In temperate forests, the understorey harbors the majority of plant biodiversity. Conserving and restoring this understorey diversity is crucial to maintain ecosystem services provided by forests. In this project, I will study the interactive effects of two key global-change drivers on understorey communities: drought and fragmentation. In the past decades, we have witnessed an unprecedented high frequency of extreme drought events. Forest canopies can buffer such climate extremes and promote microclimates that protect understorey species. However, forest fragmentation increases the proportion of edge area, which in turn decreases the microclimatic buffering potential. As such, I expect that fragmentation may exacerbate the impact of drought stress on understorey communities. First, I will test this through resurveying forest patches after a decade of drought (2012-2023), along a gradient in patch size and a latitudinal macroclimate gradient. Then, I will investigate how plants differ in their drought-related functional traits under different microclimatic conditions along the edge-to-core gradients across Europe. Finally, I will further our mechanistic understanding of these findings through an in situ multifactorial experiment, applying warming and drought treatments on understorey communities. Ultimately, this project will build a scientific basis to promote and conserve understorey diversity in fragmented landscapes under projected future increases in drought frequency.