Climate change threatens the role of European forests as a long-term carbon sink. Assisted migration aims to increase the resilience of forest tree populations to climate change, using species-specific climatic limits and local adaptations through transferring seed provenances. We modelled assisted migration scenarios for seven main European tree species and analysed the effects of species and seed provenance selection, accounting for environmental and genetic variations, on the annual above-ground carbon sink of regrowing juvenile forests. To increase forest resilience, coniferous trees need to be replaced by deciduous species over large parts of their distribution. If local seed provenances are used, this would result in a decrease of the current carbon sink (40 TgC yr⁻¹) by 34–41% by 2061–2080. However, if seed provenances adapted to future climates are used, current sinks could be maintained or even increased to 48–60 TgC yr⁻¹.

Norway spruce (Picea abies (L.) H. Karst.) is predicted to decrease its abundance in the Eastern Baltic region as a result of climatic changes, and this process is already explicit at the southern limit of species lowland distribution. Still, there are uncertainties about the growth potential of Norway spruce within the region due to the plasticity of local populations. In this regard, an assessment of regional weather–growth responses, assuming a nonlinearity of the ecological relationship, can aid in the clarification of uncertainties regarding growth. Nonlinear regional weather–growth relationships for Norway spruce were assessed based on tree-ring widths from 22 stands spreading from Southern Finland to Northern Germany using dendrochronological methods and a generalized additive mixed model. Temporal and spatial stationarity of local linear weather–growth relationships was evaluated. Considering the drought sensitivity of Norway spruce, meteorological variables related to the summer moisture regime were the main predictors of radial increment, though conditions in winter and spring had complementary effects. Generally, the linear weather–growth relationships were spatially and temporary nonstationary, with some exceptions in Poland and Northern Germany. Explicit local specifics in the linear weather–growth relationships, which are common in the marginal parts of species’ distribution, were observed in Estonia, Latvia, and Poland. The estimated regional weather–growth relationships were mostly nonlinear, implying disproportional responses to climatic changes, particularly to intensifying drought conditions across the studied climatic gradient. Still, the responses to winter temperature suggested that warming might contribute to growth. The estimated linear and nonlinear growth responses indicate strict limitation by drought conditions, implying reductions of increment due to climatic changes southward from Latvia, suggesting the necessity for proactive management. Nevertheless, in the northern part of the analyzed region, the projected climatic changes appear favorable for growth of Norway spruce in the near future.

Silvicultural practices can alter forest genetic resources in unpredictable ways, thereby influencing the adaptive and evolutionary potential of forest populations. This is especially alarming in the case of species with more northern distribution centers, due to the lack of area that can be colonized further north. In this article, we studied the genetic diversity of the Scots pine seed tree stand in Poland, its natural regeneration, and two artificially established progeny plantations. The research aimed to determine whether the regeneration mode had affected the efficiency of the gene pool transmission from the maternal seed stand to its offspring. Using nuclear microsatellite markers we compared the parameters of genetic variation and allelic composition among the studied stands. The results showed that all stands represent a common genetic pool with slightly higher values of observed heterozygosity in the case of progeny plantations. Inbreeding was significant only in natural regeneration. All stands have gained and lost rare alleles compared to the maternal seed stand. Nevertheless, the analysis of population differentiation showed that the gene pool of the maternal stand had been transmitted more efficiently to the natural regeneration, though the difference was only minimal. Possible reasons for the differences in transmission efficiency between natural regeneration and artificially established progeny plantations mainly include variations in the number of mother trees and crossing patterns in different reproductive seasons. Furthermore, some individuals that grow in the studied progeny plantations may be natural regeneration of the neighboring stands. In light of the obtained results, we discuss the genetic considerations for establishing and using seeds from progeny plantations in Poland.

The intraspecific variation of climate–growth relationships observed on provenance trials results from among–provenance differences in phenotypic plasticity. Temporal variation in radial growth synchrony among provenances may be modified by adverse climatic/biotic conditions such as drought or insect defoliation. However, these factors can potentially diminish provenance–specific growth reactions and, consequently, prevent the identification of provenances with the highest adaptive potential. Thus, understanding the influence of major biotic conditions on provenance–specific climate–growth relationships seems to be important to anticipate climate change. To determine provenance–specific growth patterns in relation to climate conditions (drought), seed production (reproductive effort), and insect defoliation in a common garden of Scots pine (Pinus sylvestris L.), we applied dendroecological techniques to time–series of tree–ring widths and basal area increments. The long–term records of seed production and insect outbreaks from the local Scots pine stands were used to explain the potential effect of biotic factors on the temporal dynamics of radial growth synchrony. During a period of favorable growth conditions, Scots pine provenances showed a decline in inter–provenance synchronicity in growth patterns, while during years affected by severe soil water deficit and insect defoliation, they manifested high uniformity in growth dynamics. The long–term trend in growth synchrony among P. sylvestris provenances depend on both abiotic and biotic environmental factors. This gains significance following an introduction of the appropriate selection of tree provenances for climate–smart forestry.