Of all terrestrial ecosystems, peatlands store carbon most effectively. However, many peatlands have been drained for peat extraction or agricultural use. This converts peatlands from sinks to sources of carbon, causing approx. 5% of the anthropogenic greenhouse effect and additional negative effects on other ecosystem services. Rewetting peatlands can mitigate the climate crisis and may be combined with management in the form of paludiculture. Rewetted peatlands, however, do not equal their pristine ancestors and their ecological functioning is not understood. This holds especially for fens. Their functioning results from complex interactions and can only be understood following an integrative approach of many relevant fields of science, which we develop in the interdisciplinary project WETSCAPES. Here, we introduce our approach in which we are addressing interactions among water transport and chemistry, primary production, peat formation, matter transformation and transport, microorganisms and greenhouse gas exchange using state of the art methods in the relevant research fields. We record data on six study sites spreading across three important fen types (Alder forest, percolation fen, and coastal fen) each in drained and rewetted state. Using exemplary results, we show the importance of developing an integrative understanding of managed fen peatlands and their ecosystem functioning.