Larch Species Research Articles

Do biomass partitioning and growth efficiency contribute to growth heterosis in inter-specific hybrid larchLarix x eurolepis?

AbstractHybrid larch (Larix decidua x L.kaempferi) is a fast growing species with high potential for reforestation outside the native range of European larch. Its superiority over its parents is well documented but still today little is known about the genetic background of heterosis and even less about the physiological mechanisms supporting it. In this paper, we hypothesize that a different allocation of biomass and/or growth efficiency could explain growth differences between larch species. To examine heterosis sensu stricto, we used a subset of progeny from an intra−/inter-specific diallel-mating design represented by connected pedigrees from the three species (Hybrid larch, European larch and Japanese larch). Six years after planting, we harvested the trees, excavated roots and measured dry weights of above- and belowground parts. The best allometric relationships were determined for predicting the biomass of each compartment. Heterosis for stem volume exceeded 108 per cent and 81 per cent for total tree biomass over mid-parent values. Hybrid superiority was visible for all biomass compartments and particularly for needles and branches, so that aboveground biomass heterosis reached 2.5 times that for the roots. In addition to a greater biomass, the hybrid benefited from a modified allocation of biomass with a slightly higher proportion of branch and needle biomasses and a reduced proportion of root biomass. Hybrid and European larches had a significantly greater growth efficiency than Japanese larch. Whereas the differential of productivity between European and Japanese larch did not increase with size, it greatly increased for hybrids with fine root mass increase. A heavier crown, a reduced proportion of root biomass and greater root efficiency in hybrid larch should enhance photosynthesis and reduce root respiration cost, providing more carbon-based resources for use in stem wood production. Implications for breeding are briefly discussed.

Зимостойкость хвойных растений в условиях северной лесостепи юга Тюменской области

We have studied 4 species of the genus fir, 3 species of the genus spruce (including (hereinafter) 14 varieties of Norway spruce and 12 varieties of blue spruce), 2 species of the genus larch (3 varieties of Western European larch), 7 species of the genus pine (7 varieties of mountain pine and 12 varieties of northern white cedar), 6 species of the genus juniper (3 varieties of common juniper, 5 varieties of savin juniper, a variety of Rocky Mountain juniper, 3 varieties of flaky juniper, 2 varieties of Virginian juniper and 3 varieties of Juniperus pfitzeriana) and a species of Siberian carpet cypress. All the studied plants were divided into three groups: highly promising, less promising and unpromising for this region. Most plants from the first group have large habitats indicating a wide range of their ecological potential. It has been found that the use of plants from the second group requires a careful selection of suitable locations and great attention to care measures. Plants from the third group are unpromising. It is impractical to use them actively in landscaping. The analysis also resulted in the development of a method for selecting coniferous plants for landscaping in the northern forest steppe of the south of the Tyumen region, based on their size parameters, species, varieties and needle colour. There are also 4 groups based on height: procumbent, scrubby, medium-grown, and tall-grown. Each group is divided into 3 subgroups based on the color of the needles: green, yellowish and caesious. The size of the plant has to be taken into account when creating ornamental plantations. Thus, fastgrowing varieties are useful for short-term decorative effects or in places where wind or noise protection is required fairly quickly. Medium-grown species are suitable for landscaping any territories and, with the use of restrictive pruning, even for small gardens or topiary art. Scrubby plants are suitable for landscaping small gardens, rockeries, small compositions. Depending on their growth rate, groundcover plants can be used as a lawn replacement, to stabilize slopes and create a carpet effect. For citation: Lyasheva L.V., Lyashev A.A., Steinberg Yu.S. Winter Hardiness of Conifers in the Northern Forest Steppe Conditions of the South of the Tyumen Region. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 49–61. DOI: 10.37482/0536-1036-2022-1-49-61

Дифференциация климатипов лиственниц (Larix spp.) в географических культурах в лесостепи Средней Сибири

Дифференциация климатипов лиственниц (Larix spp.) в географических культурах в лесостепи Средней Сибири

Occurrence status of needle cast of larch species sapling in plantation in relation to leaf nutrition balance

Occurrence status of needle cast of larch species sapling in plantation in relation to leaf nutrition balance

Botanical-geographical differentiation and succession systems on the territory of the Republic of Bashkortostan

On the territory of the Republic of Bashkortostan the main regularities of landscape differentiation are manifested latitudinal zoning, altitudinal zoning and the barrier effect, which determine the territorial differentiation of the vegetation cover. The existing schemes of botanical-geographical and geobotanical zoning reflect these patterns. The largest zoning units are zonal structures (forest, forest-steppe and steppe regions), within which, on the basis of geological and geomorphological features, smaller taxonomic units are distinguished provinces, areas, districts. The zoning method proposed by S.M. Razumovsky which is based on the concept of a succession system is of interest. According to this concept, the vegetation cover of the Earth is divided between succession systems. The boundaries of successional systems are outlined by the boundaries of the geographical areas of key species edificators of indigenous forest phytocenoses. S.M. Razumovsky presented a scheme of botanical-geographical zoning, made on a small scale. The boundaries of succession systems, with the exception of some areas, are not delineated. The author set a goal: to determine a list of succession systems common on the territory of the Republic of Bashkortostan, to outline their boundaries and give their brief characteristics. As a result of literary sources study and analysis, the author has come to the conclusion that 4 succession systems are widespread on the territory of the Republic of Bashkortostan: 1) broad-leaved-dark coniferous forests with climax species of Siberian spruce, Siberian fir, pedunculate oak, heart-leaved linden and Norway maple; 2) dark coniferous forests, with climax species of Siberian spruce and Siberian fir; 3) broad-leaved forests with climax species of pedunculate oak, heart-leaved linden and Norway maple; 4) light coniferous forests with sub-climax species of Scots pine and Sukachev larch.

Differences in growth pattern and response to climate warming between Larix olgensis and Pinus koraiensis in Northeast China are related to their distinctions in xylem hydraulics

Tree-ring analysis provides an effective way to detect complex responses of trees to climate warming and has been extensively used in ecological studies; however, there is often a lack of simultaneous physiological investigations explaining the observed patterns. Here, we paralleled dendroclimatic analyses with hydraulics measurements in co-occurring Larix olgensis and Pinus koraiensis trees along an elevational gradient (low, middle and high) in Northeast China. We aimed to detect potential differences in patterns of growth and responses to climate warming between the two conifer species considering their distinctions in life history strategy and key functional traits and to provide a mechanistic explanation for such differences. Our tree-ring analyses showed that L. olgensis trees exhibited a linear increase in basal area increment at the initial part of lifetime while Korean pine trees usually have a long slow growth period up to several decades at the juvenile stage. Consistent with their contrasts in growth rate, the larch species showed significantly higher hydraulic conductivity and functional traits favoring more efficient carbon gain at the shoot level compared to sympatric Korean pine trees. Results of the dendroclimatological analyses indicate that temperature rather than precipitation is the controlling factor for growth in both species under the current climate regime. Radial growth of both species overall accelerated accompanying the rapid warming since 1990s except a significant decrease in growth for Korean pine trees at the low elevation site, which is likely due to stronger competitions from co-occurring broadleaf trees in the mixed forest environments. In the larch species, the substantially lower degree of response in growth at the low elevation site compared to trees at higher elevations suggests that the drying effect of warming at the low elevation may have to a certain degree offset the beneficial effects of warming on growth of larch trees.

Наследственная обусловленность пигментного состава хвои представителей рода лиственница

The content and ratio of plastid pigments in the conifers of three species of the larch genus (Larix Mill.) were studied: Siberian larch (L. sibirica Ledeb.), Gmelin’s larch (L. Gmelinii (Rupr.) Rupr.), Sukachev’s larch (L. Sukaczewii Dylis). Their seed progeny is concentrated on a pilot site in the Sergachsky forestry of the Nizhny Novgorod region with geographical coordinates 55°32 ‘14,2” N 45°28’01,0” E and an absolute height of 160 m. The site is assigned to the zone of coniferous-broad-leaved forests (the third forest-growing zone) and is included in the area of coniferous-broad-leaved (mixed) forests of the European part of the Russian Federation. The content of chlorophyll a, chlorophyll b and carotenoids in the needles was determined by spectrophotometric method at wavelengths: 665 nm, 649 nm, 452,5 nm. Samples for research were prepared in accordance with the principle of a single logical difference and randomized sample formation. Phenotypic differences in the pigment composition of needles between representatives of these species were revealed. The pigment composition of Siberian larch is dominated by chlorophyll a (3,76 ± 0,12 mg/g), significantly less chlorophyll b (1,87 ± 0,07 mg/g) and even less carotenoids (0,59 ± 0,02 mg/g). The same is observed in the pigment composition of other larch species. The hereditary conditionality of the species specificity of Siberian larch, Gmelin’s larch and Sukachev’s larch was established for all the tested characteristics. The greatest influence (29,84 ± 1,61 %) on the formation of the total phenotypic dispersion was observed in the ratio of the content of chlorophyll-a to the content of carotenoids, the least (5,89 ± 2,16 %) — in the content of dry matter in the needles. Relatively high values were obtained for the proportion of carotenoids (26,74 ± 1,68 %) and the ratio of their content to the total of chlorophylls (26,39 ± 1,69 %). The studied species showed an unequal level of similarity or significant differences in the individual characteristics of the pigment composition of needles.

Oxygen Isotope Compositions of Cellulose in Earlywood of Larix cajanderi Determined by Water Source Rather Than Leaf Water Enrichment in a Permafrost Ecosystem, Eastern Siberia

AbstractThe oxygen isotopic composition of tree‐ring cellulose (δ18Ocell) has been widely used to reconstruct historical environmental changes; however, the control factors on δ18Ocell have not been fully constrained—especially in high latitudes. To evaluate the influence of metabolic processes and related environmental factors on δ18Ocell, we analyzed the δ18O values of soil water (1998–2015), stem water (1997–2016), leaf water (3 days in each 2014 and 2015), and tree‐ring cellulose (1981–2016), on a dominant larch species (Larix cajanderi) in an eastern Siberian boreal forest. We determined that the δ18O variability of water sources is dependent on the precipitation, and the 18O enrichment in leaf water is determined by relative humidity. These findings suggest that both water source uptake and leaf water enrichment processes can affect the δ18O values of oxygen‐containing compounds in larch trees in the study site. However, the δ18Ocell (one of the end oxygen‐containing products) was found dependent on water sources on which was related to the amount of summer rainfall in the previous year. This finding significantly differs from that of studies in other areas, which infer the positive correlation between δ18Ocell and leaf water enrichment rather than precipitation or water sources. These differences are predominantly due to the specific conditions of high‐latitude areas, such as the large seasonal δ18O difference in precipitation, the existence of permafrost, and the low growth rate. Our findings contribute toward the development of tree‐ring paleoclimate reconstructions—especially in eastern Siberia.

Physiological and anatomical responses to drought stress differ between two larch species and their hybrid

Key MessageHybrid saplings were more reactive to soil water deficit than Japanese and European larch. European larch had hydraulically safer wood and anisohydric behavior, Japanese and hybrid larch showed isohydric strategy.Deciduous larch species could be an alternative to evergreen conifers in reforestation, but little is known about drought sensitivity of their saplings. The effect of an experimental drought on hydraulics and quantitative wood anatomy was tested on saplings of European larch (EL, Larix decidua), Japanese larch (JL, Larix kaempferi) and their hybrid (HL). Across species, biomass, transpiration rate and relative water content were higher in controls than in drought stressed trees, but transpiration efficiency was lower. JL had the highest transpiration efficiency under drought, and EL the lowest, coinciding with slower growth of EL. Wood of EL formed before drought was hydraulically safer as shown by higher wall/lumen ratio and lower pit cavity area. EL neither had a significant increase in transpiration efficiency nor a reduction in transpiration rate under drought, suggesting that the stomata remained open under soil water deficit. HL saplings were the most reactive to water shortage, indicated by intra-annual density fluctuations and a decrease in relative water content of the sapwood. Significant reduction in transpiration by HL suggested a higher stomatal sensitivity, while the same leaf surface area was maintained and radial growth was still similar to its best parent, the JL. The latter showed a significantly lower leaf surface area under drought than controls. EL, with its hydraulically safer wood, followed an anisohydric behavior, while JL and HL revealed an isohydric strategy. Altogether, our results suggest species dependent acclimations to drought stress, whereby HL followed the strategy of JL rather than that of EL.

Сравнительный анализ изменчивости формы семенных чешуй шишек Larix dahurica и L. cajanderi (Pinaceae)

Сравнительный анализ изменчивости формы семенных чешуй шишек Larix dahurica и L. cajanderi (Pinaceae)

Assisted migration poleward rather than upward in elevation minimizes frost risks in plantations

When assisted migration is used to address climate change, tree seedlings may have to be moved to substantially colder environments in anticipation of climate warming over their life span. Here, we evaluate frost risks for four economically important forest tree species of western Canada, Douglas-fir (Pseudotsuga menziesii), lodgepole pine (Pinus contorta), interior spruce (Picea glauca, P. engelmannii, and their hybrids), and western larch (Larix occidentalis), when moved to adjacent northern and higher elevation seed zones that are cooler by approximately 2 °C. Changes to risks of damaging frosts among seed zones are evaluated during two 30-day periods, after dormancy release in spring and before onset of dormancy in fall, assuming a temperature-dominated day of bud break and a critical photoperiod-controlled onset of dormancy in fall. Based on daily interpolated climate data between 1980 and 2019, we find that late spring and early fall frost risks do not change significantly for transfers toward the north (<1 percentage point in most cases). In contrast, moving planting stock toward higher elevation generally leads to a substantial increase in exposure to unseasonal frosts (late spring frosts: 0.5% to 9.4%, early fall frosts: 0.8% to 17.1%). We conclude that transfers toward the north are preferable to transfers up in elevation in reforestation of these tree species in western Canada.

Contribution of Xylem Anatomy to Tree-Ring Width of Two Larch Species in Permafrost and Non-Permafrost Zones of Siberia

Plants exhibit morphological and anatomical adaptations to cope the environmental constraints of their habitat. How can mechanisms for adapting to contrasting environmental conditions change the patterns of tree rings formation? In this study, we explored differences in climatic conditions of permafrost and non-permafrost zones and assessed their influence on radial growth and wood traits of Larix gmelinii Rupr (Rupr) and Larix sibirica L., respectively. We quantified the contribution of xylem cell anatomy to the tree-ring width variability. Comparison of the anatomical tree-ring parameters over the period 1963–2011 was tested based on non-parametric Mann-Whitney U test. The generalized linear modeling shows the common dependence between TRW and the cell structure characteristics in contrasting environments, which can be defined as non-specific to external conditions. Thus, the relationship between the tree-ring width and the cell production in early- and latewood are assessed as linear, whereas the dependence between the radial cell size in early- and latewood and the tree-ring width becomes significantly non-linear for both habitats. Moreover, contribution of earlywood (EW) and latewood (LW) cells to the variation of TRW (in average 56.8% and 24.4% respectively) was significantly higher than the effect of cell diameters (3.3% (EW) and 17.4% (LW)) for the environments. The results show that different larch species from sites with diverging climatic conditions converge towards similar xylem cell structures and relationships between xylem production and cell traits. The work makes a link between climate and tree-ring structure, and promotes a better understanding the anatomical adaptation of larch species to local environment conditions.

GEOMETRIC MORPHOMETRIC ANALYSIS OF CONE SCALES FOR PHENOTYPIC DIFFERENTIATION OF LARIX SPECIES (PINACEAE)

Methods of geometric morphometrics were used to analyze differentiation of three larch species – Larix gmelinii, L. cajanderi, and L. sibirica, which are the most common larch species in North Asia, by the shape of the cone scales. The samples of seed-bearing scales of mature cones were collected from 185 trees in 8 populations, which represented the different regions of the Larix species areas. Ten outline points on one side of the cone scales were chosen to characterize their shape. Patterns of shape variation were depicted using Generalized Procrustes Analysis (GPA). PCA results of partial warps (PW) revealed the shape differences of cone scales among the three species of Larix. The CVA of relative warps (PCA scores) showed that the Larix species were all successfully discriminated, and populations within the species were considerably differentiated. Geometric morphometrics can be used as an effective tool to analyze inter- and intra-specific differentiation of Larix species based on the shape of cone scales.

Результаты изучения географических посадок сосны и лиственницы в Серебряноборском опытном лесничестве

The results of the cultivation of Scots pine (Pinus sylvestris L.) in the provenance trial in the Serebryanoborsky experimental forest district of the Institute of Forestry of the Russian Academy of Sciences are summarized. The silvicultural effect was assessed by a comprehensive indicator of the feasibility of introducing specific pine conventions. It was established that the use of pine seeds of exclusively local provenances cannot be considered justified. In the vast area of pine there are very remote populations of a local nature, the seed of which, when moved, can be successfully used to create highly productive artificial stands. The 68 year old geographical plantations of larch growth and production rates of 18 climotypes of 14 larch species were compared. These species are Polish larch (Larix polonica Racib.), European larch (Larix decidua Mill. f. Sudetica), Larix sukaczewii Dylis, Siberian larch (Larix sibirika Ledeb.), Larix cajanderi Mayr., Larix gmelinii Rupr., Larix Czekanovskii Szaf, Larix amurensis Kolesn., Olgan larch (Larix olgensis Henry), Japanese larch (Larix kaempferi (Lamb.) Carrière), Larix kurilensis Maur., Larix principis Rupprechtii Maur., Larix potaninii Bat, American larch (Larix laricina (Duroi) K. Koch). Polish larch, Japanese larch, European larch and Olgan larch have the best growth rate results. Climotypes from Siberia and American larch showed worst results. Polish larch (812 m3/ha) and Japanese (804 m3/ha) larch from the Southern Sakhalin have the highest stem volume. The final estimations showed that the climotypes of Polish larch, European larch from Sudetes and Japanese larch from the Southern Sakhalin are suitable for introduction in the Moscow Region. The climotypes from the Far East, namely Larix amurensis Kolesn., Olgan larch and Larix kurilensis Maur., had positive silvicultural effect. The inland climotypes from Asia together with American larch showed negative results.

Impacts of competition and nitrogen addition on plant stoichiometry and non-structural carbohydrates in two larch species

Previous research has shown that competition between plants can have differential effects on leaf stoichiometry and non-structural carbohydrate (NSC) in different environments. However, little attention has been given to understanding these effects on non-photosynthetic organs, particularly of deciduous tree species. Here we assess the impact of competition on below and aboveground biomass, stoichiometry, nutrient composition and NSC in pure and mixed forests of two Larch species, Larix kaempferi and L. olgensis under nitrogen (N) addition. Nitrogen enrichment did not result in stronger intraspecific competition for both species and L. olgensis benefited from the presence of L. kaempferi under different N levels. Stems kept relatively stable C/N compared to roots and branches in response to competition, while N addition imposed stronger impacts on N/P of different organs rather than competition. In contrast to stable C concentrations, starch and soluble sugar concentrations were more easily impacted by competition and the addition of nitrogen. Competition forced L. kaempferi and L. olgensis to allocate more carbon into storage by increasing their starch concentration and starch/soluble sugar of stems under competition. However, no significant differences in stoichiometry and NSC concentration between intra- and interspecific competition were found. NSC and nutrient pools of L. kaempferi stems, branches and coarse roots consistently declined due to competition regardless of N addition. Coarse and fine roots of L. kaempferi accumulated more N when in competition with L. olgensis than with a conspecific neighbor under N addition. Our results show that NSC was more sensitive to competition relative to stoichiometric traits (N and P) of non-photosynthetic organs.

Somatic embryogenesis in Larix: the state of art and perspectives.

Clonal propagation of conifers using somatic embryogenesis is essential for the selection of tree species, and for the implementation of afforestation and reforestation. In combination with cryopreservation, somatic embryogenesis creates the basis for the development of economically valuable lines of clones and elite genotypes. The industrial use of such genetically verified clone lines in forestry can significantly increase forest productivity compared to any conventional methods for improving tree crops that are available. Larch is considered as one of the main conifer candidates for large-scale reforestation, not only due to the vastness of its habitat, but also due to the unique quality of its wood, rapid growth and high ecological plasticity. However, the vast majority of larch species are characterized by uneven yields and extremely low seed quality. In this regard, obtaining planting material for reforestation from larch seeds on seed plantations is not advisable, but can be successfully implemented in afforestation programs using somatic embryogenesis technologies. Research on the somatic embryogenesis of larch has been conducted for over 30 years, which allowed considerable experience in this field to be accumulated. To date, the conditions for the initiation and maintenance of embryogenic cultures, as well as for the formation and development of somatic embryos have been determined. Significant progress has been made in the study of both the factors affecting these processes and the molecular mechanisms that underlie the various stages of embryogenesis. Nevertheless, despite the successes achieved, knowledge available today on the somatic embryogenesis of representatives of the genus Larix is still not enough to develop technologies for producing valuable plant-breeding material in vitro. This review analyzes the current state of research on the problem of somatic embryogenesis of representatives of the genus Larix. Particular attention is paid to the choice of explants for somatic embryogenesis, the composition of the media for cultivation, the dependence of the potential of somatic embryogenesis on the duration of cultivation, and the genetic control of somatic embryogenesis.

Tracing radioactive cesium in stem wood of three Japanese conifer species 3\xa0years after the Fukushima Dai-ichi Nuclear Power Plant accident

To understand the dynamics of accident-derived radioactive cesium (137Cs) in stem wood that had a substantial amount of heartwood at the time of the Fukushima Dai-ichi Nuclear Power Plant accident, the radial and vertical distributions of 137Cs activity concentration in stem wood of Japanese cedar (Cryptomeria japonica), cypress (Chamaecyparis obtusa), and larch (Larix kaempferi) were investigated. In addition, the natural distribution of stable cesium (133Cs), rubidium (85Rb), and potassium (39K) concentrations was analyzed to determine the characteristics of 137Cs distribution. Wood disks were collected from the tree stems of six cedars, three cypresses, and two larches at multiple heights in 2014, and the concentrations were measured every 2 cm in the radial direction. 137Cs distribution in stem wood differed among tree species, sampling site, and vertical position of the stem within a tree. Statistical analyses suggested that the radial distribution of 137Cs within the heartwood can be explained by the heartwood moisture content and the distance from the treetop, regardless of species, while the distribution between sapwood and heartwood was dependent on the heartwood cross-sectional area and was additionally different between larch and other species. Similarly, the heartwood/sapwood concentration ratios of stable alkali metals differed between larch and the other species. In the larch, the ratio was ca. 0.5 for all elements, but the ratio was over 1.0 and differed among elements in the other species. Consequently, the species-specific difference in the distribution of 137Cs between sapwood and heartwood was considered to be due to different activity levels of radial transport toward the heartwood. The radial variation pattern of the 137Cs/133Cs concentration ratio showed that less 137Cs was transferred to the inner heartwood compared with the 133Cs distribution pattern in many trees; however, there was also a tree in which 137Cs was excessively transferred to the inner heartwood compared with the 133Cs distribution pattern. Such patterns may result from a combination of significant foliar uptake of 137Cs and poor root uptake after the accident, in addition to the high moisture content of the heartwood.

Developing Ozone Risk Assessment for Larch Species

Ozone (O3) risk assessment for the protection of forests requires species-specific critical levels (CLs), based on either O3 concentrations (AOT40) or stomatal uptake (PODY) accumulation over the growing season. Larch (Larix sp.) is a genus with O3-susceptible species, widely distributed in the northern hemisphere and with global economic importance. We analyzed published and unpublished data of Japanese larch (L. kaempferi) and its hybrid F1 (L. gmelinii var. japonica × L. kaempferi) responses to O3 exposure for developing a parameterization of stomatal conductance model and estimating PODY-based CLs with two Y thresholds, i.e. 0 and 1 nmol m-2 s-1 PLA. In parallel, we estimated AOT40-based CLs. The results show that the AOT40-based CLs for a 2% and 4% biomass loss in Japanese larch were 5.79 and 11.59 ppm h, i.e. higher than in hybrid larch F1 (2.18 and 4.36 ppm h AOT40), suggesting a higher O3-susceptibility of the hybrid. However, the use of PODY reconciled the species-specific differences, because the CLs were similar; i.e. 9.40 and 12.00 mmol m-2 POD0 and 2.21 and 4.31 mmol m-2 POD1 in Japanese larch, vs. 10.44 and 12.38 mmol m-2 POD0 and 2.45 and 4.19 mmol m-2 POD1 in the hybrid, for 2% and 4% biomass loss, respectively. Overall, the CLs were lower than in other forest species, which suggests a relatively high susceptibility of these larches. These results will inform environmental policy-makers and modelers about larch susceptibility to O3.

Variation of larch wood property indexes based on nondestructive testing data

To quickly evaluate the material properties of ancient wooden structure members on site, the larch species of northeastern China was used as the research object, and the nondestructive testing method of the stress wave and the micro-drill resistance meter were used to measure it. The variation laws of the larch wood’s cross and longitudinal property indexes were determined. According to the variation law of material property indexes, the detection divisions under the nondestructive testing technology of stress wave and micro-drill resistance instruments were divided, which provides a basis for improving the accuracy of on-site nondestructive testing. From the comparison of shade and light side data, it was found that there was little difference in material properties indexes. According to the change trend of larch wood with density, the pith, juvenile wood, mature wood, and overmature wood were divided, which provided a reference value for the study of wood growth laws.

ИНДИВИДУАЛЬНАЯ ИЗМЕНЧИВОСТЬ МОРФОЛОГИЧЕСКИХ ПРИЗНАКОВ ЛИСТВЕННИЦЫ ПОЛЬСКОЙ В УСЛОВИЯХ ИНТРОДУКЦИИ

Polish larch trees are among the most valuable among forest species both in natural growing conditions and in the conditions of introduction. However, its taxonomic status is not fully resolved due to the similarity in morphological features with European and Siberian larch. We conducted a comparative analysis of these species of larch on the morphological features of cones and needles. The studies were carried out in the conditions of introduction in the center of the European part of Russia. We present the average value of the trait (XSR ± Sx) and the degree of its variation (V %). The reliability of the difference between the samples according to these characteristics was determined based on the calculation of the student's criterion t. As a result, we found that the Polish larch has smaller cones and significantly differs from the European and Siberian larch in all studied features (length of cones, width of cones, number of scales in cones, length of needles). These results indicate the isolation of the Polish larch, but this pattern can be expressed not only when referring to the Polish larch in the rank of an independent species – Larix polonica Racib., but also as a subspecies of European larch (Larix decidua var. polonica (Racib. ex Wóycicki) Ostenf. &amp; Syrach).