Global Change and Land Use Effects on Carbon Turnover in Tidal Wetlands Tidal wetlands such as tidal marshes and mangroves are global hotspots for carbon sequestration. The preservation of organic matter is a critical process by which tidal wetlands exert their strong influence over the global carbon cycle and at the same time gain elevation to keep pace with sea level rise. This thesis addresses the effects of numerous global change factors (sea level rise warming land use change biological invasions) on organic matter turnover processes in tidal wetlands aiming to assess their role in the carbon sequestration potential of these ecosystems. Besides studying direct effects of different factors on decomposition and turnover processes this work is particularly focused on plant mediated and thus indirect effects. The thesis is structured in 7 chapters including a general introduction to the topic (Chapter 1) five manuscripts as the main part (Chapters 2 6) and a synthesis discussing the links between the single chapters their implications and resulting future research perspectives (Chapter 7).