Functional traits and acclimation of Central European deciduous forests during the Piacenzian

The Piacenzian (-3.6 to -2.58 Ma) represents one of the last major phases of global warming in recent Earth history, preceding the onset of Pleistocene glacial-interglacial cycles. Under conditions of global mean temperatures 2-3 °C higher than present, atmospheric CO₂ concentrations comparable to modern values, and elevated sea level, Central Europe experienced the expansion of extensive deciduous forests that dominated late Pliocene landscapes. This paper synthesises palaeobotanical and palaeoenvironmental evidence for Central European deciduous forests during the Piacenzian, focusing on environmental context, taxonomic composition, and ecological functioning. The analysis highlights the combined influence of warm climatic conditions, Atlantic oceanic circulation, and relatively stable precipitation regimes on the development of dense temperate forests. Orbital forcing during the late Pliocene nevertheless introduced climatic variability that affected regional biome distribution. Palaeobotanical records indicate a high diversity of Fagaceae dominated by Quercus and Fagus. White oaks acted as major structural elements, while beech shows marked morphological continuity between fossil and extant forms. A trait-based functional approach suggests that forest persistence relied on deciduousness, phenotypic plasticity, and, in oaks, interspecific hybridisation, primarily reflecting acclimation processes rather than major taxonomic reorganisation. The Piacenzian thus provides a valuable reference for assessing functional responses and acclimation limits of temperate forests under sustained warming, while emphasising the need for caution in actualistic interpretations.