期刊
GLOBAL CHANGE BIOLOGY
卷 21, 期 1, 页码 388-395出版社
WILEY
DOI: 10.1111/gcb.12643
关键词
climate change; carbon dioxide; temperature; peatland; poor fen; Sphagnum; Carex; water table
资金
- Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant program
- Canada Research Chairs program
- NSERC Strategic Network
- Ontario Ministry of Natural Resources' Far North and Science and Research Branches
The composition of a peatland plant community has considerable effect on a range of ecosystem functions. Peatland plant community structure is predicted to change under future climate change, making the quantification of the direction and magnitude of this change a research priority. We subjected intact, replicated vegetated poor fen peat monoliths to elevated temperatures, increased atmospheric carbon dioxide (CO2), and two water table levels in a factorial design to determine the individual and synergistic effects of climate change factors on the poor fen plant community composition. We identify three indicators of a regime shift occurring in our experimental poor fen system under climate change: nonlinear decline of Sphagnum at temperatures 8 degrees C above ambient conditions, concomitant increases in Carex spp. at temperatures 4 degrees C above ambient conditions suggesting a weakening of Sphagnum feedbacks on peat accumulation, and increased variance of the plant community composition and pore water pH through time. A temperature increase of +4 degrees C appeared to be a threshold for increased vascular plant abundance; however the magnitude of change was species dependent. Elevated temperature combined with elevated CO2 had a synergistic effect on large graminoid species abundance, with a 15 times increase as compared to control conditions. Community analyses suggested that the balance between dominant plant species was tipped from Sphagnum to a graminoid-dominated system by the combination of climate change factors. Our findings indicate that changes in peatland plant community composition are likely under future climate change conditions, with a demonstrated shift toward a dominance of graminoid species in poor fens.
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