Because rates of migration and genetic adaptation are slow, trees must initially acclimate to climate change via intra-individual phenotypic plasticity (IPP). Geographical variation in IPP will influence population dynamics through its effects on tree growth and survival and must be considered when predicting distribution and persistence of tree species under future climate change. For example, European beech exhibits high phenological plasticity, which enables populations in the southern range edge to continue reproducing despite increasing temperatures. We investigated geographical variation of IPP of Japanese beech and found that among 13 sites spread across its full distribution range, IPP was lower in the Pacific than Japan-Sea regions, low for isolated southern populations, and high near the northern and altitudinal range edges. Low plasticity may reflect low acclimation potential to environmental perturbation, which could lead to local extinction if climatic conditions exceed the range of tolerance for individual trees. Presentations in this symposium include observational and experimental data on the response of canopy trees to variable environmental conditions. Collectively, these data will allow us to infer acclimation potential of trees and forests to future climate change.