Climate change drives a shift in peatland ecosystem plant community: Implications for ecosystem function and stability

• Published in: Global change biology Vol. 21; no. 1; pp. 388 - 395
• Main Authors: Dieleman, Catherine M, Branfireun, Brian A, McLaughlin, James W, Lindo, Zoë
• Format: Journal Article
• Language: English
• Published: England Blackwell Science 01.01.2015; Blackwell Publishing Ltd
• Subjects: Analysis of Variance; Biodiversity; botanical composition; Carbon dioxide; Carbon Dioxide - metabolism; Carex; Climate Change; Climate effects; Climatic conditions; Community composition; Community structure; Ecological function; Ecosystem; Ecosystems; Fens; graminoids; Groundwater; High temperature; Hydrogen-Ion Concentration; Models, Biological; Peat; peatland; Peatlands; Plant communities; Plant species; poor fen; Pore water; Species Specificity; Sphagnopsida - physiology; Sphagnum; synergism; Synergistic effect; Temperature; variance; Water table; carbon dioxide; poor fen; peatland; temperature; water table; Carex; Sphagnum; climate change
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/gcb.12643

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 °C above ambient conditions, concomitant increases in Carex spp. at temperatures 4 °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 °C appeared to be a threshold for increased vascular plant abundance; however the magnitude of change was species dependent. Elevated temperature combined with elevated CO₂had 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.