphagnum mosses. We
used the Clymo model to quantify peat addition rate and decay constant for
acrotelm and catotelm layers during both bog and fen phases. Our studied
peatland was dominated by Sphagnum fuscum during the bog phase (789 ~ -59
cal yr BP) and lower accumulation rates for the upper sections in the
acrotelm layer during this phase, suggesting the dominant role of volcanic
eruption in the CAR of the peat core. Both mean CAR and NAR were higher
during the bog phase than during the fen phase in our study, consistent
with the results of the only one similar study in the literature. Because
the input rate of organic matter was considered to be lower during the bog
phase, the decomposition process must have been much lower during the bog
phase than during the fen phase and potentially controlled CAR and NAR.
During the fen phase, CAR was also lower under higher temperature and
summer insolation, conditions beneficial for decomposition. δ15N of
Sphagnum hinted that nitrogen fixation had positive effect on nitrogen
accumulation, particular in recent decades. Our study suggested that
decomposition is more important for carbon and nitrogen sequestration than
production in peatlands in most conditions and if future climate changes
or human disturbance increase decomposition rate, carbon sequestration in
peatlands will be jeopardized.