Influence of soil moisture level on metabolism of non-structural carbohydrates in Quercus robur leaves

The long-term increases in average temperature and intensification of droughts which characterise the current state of the Earth’s climate system have a negative impact on forest ecosystems and can lead to a decrease in their area and deterioration of the living conditions of their components. In the conditions of the Ukrainian Steppe an important environmental, antierosion, water-protective and soil-protective role belongs to the ravine forests. The most valuable component of the ravine forests is presented by natural populations of common oak (Quercus robur L.), which are able to tolerate the arid climate typical of the steppe region. But with global warming, the endurance of this species is changing. It is believed that a significant role in plant adaptation to drought and high temperatures may belong to non-structural carbohydrates. Therefore, it is important to study changes in the concentration of these substances in the leaves of this leading species under the action of adverse hydrothermal conditions. The article analyzes the content and dynamics of soluble sugars (glucose, fructose, sucrose) and starch in the leaves of Quercus robur L. under different forest growth conditions of the ravine forest (hygromesophilic (CL2–3), mesoxerophilic (CL1) and xerophilic (CL0)). The research was conducted in the forest in the Viyskove area (steppe zone of Ukraine) in the thalweg and at different levels of slope of southern exposure. Content of glucose, fructose, sugar and starch in Quercus robur leaves was determined. It was found that when exposed to high temperatures and increasing water stress during the vegetation period in xerophilic (CL0–1) and mesoxerophilic (CL1) forest growth conditions, the concentration of both glucose and sucrose in the leaves of Q. robur increases and it becomes much higher than in conditions of more optimal water supply. At the same time, the disaccharide content increases more significantly than that of monosaccharide. The greatest amount of these sugars is observed in the driest months (July, August), when conditions for providing plants with water are the most stressful. When water stress grows the increase in concentration of glucose and sucrose is correlated with reduction of starch content. It has been found that the concentration of fructose in Q. robur leaves in droughty conditions of growing was comparable to more favourable conditions of moisture. In September, there is a decline in the content of all forms of non-structural carbohydrates in the leaves of plants of all variants compared to the previous month, especially in conditions of adverse water supply. Therefore, forest growth conditions do not affect the nature of the dynamics of soluble sugars and starch in the leaves of Q. robur, although they change their quantitative indicators. Based on the protective function of sugars under the action of stressors on plants, we can assume that in conditions of significant lack of moisture in the soil their accumulation in the leaves in areas with mesoxerophilic and xerophilic hygrotopes plays an important role in increasing Q. robur drought resistance.

Распределение механических свойств древесины лиственных пород в годовых кольцах, выявленных методом сканирующего наноиндентирования

The paper presents the results of mechanical properties scanning by means of nanoindentation across the annual growth rings of deciduous trees wood, small-leaved lime (Tilia cordata) and common oak (Quercus robur) in particular. Significant variations in microhardness H and Young’s modulus E radial dependencies have been found for any of the studied species. Results can be useful 1) to amend the understanding the nature of macromechanical properties of various wood species and to reveal the details of their formation depending upon microstructural characteristics, 2) to optimize the technologies of growing, reinforcement and subsequent usage of the wood, 3) to develop new independent methods in dendrochronology and dendroclimatology

Preservation of Quercus Robur and Quercus Petraea Genetic Resources through In Vitro Culture

In this paper, the effect of various factors (clone, initial explant, sterilization method, and culture medium) on the in vitro multiplication of pedunculate and sessile oak species was tested. No influence of clone was found and a 44-83% survival rate was found for different types of explants, the best result being that of using mature acorns germinated in vitro. The most efficient sterilization method was: mercuric chloride 0.2 mg/l, ascorbic acid 1 mg/l, for 30 min., with or without antibiotic. The best results were obtained with GD medium complemented with 0.5 mg/l BAP and 0.1 mg/l IBA, which allowed obtaining of a high rooting percentage. The regenerated plants were transferred in vivo, in a climate controlled greenhouse.

SURFACE IRREGULARITIES OF OAK WOOD AFTER TRANSVERSAL CUTTING WITH A CIRCULAR SAW

This paper deals with the effect of saw blade type (24, 40 and 60 teeth) and sawn distance on the primary profile (Pz) of tranvesre surface of European oak (Quercus robur L.) after transversal cutting. Transversal cutting was provided at constant cutting speed vc = 62 m.s-1and with manual feeding using circular saw blade. An additional parameter was to determine the maximum sawn distance for each type of saw blade up to the point where the saw blade overheated, as well as the beginning of the blackening of the wood surface. The highest values of the primary profile (Pz) were achieved with a saw blade with 24 teeth, lower values were measured on wood cut with a 40 tooth blade and the lowest values after cutting with a 60 tooth blade. As the saw distance increased, there was no rapid and steep increase in the primary profile values, but these values gradually increased slightly, probably due to the gradual blunting of the tool.

Request (4) and Proposal (28): to conserve the name Molinio arundinaceae-Quercetum roboris Neuhäusl et Neuhäuslová-Novotná 1967

We propose (i) to select Quercus robur as the name-giving taxon of the associations Molinio arundinaceae-QuercetumSamek 1962 and Molinio arundinaceae-QuercetumNeuhäusl et Neuhäuslová-Novotná 1967 and (ii) to conserve the younger name Molinio arundinaceae-Quercetum roborisNeuhäusl et Neuhäuslová-Novotná 1967, representing hygrophytic Central European acidophilous oak forests (Quercion roboris alliance). (28) Molinio arundinaceae-QuercetumNeuhäusl et Neuhäuslová-Novotná 1967: 17–23, table 2. Typus: Neuhäusl and Neuhäuslová-Novotná (1967), table 2, rel. 11 (lectotypus; Pallas 1996: 51). (H) Molinio arundinaceae-QuercetumSamek 1962: 134–135, table V on p. 156–160. Typus: Samek (1962), Table V, rel. 28 (lectotypus; Moravec 1998: 33). Taxonomic reference: Marhold et al. (1998). Abbreviations: ICPN = International Code of Phytosociological Nomenclature.

Two new species of Diaporthe (Diaporthaceae, Diaporthales) associated with tree cankers in the Netherlands

Diaporthe (Diaporthaceae, Diaporthales) is a common fungal genus inhabiting plant tissues as endophytes, pathogens and saprobes. Some species are reported from tree branches associated with canker diseases. In the present study, Diaporthe samples were collected from Alnus glutinosa, Fraxinus excelsior and Quercus robur in Utrecht, the Netherlands. They were identified to species based on a polyphasic approach including morphology, pure culture characters, and phylogenetic analyses of a combined matrix of partial ITS, cal, his3, tef1 and tub2 gene regions. As a result, four species (viz. Diaporthe pseudoalnea sp. nov. from Alnus glutinosa, Diaporthe silvicola sp. nov. from Fraxinus excelsior, D. foeniculacea and D. rudis from Quercus robur) were revealed from tree branches in the Netherlands. Diaporthe pseudoalnea differs from D. eres (syn. D. alnea) by its longer conidiophores. Diaporthe silvicola is distinguished from D. fraxinicola and D. fraxini-angustifoliae by larger alpha conidia.

Norway maple (Acer platanoides) and pedunculate oak (Quercus robur) demonstrate different patterns of genetic variation within and among populations on the eastern border of distribution ranges

Norway maple (Acer platanoides L.) is a key species of broadleaved forests whose population genetics is poorly studied using modern genetic tools. We used ISSR analysis to explore genetic diversity and differentiation among 10 Russian populations on the eastern margin of the species range of distribution, and to compare the revealed patterns with the results of our population genetic studies of pedunculate oak (Quercus robur L.). In the first set comparatively high heterozygosity and allelic diversity were found (expected heterozygosity H_E = 0.160 ± 0.033, number of alleles n_a = 1.440 ± 0.080, effective number of alleles n_e = 1.271 ± 0.062) in comparison with strongly fragmented and geographically isolated small maple stands of the second set (H_E = 0.083 ± 0.011, n_a = 1.281 ± 0.031, n_e = 1.136 ± 0.019). A relatively high genetic differentiation among populations was detected (the proportion of the inter-population component of total genetic variation, G_ST = 0.558 ± 0.038). In the Cis-Urals, local groups of populations that are confined to the northern, middle and southern parts of the Urals were identified. On the contrary, the current significant fragmentation of the pedunculate oak distribution area in the same study area did not lead to any noticeable genetic differentiation among the majority of populations, the values of the population genetic diversity were very similar in different parts of the Southern Urals.

Appreciation of tolerance at the impact of thermal stress on photosystem ii activity in the leaves of pedunculate oak (Quercus robur L.) trees of different ecological origin

Extreme weather events with high temperatures and strong sunlight have increased alarmingly in the last few decades, considerable affecting plant photosynthesis. In this study, the impact of thermal stress on photosystem II activity in the leaves of pedunculate oak trees (Quercus robur L.) of different ecological origin was assessed. Four days after the thermal shock application with a temperature of 50°C during 20, 40, 60 minutes, the processes of recovery on photosystem II activity in the leaves of the oak trees in the investigated provenances took place with different speed and fullness. The recovery of the functional state of photosystem II in the leaves of the trees showed that in the environmental conditions of the ,,Plaiul Fagului” reservation territory an advanced thermotolerance to the thermal stress action was specifi c for the origin from the north of the country (Edinet). The leaves of the trees of local and southern origin showed a low resistance to the thermal stress action. The advanced adaptation capacity, the high growth rate of the trees from the northern provenance suggest that the acorn harvested from the oaks of northern origin can be used for the works of extension of the afforestation areas in the central area of the Republic of Moldova.

Experience In Creating Artificial Forest Plants In The Territory Of Belgorod Region

The experience of creating artificial forest plantations on the territory of the Belgorod region within the framework of the “Green Capital” project is considered. As part of the project, it was envisaged to create more than 100 thousand hectares of forest plantations on chalk slopes and erosion-hazardous areas of the region for 2010 - 2020, that is, bringing the forest cover of the region to 15% - the optimal value for the region. For the period 2010 - 2020 forest plantations were laid on the territory of more than 87.7 thousand hectares. For afforestation in the region, species are recommended that provide sustainable, durable and ecologically capacious afforestation: as the main species on chernozem soils: Quercus robur L., Q. rubra, Fraxinus excilsior L., Larix sibirica Ledeb .; on sandy soils - Pinus sylvestris L. Reforestation has been carried out since 2010 on the territory of 22 districts of the region. In 2016-2020 more than 6 thousand hectares of oak forests were created. As a result, the species Q. robur occupies an area of 22.2% of the area of artificial plantations; P. silvestris accounts for 13.2% of the area of artificial plantations in the oblast. Next in terms of planting volumes are such crops as A. hippocastanum, R. pseudoacacia and F. excélsior - 12.1%, 24.7% and 14.4%, respectively. The share of fruit crops, as well as B. pendula, A. platanoide, A. campestre, and U. laevis, is 11.7%.