Methane exchange of a boreal peatland Integrated measurements and modelling on microform and ecosystem scale at the Salmisuo mire complex Eastern Finland Spurengas Meteorologische Messung Ökosystem Modell Landschaftsökologie Treibhausgasemission Skalierung Eddy Kovarianz LPJ trace gas emission scaling eddy covariance Peatlands cover only about 3% of the terrestrial surface but are significant players in the global carbon (C) cycle and the climate system since they store roughly one quarter of the global soil carbon (C) and are among the largest natural sources of methane (CH4). Since the resulting feedbacks on the climate system are uncertain research efforts aim at identifying key processes and quantifying the C exchange from ecosystem to regional and global scales. To identify peatland ecosystem dynamics requires analysis of yet different scales. The key scale for their C dynamics is the microform scale which is the smallest entity of the system. To estimate ecosystem dynamics up scaling from the microform scale is needed. Up scaling demands (1) a correct estimation of the spatial heterogeneity and (2) the correct aggregation. In this thesis the traditional spatial weighting of microform fluxes by the microform distribution is evaluated by (1) analyzing the flux calculation procedure (2) investigating the effect of the resolution of the landcover maps on the up scaling and by (3) cross evaluating the up scaling result with the directly measured ecosystem flux. Eventually it is evaluated how these dynamics are considered in a mechanistic ecosystem model (LPJ WHyMe). CH4 fluxes were measured on the microform scale with the closed chamber technique and on the ecosystem scale with the eddy covariance (EC) technique ...