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Warming impacts on boreal fen CO 2 exchange under wet and dry conditions
Author(s) -
Laine Anna M.,
Mäkiranta Päivi,
Laiho Raija,
Mehtätalo Lauri,
Penttilä Timo,
Korrensalo Aino,
Minkkinen Kari,
Fritze Hannu,
Tuittila EevaStiina
Publication year - 2019
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14617
Subject(s) - peat , boreal , environmental science , ecosystem respiration , bog , ecosystem , global warming , climate change , ecology , carbon sink , atmospheric sciences , eddy covariance , biology , geology
Northern peatlands form a major soil carbon (C) stock. With climate change, peatland C mineralization is expected to increase, which in turn would accelerate climate change. A particularity of peatlands is the importance of soil aeration, which regulates peatland functioning and likely modulates the responses to warming climate. Our aim is to assess the impacts of warming on a southern boreal and a sub‐arctic sedge fen carbon dioxide (CO 2 ) exchange under two plausible water table regimes: wet and moderately dry. We focused this study on minerotrophic treeless sedge fens, as they are common peatland types at boreal and (sub)arctic areas, which are expected to face the highest rates of climate warming. In addition, fens are expected to respond to environmental changes faster than the nutrient poor bogs. Our study confirmed that CO 2 exchange is more strongly affected by drying than warming. Experimental water level draw‐down (WLD) significantly increased gross photosynthesis and ecosystem respiration. Warming alone had insignificant impacts on the CO 2 exchange components, but when combined with WLD it further increased ecosystem respiration. In the southern fen, CO 2 uptake decreased due to WLD, which was amplified by warming, while at northern fen it remained stable. As a conclusion, our results suggest that a very small difference in the WLD may be decisive, whether the C sink of a fen decreases, or whether the system is able to adapt within its regime and maintain its functions. Moreover, the water table has a role in determining how much the increased temperature impacts the CO 2 exchange.