Climatic Stress Test of Scots Pine Provenances in Northeastern Europe Reveals High Phenotypic Plasticity and Quasi-Linear Response to Warming

Research Highlights: Scots pine (Pinus sylvestris L.) phenotypic plasticity will buffer and even benefit from temperature increases in Northeast Europe this century, except for the southern peripheries of the range. Objectives: The "stress test" aimed to assess the inherent potential of existing populations to withstand projected changes in their lifetimes at their original location. Materials and Methods: This study applied an alternative analytic approach to calculate response and transfer equations from historic height growth data from provenance tests in the former USSR and Hungary. Results: Contrary to earlier analyses, the populations displayed quasi-linear responses to mimicked warming without clear ecological optima, forecasting a general growth acceleration north of Lat. 53 degrees N. Climate-triggered mortality is predicted for the near future in the southern peripheries. Locally adapted populations at the distribution confines of the northern and southern limits deserve special attention. Conclusions: The observed adaptability to warming moderates the necessity of genetic management interventions such as assisted migration. The support of natural processes of adaptation and acclimation will be sufficient in boreal and central Northeast Europe this century. Evacuating heat and drought-tolerant populations should be envisaged in the endangered zone to conserve valuable genetic resources.