The last decades are characterized by an upsurge of research on the impacts of global environmental changes on forests. Climate warming, atmospheric deposition of acidifying and eutrophying pollutants and land-use change are three of the most important threats to biodiversity in temperate forests. However, most studies focused on the effects of single factors over short time periods, such that our ability to predict the combined effects of multiple global change drivers over longer time periods remains rudimentary. The lack of knowledge on effects of global change drivers on forest herb layer communities is particularly striking, since the herb layer contains the largest part of vascular plant diversity in temperate forests and provides key ecosystem services. Therefore PASTFORWARD will build an integrative understanding of the interactive effects of land-use change, atmospheric deposition and climate warming on forest herb layer communities, starting from the insight that changes in herb layer communities are driven primarily by past land use, but can be modulated by atmospheric deposition, climate warming and forest management. Indeed, it is still largely ignored that sensible predictions of herb layer development trajectories under global change can only be made by taking the forest’s land-use history into account, as legacies of past land use can leave century-long imprints on forest herb layer communities. Three complementary data sources (a database with resurveyed vegetation plots, field measurements in a pan-European network of resurvey plots, and a multi-factor experiment) combined with an ecosystem model will be used. Furthermore, concepts and tools from different disciplines, ranging from history over sylviculture to community and ecosystem ecology will be applied. The results of PASTFORWARD will help forest managers and policy makers in taking more informed decisions on how to combine resource extraction with biodiversity conservation.