title: Importance of vegetation classes in modeling CH4emissions from boreal and subarctic wetlands in Finland.
abstract: Boreal/arctic wetlands are dominated by diverse plant species, which vary in their contribution to CH4production, oxidation and transport processes. Earlier studies have often lumped the processes all together, which may induce large uncertainties into the results. We present a novel model, which includes three vegetation classes and can be used to simulate CH4emissions from boreal and arctic treeless wetlands. The model is based on an earlier biogeophysical model, CH4MODwetland. We grouped the vegetation as graminoids, shrubs and Sphagnum and recalibrated the vegetation parameters according to their different CH4production, oxidation and transport capacities. Then, we used eddy-covariance-based CH4flux observations from a boreal (Siikaneva) and a subarctic fen (Lompolojänkkä) in Finland to validate the model. The results showed that the recalibrated model could generally simulate the seasonal patterns of the Finnish wetlands with different plant communities. The comparison between the simulated and measured daily CH4fluxes resulted in a correlation coefficient (R2) of 0.82 with a slope of 1.0 and an intercept of -0.1mgm-2h-1for the Siikaneva site (n=2249, p<0.001) and an R2of 0.82 with a slope of 1.0 and an intercept of 0.0mgm-2h-1for the Lompolojänkkä site (n=1826, p<0.001). Compared with the original model, the recalibrated model in this study significantly improved the model efficiency (EF), from -5.5 to 0.8 at the Siikaneva site and from -0.4 to 0.8 at the Lompolojänkkä site. The simulated annual CH4emissions ranged from 7 to 24gm-2yr-1, which was consistent with the observations (7-22gm-2yr-1). However, there are some discrepancies between the simulated and observed daily CH4fluxes for the Siikaneva site (RMSE=50.0%) and the Lompolojänkkä site (RMSE=47.9%). Model sensitivity analysis showed that increasing the proportion of the graminoids would significantly increase the CH4emission levels. Our study demonstrated that the parameterization of the different vegetation processes was important in estimating long-term wetland CH4emissions.
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
authors: Tingting
authors: T
authors: Li
authors: Department of Physics, P.O. Box 48, FI-00014, University of Helsinki, Finland.
authors: Maarit
authors: M
authors: Raivonen
authors: Department of Physics, P.O. Box 48, FI-00014, University of Helsinki, Finland.
authors: Pavel
authors: P
authors: Alekseychik
authors: Finnish Meteorological Institute, Atmospheric Composition Research, P.O. Box 503, FI-00101 Helsinki, Finland.
authors: Mika
authors: M
authors: Aurela
authors: Finnish Meteorological Institute, Atmospheric Composition Research, P.O. Box 503, FI-00101 Helsinki, Finland.
authors: Annalea
authors: A
authors: Lohila
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
authors: Xunhua
authors: X
authors: Zheng
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
authors: Qing
authors: Q
authors: Zhang
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
authors: Guocheng
authors: G
authors: Wang
authors: Department of Physics, P.O. Box 48, FI-00014, University of Helsinki, Finland.
authors: Ivan
authors: I
authors: Mammarella
authors: Department of Physical Geography and Ecosystems Science, Lund University, Sölvegatan 12, S-223 62, Lund, Sweden.
authors: Janne
authors: J
authors: Rinne
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
authors: Lijun
authors: L
authors: Yu
authors: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China.
authors: Baohua
authors: B
authors: Xie
authors: Department of Physics, P.O. Box 48, FI-00014, University of Helsinki, Finland; Department of Forest Sciences, P.O. Box 27, FI-00014, University of Helsinki, Finland. Electronic address: timo.vesala@helsinki.fi.
authors: Timo
authors: T
authors: Vesala
authors: LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China. Electronic address: zhw@mail.iap.ac.cn.
authors: Wen
authors: W
authors: Zhang
keywords: Boreal and subarctic wetlands; CH4MOD(wetland); Methane; Parameterization; Vegetation community