An experimental study and modeling of the behavior of wood during compression along the fibers was carried out. The nonlinear analytical dependence of the load on the strain was considered. Attention was focused on the post-peak stage of deformation in order to determine the load and displacement at which the transition to the stage of plastic deformation occurs. The work was aimed at substantiating the application of the energy criterion of brittle fracture as a criterion for the transition to the stage of plastic deformation. To achieve this goal, methods of mathematical modeling and analysis of test results were used. As an upshot, a simple and practical procedure was developed to predict the transition point to the above stage of plastic deformation. The simulation results were consistent with laboratory tests of samples and fragments of structures. The practical significance of this criterion lies in its possible use as an additional tool for analyzing the condition of some wooden structures. Energy criteria, including the one mentioned above, belong to fairly universal criteria. Accordingly, the research methodology can be adapted to analyze the behavior of, for example, composites under other types of loads in further studies.

The relevance of problems related to the fracturing of engineering materials and structures will not decrease over time. Fracture mechanics methods continue to be developed, which, combined with numerical methods of computer modeling, are implemented in software packages. However, this is only one facet of the complex of actual problems related to modeling and analyzing the behavior of brittle materials. No less important are the problems of developing not only numerical, but also new analytical models. In this paper, analytical models of only one class are considered, the distinguishing feature of which is that they describe the full load–strain curve using only one equation. However, the determination of model parameters requires tests for which the destruction of the test object is necessary, which may be unacceptable if controlled destruction is technically impossible or economically unreasonable. At the same time, in practice, it is possible to obtain values of stresses and strains caused by loads smaller than the peak load. Pre-peak loads can be used to predict strength using numerical methods, but it is desirable to have a suitable analytical model to extend the capabilities and to reduce the cost of applied research. Such a model was not found in the known literature, which motivated this work, which aims to modify the analytical model to predict strength and the full load–displacement (or stress–strain) curve using only pre-peak loading. This study is based on the analysis of known data and synthesis using mathematical modeling and fracture mechanics. The input data for the model do not include the particle size distribution and other physical and mechanical properties of the components of the material under study. These properties may remain unknown, but their influence is taken into account indirectly according to the “black box” methodology. Restrictions of the scope of the model are defined. The simulation results are consistent with experiments known from the literature.

The quality of planted forest crops depends significantly on the qualities of the planting stock. Numerous studies have been carried out to find clear seedling quality criteria and work out methods for their quantitative assessment to optimize the cultivation regime. Indicators of planting stock that are available for measurement under nursery conditions are needed to predict the success of forest crop establishment. This paper provides a review of the studies that applied different morphological criteria to evaluate coniferous planting stock quality and different determination methods. The suitability of planting stock quality indicators is determined by the effectiveness of predicting the outplanting survival rate (%) and growth. The key morphometric attributes of planting stock are the linear dimensions and biomass of whole seedlings and their individual organs: root collar diameter (RCD), seedling height (SH), dry mass of needles (NDM), stem (SBDM), roots (RDM), shoot/aboveground part of the seedling (SDM), seedling’s total dry matter (TDM), number of needles (NN). Effective indicators of seedling quality are morphometric indicators of roots: total length (TRL), volume (TRV), dry mass (RDM), number of first- (FOLR N), second- (SOLR N), and third-order (TOLR N) lateral roots, root surface area (TRS). TRL is a fairly reliable indicator of absorbent surface area. To minimize errors in the use of one or two traits, integrated seedling quality indices based on two or more indices have been developed. Widely used indices include: SQ = SH(cm)/RCD(mm); SDM/RDM ratio; Dickson quality index DQI = TDM/ ((SH / RCD) + (SDM / RDM)). RCD was the most suitable parameter to indicate seedling quality for many species due to its higher correlation level with the Dickson quality index. The SH index proved to be an effective indicator for analysis only when used together with RCD. When studying the formation of frost resistance, a number of morphological parameters are used: initiation of needle primordia, size of primordial shoots, cell volume, mitotic index (MI) of terminal primordia. Despite advances in testing planting stock quality and predicting field performance, not a single test is universally applicable for all woody plant species and environmental conditions. According to the target seedling concept, the application of morphometric criteria for assessing seedling quality in forest nurseries is a prerequisite for predicting outplanting success and maximizing the predictability of the outcomes of highproductivity forest crop planting. For citation: Robonen E.V., Chernobrovkina N.P., Egorova A.V., Zaitseva M.I., Nelaeva K.G. Morphometric Criteria for Assessing the Containerized Conifers Seedlings Quality. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 42–57. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-42-57

The quality of forest crops significantly depends on the characteristics of the planting stock. To obtain high-quality conifer seedlings, the process of container cultivation is used and optimized and a double-cropping mode is introduced. The aim of this study has been to conduct a comparative analysis of one-year-old containerized seedlings of Pinus sylvestris L. according to morphometric parameters under a double-cropping regime under short growing season conditions at high latitudes. The experiment has been carried out in a forest nursery in southern Karelia, Russia. The duration of the first rotation (1rot) has been 146 days, the second one (2rot) – 91 days, the control one (0rot) – 132 days. The following parameters of seedlings have been determined: seedling height (SH, cm), root length (cm), bud length (mm), root collar diameter (RCD, mm), tree dry mass (TDM, g), shoot dry mass (SDM, g), root dry mass (RDM, g) and needle dry mass. The integral quality indices have been assessed, such as: shoot : root dry mass ratio (SRR) = SDM/RDM, sturdiness quotient (SQ) = SH(cm)/RCD(mm) and Dickson Quality Index (DQI) = TDM/(SH + SRR). The lowest values of seedling dry mass have been revealed in the 2rot variant. For all variants, the difference between the mean SQ and DQI values has been statistically significant at the p < 0.05 level. SRR was the lowest in the 1rot seedlings. The high correlation coefficients between the TDM and RCD for all variants confirm the high significance of the latter index. The results indicate the need to adjust the time regime and use additional agricultural practices to obtain high-quality planting stock.

Free arginine (Arg) content was observed to multiply when the level of nitrogen (N) nutrition was high, and additional fertilization with boron (B) potentiated this effect. Owing to this feature, conifers can be suggested for use as bioproducers of Arg. Concentrations of Arg in relation to N and B fertilization needed to be better understood. The effect of soil fertilization with N and B on accumulation of these elements and free Arg in one-year-old needles of 16-year-old Scots pine (Pinus sylvestris L.) trees was determined in this study. Plantations were fertilized with doses of N from 0 to 1000 kg ha⁻¹ and B from 0 to 6 kg ha⁻¹. Fertilization with 3 kg ha⁻¹ B at N doses of 200–500 kg ha⁻¹ stimulated the accumulation of N in needles of up to 3.1–3.6% dry weight (DW). The level of Arg in needles increased from 74.7 to 175.9 μmol g⁻¹ DW at these levels of N and B.