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Scots pine is a crucial component of ecosystems in Europe and Asia and a major utility species that comprises more than 60% of total forest production in Poland. Despite its importance, the genetic relationships between key conservation and the commercial value of Scots pine ecotypes in Poland remain unclear. To address this problem, we analyzed 27 populations (841 trees) of the most valuable Polish Scots pine ecotypes, including the oldest natural stands in all 24 regions of provenance established for the species in the country. By examining maternally inherited mitochondrial markers, nuclear microsatellite loci, and thousands of SNP markers from a genotyping array, we evaluated the genetic structure between and within them. These multilevel genomic data revealed high genetic similarity and a homogeneous structure in most populations, suggesting a common historical origin and admixture of populations after the postglacial recolonization of Central Europe. This research presents novel data on existing genomic resources among local ecotypes defined within strictly managed Polish regions of provenance, challenging their validity. Formal tests of the progeny of seed stands are needed to check whether the diversity in adaptation and quantitative traits still supports the delineation of provenance regions. In parallel, the health status of selected populations and the viability of seeds from these regions should be monitored to detect early‐stage symptoms of their environmental stress. It seems reasonable that periodic shortages of forest reproductive material (FRM) in a given region of provenance could be supplemented with the one from other regions that match their climatic envelope. Together, our results have important implications for the management of native Scots pine stands, particularly elite breeding populations, as they contribute to the discussion of the boundaries of provenance regions and the transfers of FRM that face increasing climate change. [ABSTRACT FROM AUTHOR]

Tree crown shape is an important trait affecting the light environment in forest canopies. We examined genetic and environmental effects on outer crown shape of young single-family stands of loblolly pine (Pinus taeda L.). Crown diameter profiles were measured after canopy closure at four experimental sites in the southeastern US. The two examined families of contrasting aboveground productivity differed in crown length but not in their outer crown shapes or crown shape ratios, defined as the ratio of crown diameter to crown length. Within each site, intensive silvicultural treatment, consisting of fertilization and control of competing vegetation, had little effect upon crown shape. A strongly significant effect of site on crown shape parameters was found in the family grown at all four experimental sites; however, density differences among the experimental series likely accounted for a part of the across-sites variation in crown shape. In contrast to other studies on crown shape in trees, and to findings at age 2 years in the same stands, we conclude that family effects on the outer crown shape were small compared with the environmental effects in these 5-year-old pine plantations, following canopy closure. La forme de la cime des arbres est un trait important qui influence l'environnement lumineux dans la canopee des forets. Nous avons etudie les effets d'ordre genetique et environnemental sur la forme de la partie externe de la cime dans de jeunes peuplements composes de pin a encens appartenant a une meme famille. Des profils du diametre de la cime ont ete mesures apres la fermeture du convert dans quatre stations experimentales situees dans le sud-est des Etats-Unis. Deux familles dont la productivite aerienne etait differente ont ete etudiees. Elles se distinguaient par la longueur de la cime mais non par la forme de la partie externe de la cime, c'est-a-dire le rapport du diametre de la cime sur sa longueur. Dans chaque station, des traitements sylvicoles intensifs, incluant la fertilisation et la maetrise de la vegetation, ont eu pen d'effet sur la forme de la cime. Un effet tres signifcanf de la station sur les parameters de la forme de la cime a ete note dans le cas de la famille etablie dans les quatre stations experimentales. Cependant, des differences de densite entre les series experimentales expliquaient probablement une partie de la variation dans la forme de la cime d'une station a l'autre. Contrairement aux resultats d'autres etudes sur la forme de la cime des arbres et a ceux qui ont ete obtenus dans les memes peuplements lorsqu'ils etaient ages de deux ans, une fois le couvert ferme dans ces plantations maintenant agees de cinq ans, nous concluons que la forme de la partie externe de la cime est influencee par des facteurs d'ordre environnemental beaucoup plus que genetique. [Traduit par la Redaction], Introduction Crown shape, together with total leaf area and its distribution within the crown, affects light interception and photosynthesis in a forest canopy. Since stand growth is related to canopy [...]

Increasing growth and biomass accumulation in forest stands may positively contribute to carbon (C) sequestration and climate change mitigation. Tree improvement programs develop planting material with enhanced growth and biomass accumulation. Scots pine is commonly planted in Europe, and provides a potential for increased C accumulation in forest biomass when using improved seed origins. Our objective was to investigate variation in standing aboveground C accumulation among the progeny of Scots pine seed orchards in climatically variable environments, where we also compared the amount of accumulated C between the tested populations and commercial stands. The aboveground biomass of trees in two series of replicated common garden trials was estimated with eight allometric equations, converted into C, and expressed per unit area. For each trial site we selected reference stands matching the age, stand composition and forest site type, where the same measurements and calculations were done on sample plots. We specifically expected to find the progeny that would express better growth and greater accumulation of C in their biomass when compared to the reference stands. Significant and large variation was found among the examined seed sources and trial sites. On average, aboveground C accumulation varied among sites from 31.0 to 60.4 Mg ha-1 (age 22) and from 25.5 to 34.0 Mg ha-1 (age 17). Differences between populations at individual sites ranged from 41% to 55% (age 22), and from 29% to 54% (age 17). However, only a few of the investigated progeny had C accumulation significantly greater than the reference stands, and some had a lower C accumulation, depending on the study site. This study for the first time quantifies the amount of and variation in aboveground C accumulation among the progeny of Scots pine clonal and seedling seed orchards in Poland. It also contributes to the knowledge of the patterns of within-species variation in growth and biomass accumulation. Variation we found is promising for the potential to enhance C sequestration in forest stands through tree improvement. However, the lower C accumulation or non-significant differences between research trials and reference stands, indicate that the level of growth enhancement from phenotypic selection practiced so far in Polish forestry is limited. For increased C sequestration in planted forests, selection would need to be intensified. [ABSTRACT FROM AUTHOR]

The dormancy and the growth of trees in temperate climates are synchronized with seasons. Preparation for dormancy and its proper progression are key for survival and development in the next season. Using a unique approach that combined microscopy and proteomic methods, we investigated changes in Norway spruce (Picea abies (L.) H. Karst.) embryonic shoots during four distinct stages of dormancy in natural weather conditions. We identified 13 proteins that varied among dormancy stages, and were linked to regulation of protein level; functioning of chloroplasts and other plastids; DNA and RNA regulation; and oxidative stress. We also found a group of five proteins, related to cold hardiness, that did not differ in expression among stages of dormancy, but had the highest abundancy level. Ultrastructure of organelles is tightly linked to their metabolic activity, and hence may indicate dormancy status. The observed ultrastructure during endodormancy was stable, whereas during ecodormancy, the structural changes were dynamic and related mainly to nucleus, plastids and mitochondria. At the ultrastructural level, the lack of starch and the presence of callose in plasmodesmata in all regions of embryonic shoot were indicators of full endodormancy. At the initiation of ecodormancy, we noted an increase in metabolic activity of organelles, tissue-specific starch hyperaccumulation and degradation. However, in proteomic analysis, we did not find variation in expression of proteins related to starch degradation or to symplastic isolation of cells. The combination of ultrastructural and proteomic methods gave a more complete picture of vegetative bud dormancy than either of them applied separately. We found some changes at the structural level, but not their analogues in the proteome. Our study suggests a very important role of plastids' organization and metabolism, and their protection in the course of dormancy and during the shift from endo- to ecodormancy and the acquisition of growth competence. [ABSTRACT FROM AUTHOR]

Forest biomass studies not only range from estimation of timber standing mass to assessing biogeochemical cycles, but may also reveal genetic variation in growth and biomass allocation. In this study, we investigated differences in biomass accumulation and allometric relationships between tree diameter and biomass of above and belowground components in two populations of Scots pine (Pinus sylvestrisL.) (progeny of clonal seed orchards) differing in stem growth. At a common tree diameter, populations differed in accumulated belowground biomass, but not in total tree or aboveground components' biomass. Populations also differed in the root:shoot ratio and proportional allocation of biomass into stems. However, proportional allocation to stem mass decreased from smaller to larger trees, contrary to branch and foliage, which likely reflected a response to competition in the stand. The allometric equations predicted well the total tree, aboveground, and stem biomass independently of population, but separate equations were required for estimation of belowground biomass for the two populations. These results suggest that total stand and aboveground biomass in young Scots pine stands could be estimated without accounting for genetic component. Comparison of literature data with estimates obtained using our allometric equations indicate that equations were site-specific and should not be generalized to other sites, unless for rough approximation of aboveground biomass. More research is required for a more reliable assessment of genetic effect on allometric relationships for belowground biomass. [ABSTRACT FROM AUTHOR]

Crown architecture and size influence leaf area distribution within tree crowns and have large effects on the light environment in forest canopies. The use of selected genotypes in combination with silvicultural treatments that optimize site conditions in forest plantations provide both a challenge and an opportunity to study the biological and environmental determinants of forest growth. We investigated tree growth, crown development and leaf traits of two elite families of loblolly pine (Pinus taeda L.) and one family of slash pine (P. elliottii Mill.) at canopy closure. Two contrasting silvicultural treatments--repeated fertilization and control of competing vegetation (MI treatment), and a single fertilization and control of competing vegetation treatment (C treatment)--were applied at two experimental sites in the West Gulf Coastal Plain in Texas and Louisiana. At a common tree size (diameter at breast height), loblolly pine trees had longer and wider crowns, and at the plot-level, intercepted a greater fraction of photosynthetic photon flux than slash pine trees. Leaf-level, light-saturated assimilation rates (Amax) and both mass- and area-based leaf nitrogen (N) decreased, and specific leaf area (SLA) increased with increasing canopy depth. Leaf-trait gradients were steeper in crowns of loblolly pine trees than of slash pine trees for SLA and leaf N, but not for Amax. There were no species differences in Amax, except in mass-based photosynthesis in upper crowns, but the effect of silvicultural treatment on Amax differed between sites. Across all crown positions, Amax was correlated with leaf N, but the relationship differed between sites and treatments. Observed patterns of variation in leaf properties within crowns reflected acclimation to developing light gradients in stands with closing canopies. Tree growth was not directly related to Amax, but there was a strong correlation between tree growth and plot-level light interception in both species. Growth efficiency was unaffected by silvicultural treatment. Thus, when coupled with leaf area and light interception at the crown and canopy levels, Amax provides insight into family and silvicultural effects on tree growth. [ABSTRACT FROM AUTHOR]