Journal
PLANT AND SOIL
Volume 438, Issue 1-2, Pages 19-38Publisher
SPRINGER
DOI: 10.1007/s11104-019-03958-6
Keywords
Dissolved organic carbon; C-13; Peatland; Root carbon input; Soil respiration; Sedges; Shrubs; Vascular plants
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Funding
- TU Dresden
- Wageningen University
- University of Amsterdam
- University of Ferrara (FAR 2014)
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AimsNorthern peatlands store large amounts of soil organic carbon (C) that can be very sensitive to ongoing global warming. Recently it has been shown that temperature-enhanced growth of vascular plants in these typically moss-dominated ecosystems may promote microbial peat decomposition by increased C input via root exudates. To what extent different plant functional types (PFT) and soil temperature interact in controlling root C input is still unclear. In this study we explored how root C input is related to the presence of ericoid shrubs (shrubs) and graminoid sedges (sedges) by means of a factorial plant clipping experiment (= PFT effect) in two peatlands located at different altitude (= temperature effect).MethodsBy selective clipping of shrub and sedge shoots in mixed vegetation at two Alpine peatland sites we interrupted the above- to belowground translocation of C, thus temporarily inhibiting root C release. Subsequent measurements of soil respiration, dissolved organic carbon (DOC) concentration and stable isotope composition (C-13) of DOC in pore water were used as proxies to estimate the above- to belowground transfer of C by different PFT.ResultsWe found that soil respiration rates and DOC concentrations temporarily decreased within 24h after clipping, with the decrease in soil respiration being most pronounced at the 1.4 degrees C warmer peatland after clipping shrubs. The transient drop in DOC concentration coincided with a shift towards a heavier C isotope signature, indicating that the decrease was associated with inhibition of a light C source that we attribute to root exudates. Together these results imply that shrubs translocated more C into the peat than sedges, particularly at higher temperature.ConclusionsWe showed that plant functional type and temperature interact in controlling root C input under field conditions in peatlands. Our results provide a mechanistic evidence that shrubs may potentially promote the release of stored soil C through root-derived C input.
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