Publication Date:
2014-01-19
Description:
[1] Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6 ºC) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha -1 yr -1 , respectively) over 12 years of field treatments in a boreal mire. An empirical mass-balance model was applied to 210 Pb dated peat cores to evaluate changes in C inputs, C mass-loss and net C accumulation rates in response to the treatments. We found that: i) none of the treatments generated a significant effect on peat mass-loss decay rates, ii) C input rates were positively affected by N additions and negatively affected by S additions, iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.
Print ISSN:
0148-0227
Topics:
Biology
,
Geosciences
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