The chapter gives an overview of the research at the Waldstein site related to “fluxes of energy and matter of a forest ecosystem” from the founding of BITÖK (Bayreuth Institute of Terrestrial Ecosystem Research) in 1992 up to the present. This includes tables of all relevant projects and experiments together with the scientific focus of these initiatives and the link to the relevant chapters of the book. The research periods can be separated into two parts: the BITÖK funding up to 2004, with additional funding for carbon fluxes by the European Community, and the single projects, funded mainly by the German Science Foundation, under the umbrella of BayCEER (Bayreuth Center of Ecology and Environmental Research) since 2005. Due to a stable program of climate and air pollution monitoring, it was easy to piggyback comprehensive experimental activities. The FLUXNET station DE-Bay has a nearly 20- year measuring file covering a change from a more homogeneous to a heterogeneous forest.