Wood Density Traits Research Articles

Usability of fractometer for the purpose of a practical preliminary assessment tool for wood density of Pinus brutia

The fractometer is a device that breaks increment cores to measure fracture strength. The advantages of the device are that it is relatively fast, easy to use in the field, and it can perform direct strength measurements on increment cores. The main purpose of the study was to evaluate the usability of the fractometer as a preliminary evaluation tool for wood density traits of standing Turkish Pinus brutia (red pine) trees. Fracture strength was measured on 5 mm diameter increment cores, and X-ray densitometry was used for density measurements. Due to the high correlation between the two traits (fracture and density), a model was built using linear regression. Fifty trees were sampled to build the statistical model (r2: 0,74), and an equal sample size was used to test the model. The density value obtained from the model was 0,546 gcm-3, while the density value averaged by the X-ray method for the same group was 0,543 gcm-3. When considering mean values, it can be said that the model provides a good prediction. Based on personal experience and research results, some trees exhibited better growth and wood quality traits than others. Breeding from these trees could offer improvement in timber production and performance for Pinus brutia (red pine). As a general consequence, the fractometer and increment core sampling can be used for pine tree breeding programs for the preliminary assessment of wood density.

Genetic parameters and correlations in growth and wood density traits of Balfourodendron riedelianum based on provenance and progeny testing

Abstract Balfourodendron riedelianum is an important timber species of South America used in civil construction and carpentry. Knowing the genetic variation, heritability and correlation between traits is an essential prerequisite for guiding selection of the best genotypes in tree improvement. In this study, growth (diameter and height) and wood density (mean, pith, middle and bark position) traits were investigated in 30-year-old trees planted in a B. riedelianum provenance and progeny test established in two sites, Luiz Antônio (LA) and Pederneiras (PE), in São Paulo State (Brazil). ANOVA results showed significant differences between sites for all traits, among provenances and families for wood density traits in the LA site and among families for growth traits in PE. Provenance x site and family x site interactions were significant for almost traits, and genetic correlation between sites was low for all traits (0.17–0.20). Genetic variation (CV g) was higher (4.0–5.4 %) and mean family heritability (h m 2) was lower for growth (0.12–0.20) compared to wood density (CV g: 2.3–3.8%, h m 2: 0.31–0.59) traits. Genetic correlation was significantly positive and ranged from moderate to high between growth traits (0.47–0.68) and between wood density traits (0.42–0.83) and non-significant between growth and wood density (-0.22–0.30) traits. An analysis of different radial positions showed that heritability tended to increase from pith to the bark position. Our results show a lower environmental effect on wood density traits, allowing the possibility of selecting superior provenances and families with high wood quality in breeding programs in both sites.

Tree species that ‘live slow, die older’ enhance tropical peat swamp restoration: Evidence from a systematic review

Abstract Degraded tropical peatlands lack tree cover and are often subject to seasonal flooding and repeated burning. These harsh environments for tree seedlings to survive and grow are therefore challenging to revegetate. Knowledge on species performance from previous plantings represents an important evidence base to help guide future tropical peat swamp forest (TPSF) restoration efforts. We conducted a systematic review of the survival and growth of tree species planted in degraded peatlands across Southeast Asia to examine (1) species differences, (2) the impact of seedling and site treatments on survival and growth and (3) the potential use of plant functional traits to predict seedling survival and growth rates. Planted seedling monitoring data were compiled through a systematic review of journal articles, conference proceedings, reports, theses and unpublished datasets. In total, 94 study‐sites were included, spanning three decades from 1988 to 2019, and including 141 indigenous peatland tree and palm species. Accounting for variable planting numbers and monitoring durations, we analysed three measures of survival and growth: (1) final survival weighted by the number of seedlings planted, (2) half‐life, that is, duration until 50% mortality and (3) relative growth rates (RGR) corrected for initial planting height of seedlings. Average final survival was 62% and half‐life was 33 months across all species, sites and treatments. Species differed significantly in survival and half‐life. Seedling and site treatments had small effects with the strongest being higher survival of mycorrhizal fungi inoculated seedlings; lower survival, half‐life and RGR when shading seedlings; and lower RGR and higher survival when fertilising seedlings. Leaf nutrient and wood density traits predicted TPSF species survival, but not half‐life and RGR. RGR and half‐life were negatively correlated, meaning that slower growing species survived for longer. Synthesis and applications. To advance tropical peat swamp reforestation requires expanding the number and replication of species planted and testing treatments by adopting control vs. treatment experimental designs. Species selection should involve slower growing species (e.g. Lophopetalum rigidum, Alstonia spatulata, Madhuca motleyana) that survive for longer and explore screening species based on functional traits associated with nutrient acquisition, flooding tolerance and recovery from fire.

Combining Quantitative Data on Growth, Wood Density and Other Traits with SSR Markers to Evaluate Genetic Diversity and Structure in a Planted Population of Eucalyptus camaldulensis Dehn.

Eucalyptus camaldulensis Dehn. is one of the most morphologically and genetically variable Eucalyptus species. Growth, Leptocybe invasa Fisher & La Salle susceptibility, pilodyn penetration and other traits up to age 36 months were assessed in a seed source/family trial in China comprising 112 seedlots representing five natural stand and six exotic seed sources. Genetic diversity and population structure of this trial population were also analyzed using 48 simple sequence repeat (SSR) markers. The key objective was to examine whether the genomic data could provide value over information obtained from just quantitative trait data. Significant genetic variation was found among seed sources and among families within seed sources for most quantitative traits. The ratio of variance among seed sources to variance among families within seed sources, based on variances estimated from quantitative trait data, varied from 0.1% (height at 9 months) up to 75.2% (bark thickness). Equivalent ratios estimated from the AMOVA on SSR loci data were similar for height (ages 24 and 36 months) and also pilodyn penetration at 36 months, but not for 9-month height or 36-month bark thickness. From 48 SSR loci examined, the genetic differentiation coefficient (among seed sources) was 0.086, indicating low genetic differentiation among seed sources. While overall genetic diversity in the trial population examined was high, the levels within the different seed sources varied markedly. Prior to this study, genetic distances among families from the three exotic seed sources (from domesticated Indian populations) in the trial, along with their genetic distances from, and relatedness to, families from five natural stand seed sources (Australian) in the trial were unknown. The SSR loci data removed uncertainties and revealed that the exotic sources increased the breadth of genetic origins represented in the trial population—information that could not have been obtained from just the quantitative trait data.

Intra-specific variation in growth and wood density traits under water-limited conditions: Long-term-, short-term-, and sudden responses of four conifer tree species

Consequences of climate change will severely affect forest ecosystems in the near future, yet our understanding of how and why trees are responding to their abiotic environment is still limited. Intra-specific variation (ITV) in the growth response of trees to warming and drought has been widely neglected so far, but could play a key role for adapting forests to future climate conditions. We analyzed tree rings from four conifers (Picea abies, Abies alba, Larix decidua, Pseudotsuga menziesii) regarding their intra-specific adaptation potential when trees are growing at the warm and dry margins of species distributions. Our study comprises data from four common garden experiments (45 provenances and a total of 743 trees) and assessed growth response at different temporal scales from decades (long-term) to only a few event years (short-term) and finally for density fluctuations within one year (sudden response). We observed significant variation among provenances at all time-scales, but with varying degree among species. However, variation in short-term response (drought years) was remarkably unstable across all species, when the seasonal variation of drought occurrence was considered. Silver-fir and Douglas-fir showed significant associations between seed-source climate and growth response as well as trade-offs between early- and latewood growth reaction which strongly suggests that growth responses are adaptive. Intra-specific variation in conifers in response to drought will probably be sufficient to mitigate climate change consequences on forest growth, but growth-environment interactions as well as dependencies between temporal scales could create major pitfalls for adaptive forest management in the future.

Do Common Silvicultural Treatments Affect Wood Density of Mediterranean Montane Pines?

Wood density is one of the most important and well documented wood quality attributes. However, studies focusing on the effects of thinning combined with pruning on wood density in Mediterranean areas are scarce, even though both are recommended practices in forests managed for the production of high-quality timber. We assess the effects of both silvicultural interventions on wood density traits (tree-ring, earlywood, and latewood) and on the percentage of latewood, on an annual scale, for the main timber species Pinus sylvestris L. and Pinus nigra Arnold (subsp. nigra and subsp. salzmannii) in Mediterranean mountains. To this end, three trials (one species per trial) were established in monospecific reforestations in the 1990s. Three silvicultural treatments were applied: thinning, thinning combined with pruning, and a control. At the time of installation, stand ages ranged from 26 to 37 years. Small differences were found among treatments in regard to the wood density attributes, with no significant effects of thinning and pruning on the studied wood traits in either timber species. The two subspecies of P. nigra presented comparatively denser wood than P. sylvestris. Our results suggest that thinning and pruning treatments can be applied without causing unfavourable changes to wood density.

Differences in growth and wood density in clones and provenance hybrid clones of Norway spruce

The growing forest bioeconomy calls for enhancing wood production in Finland. Accordingly, we studied phenotypic differences and correlations for growth and wood density traits in 25 Norway spruce (Picea abies (L.) Karst.) genotypes grown in a field trial established in the 1970s in southeastern Finland. We also studied the effect of the geographical origin of parent trees. The clones represented six southern Finnish and two southwestern Russian clones and three Finnish–Swiss, eight Finnish–German, three Finnish–Latvian, and three Finnish–Estonian hybrid clones. Some local Finnish clones (e.g., V43) and provenance hybrid clones (e.g., Finnish–German V449 and V381) clearly displayed higher stem volume than the average over all of the clones and relatively high overall wood density (and wood biomass yield). The increase in latitudinal transfer distance of parent trees compared with the latitude of the trial seemed to decrease the height, diameter at breast height, and stem volume, but the effect was not significant (p > 0.05). The overall wood density was affected significantly only by the latitude of the father parent trees (p < 0.05). Wood density traits showed clearly lower phenotypic variation compared with other traits. Contrary to our hypothesis, none of the studied hybrids showed superior properties compared with the local Finnish clones.

Wood density as a proxy for vulnerability to cavitation: Size matters

In this study, vulnerability to cavitation, P50 (i.e. the water potential causing 50 % loss of hydraulic conductivity), of Norway spruce trunkwood at different cambial age was related to wood density. Wood density was calculated from mass in the oven dry state related either to volume at the oven-dry state (dry wood density) or to volume at full saturation (basic wood density). Dry wood density and basic wood density were strongly linearly related (r² = 0.99); there was however a shift from the 1:1 reference line with increasing dry wood density. Dry wood density as well as basic wood density had similar high predictive qualities for P50 (r² = 0.85). The quadratic regression lines took however a quite different course below -4 MPa because volume shrinkage increased with increasing dry wood density. For Norway spruce sapwood with high dry wood density, mixing up different wood density traits would thus result in a predicted overestimation or underestimation of vulnerability to cavitation. Gravimetrically wood density measurements at different moisture contents (starting at full saturation) are easily to achieve on standard size specimens and the conversion curves obtained will be of high value for future ecological studies on other species and across species.

Woody Plants of Tamaulipan Thorn Scrub: Morphology, Wood Anatomy and Ecophysiology

During last three to four years we studied various aspects of woody plant species in Forest Science School, Universidad de Nuevo Leon, UANL, Mexico. The present study describes salient characteristics of habitat, leaf morphology, wood anatomy, wood density and few eco-physiological traits of major woody plant species of Tamaulipan Thornscrub, at Linares, Northeastern Mexico. This will serve as guide to know about all these traits for the students, researchers and foresters to unveil the various aspects of these woody species of high economic importance and ecological importance.

Within-stem variation in wood properties of triploid hybrids of Populus tomentosa at three clonal trials

To obtain a better understanding of variability in wood properties along the stem in triploid hybrids of Populus tomentosa L., basic wood density (BWD) and fiber traits were measured at four sample heights for each tree sampled from three clonal trials. The BWD showed a similar trend at each site in that density was initially decreased then increased with increasing height position. For fiber traits, the fiber length (FL) decreased linearly with the height of the trunk, whereas fiber width and coarseness changed relatively slightly with increasing height position. In addition, the vertical wood properties distribution patterns were different from clones so that some clones showed more markedly change in height positions than others. The joint analysis indicated significant height position effect for BWD and fiber traits, in accordance with site and clonal effect. Significant site × height interaction was found on wood properties, whereas the significant clone × height interaction was only obtained at fiber width. Moreover, variation in the relationships between FL and BWD or other fiber traits showed no consistent pattern with increasing height position.

Provenance Variation in Radial Increment and Wood Characteristics Revealed by 30 Years Old Norway Spruce Comparative Trials

AbstractThe performance of 33 Norway spruce [Picea abies (L.) Karst.] seed sources from the Romanian Carpathians was evaluated with respect to growth and wood characteristics in comparative trials located at two different site conditions: Avrig- outside of the natural range of Norway spruce and Bret¸cu - within the natural range of this species. The radial increment (RI), latewood percentage (LWP) and conventional wood density (CWD) traits were evaluated at age 30 years after plantation. Phenotypic correlations between the evaluated traits, on the one hand, and between the same traits and the geographic gradients of the origin of seed sources, on the other hand, were calculated. Analysis of variance showed significant (p<0.01) differences between seed sources for RI, while for LWP and CWD, the differences were highly significant (p<0.001). These results suggest that selection at seed sources level could be possible. The test sites influence the LWP and CWD, while the RI is almost similar in both sites. For RI, the most valuable populations are situated in the Eastern and Western Romanian Carpathians. The highest LWP was registered for the Eastern Carpathian populations, while the lowest was recorded for the Western Carpathian populations. The Southern Carpathian populations, characterized by a lower growth rate, had higher values for wood density.

Variations in the radial growth and wood density components in relation to cambial age in 30-year-old Pinus brutia Ten. at two test sites

Radial growth and wood density are important traits in assessing wood quality. Our objective was to investigate patterns of variation of radial growth (ring width, earlywood width, latewood width, latewood proportion) and wood density (ring average density, earlywood density, latewood density) components in a 30-year-old Pinus brutia at two test sites in Turkey. Wood increment cores at a height of 1.30 cm (dbh) from 1,010 trees at age 30 years were evaluated at two test sites. The radial growth and wood density traits of the individual rings were measured using X-ray densitometry. The test sites showed statistically significant differences in the radial growth traits but not in the wood density traits, suggesting that the wood density traits are less subject to environmental changes. The ring average density was relatively low (485 kg/m3) at early cambial ages (near the pith) and increased to 501 kg/m3 at later cambial ages (near the bark). The latewood density was 550 kg/m3 near the pith, increased steadily to 630 kg/m3 at cambial age 12, and remained stable thereafter. In contrast, the earlywood density and latewood proportion were highest near the pith. The twelfth ring from the pith appeared to represent the transition from juvenile to mature wood. The unique relationships among early and latewood densities and latewood proportion in the juvenile and mature wood contribute to more uniform wood both within a given annual ring and between the juvenile and mature portions of the stem in P. brutia. Thinning increased the ring width, latewood proportion, and ring average density.

Xylem function and climate adaptation in Pinus

The distribution of species is determined in part by their functional traits. One important function is the ability of xylem to supply water to leaves and withstand water-stress-induced cavitation. These hydraulic traits are hypothesized to have evolved in response to selection by precipitation and temperature. • We grew 26 species in the genus Pinus in a common environment and used phylogenetic comparative methods to examine whether the evolution of seedling hydraulic and wood density traits were associated with the climate of the extant geographic range of the species. We also examined whether these traits were correlated with each other, with integrated water-use efficiency (WUE), and with plant growth. • Contrary to predictions from a hydraulic model, we found no association between stem hydraulic conductivity (K(S)) and precipitation, even though there was substantial variation for K(S) in the genus. Nevertheless, K(S) was positively correlated with temperature, plant biomass, and WUE. Wood density was infrequently associated with climate or correlated with other traits except for plant biomass. • Reduced K(S) in cold climates, if associated with reduced conduit diameter, likely evolved to increase resistance to freezing-induced xylem cavitation. The absence of a K(S)-precipitation relationship among Pinus seedlings suggests that associations between hydraulic traits and precipitation found in adult trees arise through plastic responses to moisture availability and/or develop over ontogeny. The weak association among wood density, climate, and other traits suggest that this trait does not contribute to climate adaptation in Pinus.

Effects of propagule type on genetic parameters of wood density and growth in a loblolly pine progeny test at ages 10 and 11 years

Nine full-sib families of loblolly pine (Pinus taeda L.) were produced by a 3 × 3 factorial mating design. Rooted cuttings and seedlings of full-sib families were tested together in two field locations. Twelve-millimeter wood increment cores were collected from 10- and 11-year-old test trees. On each of the two sites, there were six blocks and a split-plot design, with propagule type as the whole plot and family as the sub-plot. In addition to the collection of wood samples, height and diameter of 1,600 trees were measured. No significant differences were found between cuttings and seedlings for wood density and growth traits. Significant family variation was found for growth and wood density. Genetic parameters estimated for wood density and growth traits using seedlings and rooted cuttings showed that individual-tree and family heritability estimates from rooted cuttings were similar to or higher than those from seedlings for all traits. Half-sib breeding values for parents were highly correlated based on seedling and rooted cutting estimates for height (0.95) and wood density (0.99) but not for diameter (0.56), which suggests that wood density and height breeding value estimates from rooted cuttings in clonal progeny tests can be estimated by traditional seedling tests, but not for tree diameter.

Differences in Fiber Properties and Basic Wood Density in Triploid Hybrids of Populus Tomentosa

In forest breeding programs, growth has typically been used as a selection trait of prime importance inPopulus tomentosa,whereas less attention has been given to fiber characteristics and basic wood density. Given this context, we investigated phenotypic relationships between different fiber properties, growth and basic wood density traits in nine triploid clones and one diploid clone based on a clonal trial established in 2004 in northern China. We found that fiber width showed, on average (1.4%), the lowest phenotypic variation followed by fiber length (2.2%), coarseness (5.3%). Basic wood density showed, on average (1.9%) phenotypic variation. All phenotypic correlations between fiber properties were positive (p＜0.05), ranging from moderate to strong, suggesting that selection for one trait could simultaneously affect other traits. Phenotypic correlations, on average, were quite weak but positive between growth and fiber properties and slightly negative between basic wood density and different fiber properties (p＜0.05). Individually, some of the triploid clones showed negative correlation between growth traits and fiber length. As a result, selection for fiber properties alone could reduce overall stem volume and would not directly indicate basic wood density traits and vice versa.

Effects of genetic entry and spacing on growth and wood properties in Scots pine

In forest breeding, stem volume and sawn timber quality have typically been used as the most important selection traits. Less attention has been paid to wood density and fibre properties. This study investigates the effects of genetic entry and spacing on the growth and yield traits, branch characteristics, wood density traits and fibre properties in 20-year-old Scots pines (Pinus sylvestris L.). Additionally, the phenotypic variation within, and correlations between, different traits and the effects of cambial age, spacing, genetic entry and climatic variables on the ring width and ring density development from pith to bark are studied. Kanerva pine (Finnish plus tree S1101) was the father tree for most of the genetic entries included in this study, whereas the mother trees represented Finnish plus trees with a relatively wide geographical range from northern to southern Finland. The effects of genetic entry (mainly full-sib families) and spacing on the growth and yield traits, wood density traits and fibre properties were analysed (Papers I-II) based on materials, harvested in 2006, from 10 genetic entries grown in a spacing trial in central Finland, with a current stand density range of 2000-4000 trees/ha. Furthermore, additional material was harvested from the same trial in 2008 to study the effects of genetic entry and spacing on the branch characteristics (Paper III) and the effects of cambial age, spacing, genetic entry and climatic variables on the ring width and ring density development from pith to bark (Paper IV). In this study wood density traits show lower phenotypic variation compared to growth and yield traits, regardless of spacing. Wood density traits present from moderate to strong phenotypic correlations among them (Paper I). Spacing affects significantly (p<0.05) all the yield traits, wood density traits and fibre properties (Papers I-II). Furthermore, spacing affects living branch characteristics such as relative average branch diameter and relative cumulative branch area (Paper III). Genetic entry affects tree height, wood density traits and fibre length (Papers I-II). When grouping the Kanerva tree crossings into different geographical origins based on their mother trees, the northern ones have, on average, the largest diameter at breast height and the highest mean wood density, while the central ones have the tallest trees (Paper III). Branch diameter along the stem is affected by branch age, geographical origin group and spacing, while branch angle is affected by branch age and genetic entry (p<0.05). Radial growth and ring density development are both affected by cambial age and spacing, and the latter is also affected by origin group and several climatic variables. The phenotypic correlations between various growth, yield and wood density traits are negative, which suggests that selection for one trait would simultaneously affect the other traits. The phenotypic correlations between different fibre properties are strong, but not well correlated with growth, yield and wood density traits. This kind of information is currently needed for breeders for considering different traits as selection criteria for tree breeding in Scots pine.

Differences in branch characteristics of Scots pine (Pinus sylvestris L.) genetic entries grown at different spacing

• We studied the differences in branch characteristics along the stems of six different genetic entries of 20 year old Scots pines (Pinus sylvestris L.) grown at different spacing (current stand density range 2000–4000 trees ha−1) in central Finland. Furthermore, we studied the phenotypic correlations between yield, wood density traits and branch characteristics. All the genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland. • Spacing affected all yield traits, wood density and living branch characteristics such as relative average branch diameter and relative cumulative branch area (p < 0.05). As a comparison, genetic entry affected height, while origin group (southern, central and northern ones) affected most of the studied traits. Regardless of spacing, the northern origin had, on average, the largest stem diameter and highest wood density, while the central one was the tallest one. Furthermore, average branch diameter along the stem was affected by branch age, origin group and spacing, while average branch angle was affected by branch age and genetic entry (p < 0.05). • In general the average branch size could be decreased especially in lower tree canopy by denser spacing during the early phase of the rotation, but only at the expense of tree growth. Correspondingly differences between origins are mainly related to their differences in stem growth.

Differences in growth and wood density traits in Scots pine (Pinus sylvestris L.) genetic entries grown at different spacing and sites

In forest breeding, stem volume has typically taken as the most important selection trait, whereas less attention has been given to wood density traits. In this work, we investigated the effects of spacing and genetic entry on the growth, yield and wood density traits in 20 year old Scots pines (Pinus sylvestris L.) based on 10 genetic entries harvested from a spacing trial (stand density range 2000–4000 trees/ha) in central Finland. In order to study also the site effects, we harvested additional material from a trial located in southern Finland (stand density of 2000 trees/ha). Compared to growth and yield properties, wood density traits showed a lower phenotypic variation. Phenotypic correlations among different traits were negative, and mostly moderate to high, suggesting that selection for one trait would simultaneously affect the others. In addition, moderate to strong phenotypic correlations were found among different wood density traits. Stem volume (V) and breast height diameter (DBH) were the largest in widest spacing, whereas in the densest one tree height (H) and latewood percentage were the highest. Genetic entry affected H and wood density traits regardless of spacing. When comparing two sites (with same stand density), genetic entry affected H, whereas site affected DBH and wood density traits. Ranking between genetic entries changed depending on the trait, spacing or site considered. Therefore, no overall ranking was possible. However, we could identify genetic entries having a high V and a relatively high wood density, showing potential for future forest regeneration material.

Growth and wood property traits in narrow crowned Norway spruce (Picea abies f. pendula) clones grown in southern Finland

We investigated the growth, yield, wood density traits and fibre properties in 13 narrow crowned Norway spruce (Picea abies f. pendula) clones grown at a spacing of 2 m x 1.5 m (about 3300 seedlings/ha) in a field trial established in 1988 in southern Finland on a forest soil. For comparison, we used 3 normal crowned Norway spruce (Picea abies (L.) Karst.) genetic entries grown as a mixture in the same trial representing southern Finnish breeding regions. We found that wood density traits and fibre properties showed, on average, lower phenotypic variation than growth and yield traits regardless of crown type. Narrow crowned clones also had, on average, lower stem volume and fibre length, but higher overall wood density. More over, the phenotypic correlations between studied growth and wood properties ranged, on average, from moderate (normal crown) to high (narrow crown). These results were opposite to previous findings for narrow and normal crowned genetic entries grown in narrower spacing (1 m x 1 m) in southern Finland. Thus, this indicates lower plasticity of narrow crowned clones to the increasing growing space compared to normal crowned ones, so, they should be grown at denser spacing in order to fully utilise its space efficiency capacity. However, this field trial was established as a mixture of normal and narrow crown trees, so that 90% of genetic entries were narrow crowned ones, and therefore the crown competition would be much higher for normal crowned trees when the whole trial would consist of that entry alone. In the latter case, we could expect significantly lower productivity of normal crowned genetic entries with this spacing.

Effects of genetic entry and competition by neighbouring trees on growth and wood properties of cloned Norway spruce (Picea abies)

• The aim of this work was to study both the effects of genetic entry and competition by neighbouring trees on growth, yield, wood density traits and fibre properties of 20 Norway spruce clones grown in an experimental trial located in southern Finland. The material included 10 Finnish clones, 2 Russian clones and 8 provenance-hybrids clones, the latter ones representing crosses between Finnish and foreign parent trees. • We found that, compared to growth and yield, wood density traits and fibre properties showed, on average, lower phenotypic variations. Moreover, significant differences could be observed among the clones regardless of the trait (p < 0.05). Conversely, on average, no clear differences could be found between Finnish, Russian and provenance-hybrids clones in most of the studied traits. • The marked differences among the clones, and lack of clear differences among the provenances suggested that any ranking, regarding different traits, should be based on individual clones. The phenotypic correlations between different traits ranged from moderate to strong suggesting that selection based on one trait would affect other traits. Regardless of clone, the growth of trees (e.g. breast height diameter) decreased and the wood density increased with increasing competition by neighbouring trees, which was expressed by competition index.