Effects of temperature and drought manipulations on seedlings of S cots pine provenances

Rising temperatures and more frequent and severe climatic extremes as a consequence of climate change are expected to affect growth and distribution of tree species that are adapted to current local conditions. Species distribution models predict a considerable loss of habitats for P inus sylvestris . These models do not consider possible intraspecific differences in response to drought and warming that could buffer those impacts. We tested 10 E uropean provenances of P . sylvestris , from the southwestern to the central E uropean part of the species distribution, for their response to warming and to drought using a factorial design. In this common‐garden experiment the air surrounding plants was heated directly to prevent excessive soil heating, and drought manipulation, using a rain‐out shelter, permitted almost natural radiation, including high light stress. Plant responses were assessed as changes in phenology, growth increment and biomass allocation. Seedlings of P . sylvestris revealed a plastic response to drought by increased taproot length and root–shoot ratios. Strongest phenotypic plasticity of root growth was found for southwestern provenances, indicating a specific drought adaptation at the cost of overall low growth of aboveground structures even under non‐drought conditions. Warming had a minor effect on growth but advanced phenological development and had a contrasting effect on bud biomass and diameter increment, depending on water availability. The intraspecific variation of P . sylvestris provenances could buffer climate change impacts, although additional factors such as the adaptation to other climatic extremes have to be considered before assisted migration could become a management option.