Search Results (5)

In this work, we evaluated the silvicultural and ecological parameters of Populus bolleana Lauche trees growing in conditions of anthropogenic pollution, using the example of one of the largest megacities of the Donetsk ridge, the city of Donetsk. The objectives of this study included determining the level of anthropogenic load of the territory; conducting dendrological studies to assess morphometric and allometric parameters, age structure, and condition of P. bolleana stands under the influence of environmental factors; as well as completing biomechanical studies to assess and predict the mechanical stability of stands. A total of 1109 plants growing in areas with increased anthropogenic load and in the control areas were studied. The model territories of the study were located in the city of Donetsk on Fallen Communards Avenue (length of field routes: 2.6 km) and Ilyicha Avenue (length of field routes: 9.7 km). Control plantings grew on the territory of the Donetsk botanical garden and residential (dormitory) districts of the city. The age structure of P. bolleana plantations remained uniform throughout the city for 50–55 years due to the fact that the landscaping was under a single state program. In the steppe zone in the south of the East European Plain, with a high level of anthropogenic load and severe natural climatic factors, the critical age of P. bolleana (55 years) was determined. The condition of plantations and their morphometric indices correlate with the level of anthropogenic load of the city (H, Dbase, DBH). Under control conditions, the plants are in good condition with signs of weakening (2 points). Under conditions of increased anthropogenic load, the plants are in a severely weakened condition (3 points). A total of 25% of the plants in the sample are in critical condition (4–5 points). The main damages to the crowns and trunks of plants include core rot, mechanical damage to bark and tissues, the development of core rot through the affected skeletal branch, crown thinning, and drying. P. bolleana trees are valued for their crown area and ability to retain dust particles from the air. The analysis of experimentally obtained data on the crown area showed that in the initial phases of ontogenesis, the average deviation in the crown area of plants does not depend on the place of growth. Due to artificial narrowing and sanitary pruning of the crown, as well as skeletal branches dying along the busiest highways, the values do not exceed 22–23 m² on average, with an allometric coefficient of 0.35–0.37. When comparing this coefficient in the control areas, the crown area in areas with a high level of anthropogenic load is 36 ± 11% lower. For trees growing under the conditions of the anthropogenic load of an industrial city and having reached the critical age, mechanical resistance varied depending on the study area and load level. At sites with a high level of pollution of the territory, a significant decrease in indicators was revealed in comparison with the control (mcr—71%, EI—75%, RRB—43%). Having analyzed all the obtained data, we can conclude that, until the age of 50–55 years, P. bolleana retains good viability, mechanical resistance, and general allometric ratios, upon which the stability of the whole plant depends. Even with modern approaches and tendencies toward landscaping with exotic introductions, it is necessary to keep P. bolleana as the main species in dendrobanocenoses. Full article

About forty years after its first application, digital image correlation (DIC) has become an established method for measuring surface displacements and deformations of objects under stress. To date, DIC has been used in a variety of in vitro and in vivo studies to biomechanically characterise biological samples in order to reveal biomimetic principles. However, when surfaces of samples strongly deform or twist, they cannot be thoroughly traced. To overcome this challenge, different DIC setups have been developed to provide additional sensor perspectives and, thus, capture larger parts of an object’s surface. Herein, we discuss current solutions for this multi-perspective DIC, and we present our own approach to a 360° DIC system based on a single stereo-camera setup. Using this setup, we are able to characterise the desiccation-driven opening mechanism of two woody Hakea fruits over their entire surfaces. Both the breaking mechanism and the actuation of the two valves in predominantly dead plant material are models for smart materials. Based on these results, an evaluation of the setup for 360° DIC regarding its use in deducing biomimetic principles is given. Furthermore, we propose a way to improve and apply the method for future measurements. Full article

Cacti have a distinct adaptation to arid conditions with a massive water storing tissue surrounding a weak central woody cylinder. However, they have not been studied as extensively as other plants have been. Selenicereus undatus is a hemi-epiphytic root climber that attaches itself to supporting plants or rocks with adventitious roots. The anatomy and biomechanics of the adventitious roots were studied using light microscopy, X-ray tomography and pullout and uniaxial tensile tests. The central cylinder of the roots is highly lignified and is connected to the vascular system of the shoot in a peculiar way. Xylem elements of the root turn 90 degrees towards the base of the shoot and merge laterally and below the junction with those from the shoot. Tensile and pull-out tests showed that failure occurs either at the root or junction, with the fracture surface mainly comprising the area where xylem elements from the root merge with those from the shoot. However, damage to the cortical tissue was minimal, and the measured forces showed that adventitious roots have a high safety factor. Even a complete failure of the junction after pullout does not result in severe injury to the cortex, which could lead to water loss or the entry of pathogens. Full article

To maintain or adjust posture under the challenges of gravity and increased self-weight, or the effects of light, snow, and slope, plants have the ability to develop a special type of tissue called reaction tissue. The formation of reaction tissue is a result of plant evolution and adaptation. The identification and study of plant reaction tissue are of great significance for understanding the systematics and evolution of plants, the processing and utilization of plant-based materials, and the exploration of new biomimetic materials and biological templates. Trees’ reaction tissues have been studied for many years, and recently, many new findings regarding these tissues have been reported. However, reaction tissue requires further detailed exploration, particularly due to their complex and diverse nature. Moreover, the reaction tissues in gymnosperms, vines, herbs, etc., which display unique biomechanical behavior, have also garnered the attention of research. After summarizing the existing literature, this paper provides an outline of the reaction tissues in woody plants and non-woody plants, and lays emphasis on alternations in the cell wall structure of the xylem in softwood and hardwood. The purpose of this paper is to provide a reference for the further exploration and study of reaction tissues with great diversity. Full article

Self-supporting plants and climbers exhibit differences in their structural and biomechanical properties. We hypothesized that such fundamental differences originate at the level of the material properties. In this study, we compared three non-woody members of the Solanales exhibiting different growth habits: (1) a self-supporting plant (potato, Solanum tuberosum), (2) a trailing plant (sweet potato, Ipomoea batatas), and (3) a twining climber (morning glory, Ipomoea tricolor). The mechanical properties investigated by materials analyses were combined with structural, biochemical, and immunohistochemical analyses. Generally, the plants exhibited large morphological differences, but possessed relatively similar anatomy and cell wall composition. The cell walls were primarily composed of hemicelluloses (~60%), with α-cellulose and pectins constituting ~25% and 5–8%, respectively. Immunohistochemistry of specific cell wall components suggested only minor variation in the occurrence and localization between the species, although some differences in hemicellulose distribution were observed. According to tensile and flexural tests, potato stems were the stiffest by a significant amount and the morning glory stems were the most compliant and showed differences in two- and three-orders of magnitude; the differences between their effective Young’s (Elastic) modulus values (geometry-independent parameter), on the other hand, were substantially lower (at the same order of magnitude) and sometimes not even significantly different. Therefore, although variability exists in the internal anatomy and cell wall composition between the different species, the largest differences were seen in the morphology, which appears to be the primary determinant of biomechanical function. Although this does not exclude the possibility of different mechanisms in other plant groups, there is apparently less constraint to modifying stem morphology than anatomy and cell wall composition within the Solanales. Full article