Disparate response to water limitation for vessel area and secondary growth along Fagus sylvatica southwestern distribution range

The response of European beech (Fagus sylvatica L.) to climate warming will depend on the ability their populations adjust tree performance water shortage. By exploring inter- and intra-annual variations in secondary growth mean vessel area (MVA), we assessed effects precipitation cambial activity hydraulic control during expansion phase along lifes. We sampled at low high altitude from four mountain ranges across its southwestern distribution edge. measured a total 45,897 rings 126 trees 5.5 million vessels 76 trees. built chronologies for ring width MVA between 1950 2017, calculated responses evaluated region, chronology type (ring-width vs. MVA) by means ordinations (PCA) constrained (pRDA). Precipitation controlled beech's range, but different time domains. Ring responded primarily summer previous growing season, whereas availability phase, with timing shifting ring, according moment expansion. Regional differences were significant, low, compared effect type. A large part variance explained region was due strong difference Western Pyrenees forests –growing under hyperhumid conditions– rest drier warmer climate. Only minor altitudes found size annual scale, no MVA. stronger climatic role geographical location or suggests common constraints xylem anatomy dry