To anticipate European climate scenarios for the end of the century, we explored the climate gradient within the REINFFORCE (RÉseau INFrastructure de recherche pour le suivi et l’adaptation des FORêts au Changement climatiquE) arboreta network, established in 38 sites between latitudes 37° and 57°, where 33 tree species are represented. We aim to determine which climatic variables best explain their survival and growth, and identify those species that are more tolerant of climate variation and those of which the growth and survival future climate might constrain. We used empirical models to determine the best climatic predictor variables that explain tree survival and growth. Precipitation-transfer distance was most important for the survival of broadleaved species, whereas growing-season-degree days best explained conifer-tree survival. Growth (annual height increment) was mainly explained by a derived annual dryness index (ADI) for both conifers and broadleaved trees. Species that showed the greatest variation in survival and growth in response to climatic variation included Betula pendula Roth, Pinus elliottii Engelm., and Thuja plicata Donn ex D.Don, and those that were least affected included Quercus shumardii Buckland and Pinus nigra J.F.Arnold. We also demonstrated that provenance differences were significant for Pinus pinea L., Quercus robur L., and Ceratonia siliqua L. Here, we demonstrate the usefulness of infrastructures along a climatic gradient like REINFFORCE to determine major tendencies of tree species responding to climate changes.

Understanding how climate affects tree phenology, biotic and abiotic vulnerability, is a most important research subject. Particularly, climate warming appears to lengthen the growing season, which may affect the exposition to insect pests and pathogens. Also, extreme weather events combined with shifts in phenology may have dramatic consequences, such as early leaf flushing exposure to freezing events. In this study 2 arboreta were followed in the south most distribution of the REINFFORCE Network (Lisbon and Sintra) for 3 species, one native (Quercus robur L.) and 2 non-native (Quercus rubra L. and Betula pendula Roth). Plant growth, leaf phenology and insect damage were assessed according to protocols defined under REINFFORCE project. Species x site interaction was found significant for survival and growth. Phenology differed between and within all species. No difference found for frost tolerance. B. pendula had earlier bud burst at both sites, resulting in a longer growth period, and higher stem growth, being least affected by insect damage, although survival was affected under higher temperature, where Q. robur performed better. This study corroborates the importance of REINFORCE arboreta network as a tool to assess climate change impact on forest species and support assisted migration considering climate change scenarios.

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