The work detailed here in the context of the above project sought to determine changes in the gene pool (at the DNA level) in a stand of Scots pine (Pinus sylvestris L.), under the influence of various kinds of forest-tending cuts. The experimental area on which the research was focused is located in Poland’s Ostrów Mazowiecka Forest District. Genetic structure was specified using five nuclear SSR sequences and six chloroplast SSR loci, while the five thinning variants trialled were sanitation cutting, low thinning of 30% intensity, schematic thinning, selective thinning and destructive lumbering. The control variant was left untreated. It was virtual rather than real-life thinning that was pursued, using the ForestSimulator BWINPro program. Changes in the structure of the stand after a further 10 years were also simulated. The different thinning variants were shown to cause change in the gene pool and level of genetic diversity of trees in the study area. In terms of maintaining genetic variability in the stand, the least-favourable method proved to be thinning from below. Destructive selection cutting was in turn most beneficial in terms of the preservation of genetic structure, with the reduction in rare alleles being more limited than in any other analysed variant. It was with the selective thinning variant that the final number of trees, stand structure and level of genetic variation resembled the situation in the control most closely. This suggests that selective thinning provides for a rather accurate replication of processes occurring in nature.

The analysis of population variability usually concerns the adaptability of trees to changing climatic conditions and their timber production possibilities. It is already known that several phenotypic and genotypic features determine the adaptation possibilities of a population and every population of a given species may have different adaptability to climatic conditions. The assimilation apparatus is an important phenotypic feature that has a large impact on the functioning of tree organisms and their adaptability. Scots pine, which covers vast areas of Europe, is a very important species in the context of ecosystems’ sustainability preservation, especially in the era of global warming. Therefore, in our research, the inter-population and individual variability of morpho-anatomical features of shoots and needles were analyzed. Nine national origins of Scots pine (three populations each from northern, western, and central Poland), which are a part of a 50-year provenance experiment, were compared. Fragments of one-year-old shoots (5 cm long) with needles were collected from the top parts of tree crowns. An extensive analysis of the morphological parameters of the needles (length and width, density, dry mass) and the anatomical features of the shoots (thickness, the share of bark, wood, and pith) was performed. Our surveys showed that the differences between populations are much greater than between regions. The western pine populations, which have shown the highest volume of wood per ha, had the thickest shoots but the lowest dry mass. The northern populations, highly valued for the very good technical quality of wood, had thin shoots. Pine trees from central Poland had the highest density and dry mass of needles and the highest share of wood in shoots.

Climate changes, taking place in Poland, have a very negative impact on populations of many tree species. An example of a highly endangered and, at the same time, very valuable stock is the population of Norway spruce from the Białowieża Primeval Forest. One of the protection methods of a perishing population is to preserve its genetic pool in the form of seed orchards (ex situ method). The genetic material of spruce mother trees from the Białowieża Primeval Forest has been preserved in a seed orchard with an area of 9.74 ha, established in 1996 in the Bielsk Forest District (approximately 35 km west of the Białowieża Primeval Forest). In December 2017, cones from all growing grafted trees were collected on a sample plot of 50 clones. An extensive analysis of the health of cones, seed yield from cones, and the parameters of cones and seeds was carried out, and the relationship between seed quality and position in the cone was determined. The number of cones on the analyzed trees ranged from 29 to 1766, with the average equal to 405 cones per clone. The greatest threat limiting seed production were insects that damaged seeds in cones. No dieback of grafted trees, due to the activity of the European spruce bark beetle, was detected. The share of undamaged and lightly damaged cones amounted to about 88%. However, the average share of undamaged seeds was less than 50%. Our surveys showed that the approximately 25-year-old plantation is able to give satisfying economic result and assure the preservation of the genetic pool of Norway spruce from the population of the Białowieża Forest.

One adaptive silvicultural strategy to address the increasing frequency and severity of climate extremes is the promotion of genetic material best suited to a changing environment. Using a long-term provenance trial established in 1966 in central Poland, we evaluated how climate humidity at the parental site (provenance origin) influences individual-tree growth–drought resilience trade-offs in Scots pine (Pinus sylvestris L.). Stem discs from 240 trees representing 16 provenances were initially assessed, of which 202 trees were retained following cross-dating and quality control. Drought responses were quantified using complementary growth resilience indices for major drought events identified using the Standardized Precipitation–Evapotranspiration Index. Mixed-effects models followed by Type III Wald chi-square tests and Sidák-adjusted pairwise comparisons revealed significant provenance-level differences in drought responses. Structural equation modeling showed that parental-site climate directly and indirectly affected drought resistance through its influence on relative tree size. Trees from provenances originating in more water-rich environments tended to be smaller but exhibited higher resistance, indicating a potential trade-off between growth and drought tolerance. Relative tree size was also negatively associated with resilience, whereas recovery and relative resilience were not significantly associated with provenance climate or relative tree size. These findings indicate that provenance climate is associated with drought resistance in Scots pine, with tree size emerging as an important mediator of this relationship.

Scots pine (Pinus sylvestris L.) exhibits substantial variation among provenances in growth and wood properties. This study investigated provenance-related variation after nearly six decades of growth under common-garden conditions and examined relationships between tree growth, wood properties and climatic characteristics of provenance origins. The study was conducted in a provenance experiment established in 1966 at the Rogów Forest Experimental Station in central Poland, comprising 16 provenances and five experimental replicates. Tree height, crown length, trunk volume, diameter at breast height (DBH), wood density, dynamic and static modulus of elasticity (MOE_dyn and MOE_st), modulus of rupture (MOR) and compressive strength (CS) were analysed. Provenance significantly affected all traits except MOE_dyn, whereas experimental replicate significantly affected most traits. Correlations calculated across individual trees were generally weak, while provenance-specific relationships varied substantially in strength and direction. At the provenance level, tree height and DBH showed the strongest associations with climatic characteristics of the provenance origins, particularly altitude, mean annual temperature, precipitation, aridity and growing season length. Selected mechanical properties also showed moderate climatic associations. The results demonstrate persistent provenance-related differentiation under common environmental conditions and indicate that growth performance alone cannot reliably predict wood quality. However, the climatic associations should be considered exploratory and do not constitute direct evidence of local adaptation.