In the near future, it is predicted that the natural distribution range of forest tree species will be reshaped due to the rapid changes in climate conditions. The assisted migration of species in favorable environmental conditions, as future solutions for sustainable forest management, could be supported by genetic tests. This study aims to evaluate the adaptive potential of European beech (Fagus sylvatica L.) and the opportunities for applying assisted migration practices in the Carpathian region of Romania. Growth and stability performances, as well as phenotypic plasticity of 31 international beech provenances, were assessed in two common garden experiments located in optimum growing conditions and at the eastern margin of the beech distribution range, respectively. For all analyses, trees height, breast height diameter, and survival were determined. Survival and growth traits were higher by 6–8% in the ecological optimum for beech. The highest mean plasticity was obtained by three provenances from France and one from Denmark. Three provenances performed better in both trials. Increasing the management sustainability of beech forests in a changing climate might be possible by using assisted migration practices, which include the promotion of the highest adapted and productive provenances only in the provenance region where they performed.

Swiss stone pine (Pinus cembra L.) may represent a vital species for afforestation at the upper altitudinal limits of forests due to its adaptability to challenging environmental conditions. In this study, we aimed to analyze the variability in ring width (radial growth, RW, earlywood, EW, latewood, LW, and latewood proportion, LWP) and the influence of different sites on the climatic resilience of twelve European provenances of Swiss stone pine to identify the best-adapted provenances. Five provenances from the Alps and seven from the Carpathians were tested across two 27-year-old field trials conducted in the Eastern and Southern Carpathians. Moderate genetic differentiation among the provenances was noted, which could ensure the success of breeding programs. Based on ring width and latewood proportion, we successfully selected the 25% best-performing provenances and recommend them for use in the provenance regions where have performed. The significant influence of the testing site and the different outcomes of the provenances necessitate extreme attention during the transfer of forest reproductive materials. Additionally, the breeding strategies applied in the two trials differed, consisting in individual selection in the Cugir trial and provenance selection in the Cârlibaba trial. The low resistance of all provenances shown in both trials, particularly in the Cugir trial, is worrying in the context of global warming.

Swiss stone pine (Pinus cembra) is a viable solution for afforestation in the high mountain zone, at the upper limit of the forests, due to the species adaptation ability to the limiting climatic conditions. The aim of this study was to analyse the genetic variability, inheritance rate and juvenile-adult correlations, in a 26 years full-sib (10x10 complete mating design) trial, in order to predict the genetic gain of forward selection. In the spring of 2023, measurements and evaluations were carried out for all the existing trees, for Survival rate (Sr), growth (Diameter as breast height- Dbh, Trees' height- Th, Trees' volume- Tv) and quality traits (Forks, stem slenderness- Ss, branches' diameter- Bd, branches' finesse- Bf, defoliation- Def). The 90 cross-pollinated (CP) families registered 50% of Sr whereas the other 10 selfcross-pollinated (consanguineous) registered just 11% of Sr, and the majority of those trees are dominated and face extinction in the next years. Juvenile-adult correlations were highly significant (p<0.001), indicating that early selection (at the age of 14 years) might be efficient. At the trial age, based on the medium to high heritabilities, the forward selection of the best 10% individual trees from the top 20 of the 90 CP families, for Dbh, could be applied, which ensure at least 9.2% of genetic gain.

The research objective was to demonstrate the economic impact of using, in afforestation, forest reproductive materials (FRMs) obtained from seed trees selected in the most valuable Norway spruce populations of the FGRs’ (forest genetic resources’) category. The values obtained for the main growth traits (diameter at breast height (Dbh), tree height (Th), and tree volume (Tv)), both in the FGR and in the closest population (with the same age and growth in similar environmental conditions), were compared. Three comparative trials were analyzed, each belonging to different breeding levels: Open-pollinated (Breţcu, 40 years old), half-sib (Măneciu, 25 years), and full-sib (Comandău, 23 years). The difference in volume/hectare between the FGR and an unimproved neighbor population was economically quantified (€), based on the average price per cubic meter (m³) of spruce wood in Romania; the profit at the end of the rotation period (110 years) was projected taking into account the genetic gain that will result from the use of FRM collected from the FGRs. The average FGR growth results were superior to the unimproved neighbor populations, with 8%–13%, 14%–25%, and 26%–79% for Dbh, Th, and volume/ha, respectively, and the differences increased if the best 10% seed trees of the trials were used. For Th, a five times higher family mean heritability was registered for the pendula trees (compared to pyramidalis) in the half-sib trial, while in the full-sib experiment, the pendula trees (both full and half pendula) again registered higher heritability, but for Dbh, which recommends the pendula selection for different traits in the two trials. These results have led to a rate of profitability between 540 and 3366 €/ha, a value that is predicted to increase until the end of the rotation period, when the genetic gain could generate a profit of 7560 €/ha.

This study analysed the stability of the narrow-crowned Norway spruce (pendula form) compared with the classic form of spruce (pyramidalis form) in two half-sib field trials located in the Romanian Carpathians. From eight natural populations, representative of three of the four large spruce spread areas in Romania, open-pollinated seeds from 48 trees (24 pendula ideotype and 24 pyramidalis form) were collected to install the Maneciu and Soveja trials. In these trials, at age 25 years, measurements were performed for the following traits: tree height, breast height diameter, crown diameter, number of branches per whorl and dominant branch diameter. Some important traits were calculated: average volume per tree, trees’ slenderness, crown slenderness and branches’ finesse. Pearson’s simple correlations between the analysed traits were calculated and also the correlations between traits and geographic and climatic gradients of provenances’ origin. In addition, cores were collected to compare the wood density of the two forms of spruce. In both trials, but especially in the limitative environmental conditions of the Soveja trial, the narrow crowned form of Norway spruce (Picea abies f. pendula) presented more favourable average results than the normal crown spruce form for the most important stand stability traits: trees’ slenderness, wood density, branches’ diameter and branches’ finesse. Between spruce crown forms, in both trials, no significant differences were observed for the growth traits, but between trials, higher results resulted in optimal environmental conditions of the Măneciu test (+89% for the trees’ volume). The trees from different provenances and with specific forms of the crown reacted differently to the changing of the testing site, which required the adoption of maximum caution for decisions regarding the transfer of forest reproductive materials. The correlations between the analysed traits converge towards the adoption of a two-step breeding strategy, starting by selection of narrow crowned trees after stability traits.

In a changing climate, forest managers need to select productive and climate-change-resilient tree species and provenances. Therefore, assessing the growth response of provenances growing in field trials to climate provides useful information for identifying the more appropriate provenance or variety. To determine the genetic gain through selection of the most productive and resilient families and to decipher the role of crown forms of Norway spruces (Picea abies (L.) Karst.), we used 24 families with a classical crown (pyramidalis) and 24 with a narrow crown (pendula) from eight provenances, growing in a 25-year-old comparative trial. The annual wood characteristics (ring width and early- and latewood), the wood resistance (expressed by latewood proportion (LWP)), and the growth response to climate of the two spruce crown forms were investigated. No significant differences between the two spruce forms were found regarding the ring width characteristics. However, three pendula families of Stâna de Vale I provenance exhibited the highest LWP and could be included in a future selection strategy, the respective trait having also high heritability. Radial growth was positively and significantly correlated with previous September and current July precipitation and negatively with current June temperature. Both spruce forms showed good recovery capacity after a drought event.