1.36 million years of Mediterranean forest refugium dynamics in response to glacial-interglacial cycle strength

Forest conservation and restoration are important means to counter threats caused by habitat fragmentation and global change. Diverse and resilient forests can only be maintained if we understand their sensitivity to past climate change. The sedimentary record of the oldest extant lake in Europe, Lake Ohrid (North Macedonia, Albania), shows the survival and extinction of tree species during glacial and interglacial stages (G-IG) of the Quaternary. Pollen analysis reveals that the area was an effective refuge for tree populations through G-IG periods. The lake body locally buffered the climate, allowing repeated recovery of tree populations that were close to disappearance. However, extended periods of aridity during G-IG intensification after 0.94 Ma caused many tree taxa to disappear.