The current state of heavy metal (HM) environmental pollution problems was considered in the review: the effects of HMs on the vital activity of plants and the functioning of their antioxidant system, including phenolic antioxidants. The latter performs an important function in the distribution and binding of metals, as well as HM detoxification in the plant organism. Much attention was focused on cadmium (Cd) ions as one of the most toxic elements for plants. The data on the accumulation of HMs, including Cd in the soil, the entry into plants, and the effect on their various physiological and biochemical processes (photosynthesis, respiration, transpiration, and water regime) were analyzed. Some aspects of HMs, including Cd, inactivation in plant tissues, and cell compartments, are considered, as well as the functioning of various metabolic pathways at the stage of the stress reaction of plant cells under the action of pollutants. The data on the effect of HMs on the antioxidant system of plants, the accumulation of low molecular weight phenolic bioantioxidants, and their role as ligand inactivators were summarized. The issues of polyphenol biosynthesis regulation under cadmium stress were considered. Understanding the physiological and biochemical role of low molecular antioxidants of phenolic nature under metal-induced stress is important in assessing the effect/aftereffect of Cd on various plant objects—the producers of these secondary metabolites are widely used for the health saving of the world’s population. This review reflects the latest achievements in the field of studying the influence of HMs, including Cd, on various physiological and biochemical processes of the plant organism and enriches our knowledge about the multifunctional role of polyphenols, as one of the most common secondary metabolites, in the formation of plant resistance and adaptation.

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Heavy Metals, Their Phytotoxicity, and the Role of Phenolic Antioxidants in Plant Stress Responses with Focus on Cadmium: Review

Spatial prediction of soil properties using random forest, k-nearest neighbors and cubist approaches in the foothills of the Ural Mountains, Russia

The correlation between the yield of Siberian spruce (Picea obovata Ledeb.) and Siberian fir (Abies sibirica Ledeb.) cones and radial wood increments was examined using long-term data (47 years) from direct observations. Broad-leaved coniferous woods of the Ufa Plateau (PreUral), which are located inside the Ufa River's water protection zone, make up the special polygon where the research was conducted. According to the experiments, there was no correlation with the yield of cones and the radial increment of wood, either positive or negative. Simultaneously, it was discovered that there is a rise in the radial increment of timber wood with an increase in the number of spruce and fir cones in the climatic circumstances of a particular year. The maximum growth of the plant's vegetative mass, in this case, the radial growth of the timber wood, is shown in the year with the highest cone output. Consequently, fir and spruce in this area have the effect of reversing reproductive effort.

https://www.e3s-conferences.org/articles/e3sconf/pdf/2023/27/e3sconf_agritechviii2023_07040.pdf

Reproductive effort assessment for woody plants using Siberian spruce and Siberian fir

The study examined the growth characteristics of the Siberian spruce (Picea obovata Ledeb.) under the canopy of coniferous forests in early ontogeny. We revealed that spruce undergrowth in adverse conditions is suppressed, is slow to grow and has xylorhizomes. The result is a significant difference in height, age and stage of ontogeny that affects the forest’s growth dynamics. The formation of xylorhizomes changes the relative dimensions of the above-ground part and the plant’s absolute height from 42 to 75%, depending on age. We identified two periods of growth intensity (slow and stable) and the critical age for spruce undergrowth to move from one stage of ontogeny to the next. If it does not make the transition, it will die. There are two strategies for developing spruce undergrowth: a “direct” path during rapid growth and a “waiting” path when the plants are suppressed. Such growth pathways in the pre-generative stage of the Siberian spruce’s ontogeny allow the undergrowth, even in a suppressed state, to survive in an adverse environment under the forest canopy.

Suppressed Undergrowth of Siberian Spruce (Picea obovata Ledeb.) in Early Ontogeny: One-Way Ticket or Survival Strategy?

Damage, Adaptations, and Strategies of Tree Species in Technogenesis Conditions: Structural and Functional Levels of Realization of Adaptive Potential

Forest-forming species of the Cis-Urals (pine, spruce, larch, oak, linden, birch) and soils in forest stands of these species were chosen as study objects. The content of heavy metals (HM) in leaves and needles of forest-forming species, as well as in soils, was analyzed. Different concentrations of HMs were revealed depending on the soil layer. It was shown that adaptations to HM pollution do not depend on whether trees belong to coniferous or deciduous species, which indicates different adaptive potentials of species in each specific case.

Technogenic Pollution of Soils with Heavy Metals and their Accumulation in Leaves and Needles of Forest-forming Species of the Cis-Urals

Restoring forests in areas where they once stood is an important step towards increasing carbon sequestration. However, reforestation requires an increase in current levels of seedling production in the tree nurseries. The purpose of this work was to study the effectiveness of preparations based on bacteria and humic substances (HSs) to stimulate the growth of tree seedlings in a nursery. Two selected strains of Pseudomonas and humic substances were used to treat pine and poplar plants. The treatment of seedlings was carried out during their transplantation and after it, and the effects of treatment on shoot elongation, shoot and root mass were evaluated. Treatments with both bacterial strains enhanced the growth of poplar and pine shoots and roots, which was explained by their ability to synthesize auxins. P. protegens DA1.2 proved to be more effective than P. sp. 4CH. The treatment of plants with humic substances increased the nitrogen balance index and the content of chlorophyll in the leaves of poplar seedlings, which can elevate carbon storage due to the higher rate of photosynthesis. In addition, the combination of humic substances with P. protegens DA1.2 increased shoot biomass accumulation in newly transplanted pine plants, which indicates the possibility of using this combination in plant transplantation. The increase in length and weight of shoots and roots serves as an indicator of the improvement in the quality of planting material, which is necessary for successful reforestation to increase capture of carbon dioxide.

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Microbial Preparations Combined with Humic Substances Improve the Quality of Tree Planting Material Needed for Reforestation to Increase Carbon Sequestration

Ruslan Urazgildin

Papers

Suppressed Undergrowth of Siberian Spruce (Picea obovata Ledeb.) in Early Ontogeny: One-Way Ticket or Survival Strategy?

Damage, Adaptations, and Strategies of Tree Species in Technogenesis Conditions: Structural and Functional Levels of Realization of Adaptive Potential

Technogenic Pollution of Soils with Heavy Metals and their Accumulation in Leaves and Needles of Forest-forming Species of the Cis-Urals

Damage, Adaptations, and Strategies of Tree Species in Technogenesis Conditions: Structural and Functional Levels of Realization of Adaptive Potential

Microbial Preparations Combined with Humic Substances Improve the Quality of Tree Planting Material Needed for Reforestation to Increase Carbon Sequestration