Pedunculate Oak Seedlings Research Articles

Effect of sowing density on performance and biometric features of pedunculate oak

Sowing density is one of the most important factors influencing seedling quality. In forest nurseries, to ensure full seeding, it is recommended to obtain approximately 200 seedlings from 1 m2 (ZHL 2012). The aim of the study was to assess the effect of sowing density on sowing efficiency and the morphological features of pedunculate oak seedlings. Acorns were sown directly by broadcast seeding on 20 test plots, each 4 m in length, in four replications. The following variants were used:- 250acorns capable of germination totaling 341 acorns per 1 linear meter (0.9 m2);- 300 acorns capable of germination totaling 410 acorns per 1 linear meter (0.9 m2);- 350 acorns capable of germination totaling 478 acorns per 1 linear meter (0.9 m2);- 400 acorns capable of germination totaling 546 acorns per 1 linear meter (0.9 m2);- 450 acorns capable of germination totaling 614 acorns per 1 linear meter (0.9 m2). At the end of the growing season, seedlings were counted per 1 m (0.9 m2) in the central part of each plot. Sowing efficiency was determined as a percentage of seedling yield from the sown seeds. For laboratory analysis, 30 seedlings from each plot (600 in total) were collected. Based on biometric features like shoot height, root collar diameter, and dry weights of shoots, roots, and leaves, quality indicators such as the sturdiness quotient (SQ) and the Dickson quality index (DQI) were calculated. Sowing efficiency at the end of the vegetation season ranged between 39.68% and 50.12% and was not statistically significant. The research revealed that sowing density influenced seedling biometric characteristics. Pearson’s correlation coefficients showed significant negative correlations between the number of seedlings obtained in an experimental plot and the dry weight of the root, number and dry mass of leaves, as well as the DQI. The seedlings from all sowing variants complied with the binding Polish standard, outlined in the Regulation of the Minister for the Environment of 18 February 2004 (Ministerstwo Środowiska 2004) by over 96%. Keywords: seeding density, sowing rate, seedling quality, sowing performance, sturdiness quotient (SQ), Dickson quality index (DQI), Quercus robur L.

Study of the Effects of Polypropylene Tree Shelters and Hydrophilic Polymers on Growth, Survival, Health and Physiological Condition of Pedunculate Oak Seedlings ( L.)

This paper presents the results of eight years of scientific research on the effect of polypropylene shelters (Tully tubes) and hydrophilic polymers on growth, survival, health and physiological condition of pedunculate oak seedlings (Quercus robur L.). The experiment was established in 2014 on relative forest soil, on partially forested land in subcompartment 35a, forest management unit Kragujna, which is managed by the Forest Administration Vinkovci, Forest Office Županja. In the autumn of 2014, one-year-old bare-rooted pedunculate oak seedlings were planted as a randomized block design experiment - four blocks with four repetitions. Four types of planting were tested: seedlings without a polypropylene shelter, without the addition of Zeba hydrophilic polymer granules (S variant), seedlings without a polypropylene shelter, with the addition of Zeba hydrophilic polymer granules (SP variant), seedlings with a polypropylene shelter, without the addition of Zeba hydrophilic polymer granules (SS variant), and seedlings with a polypropylene shelter, with the addition of Zeba hydrophilic polymer granules (SSP variant). The experiment was established as a result of considering the long-term problem of difficulties in natural regeneration. Disturbances in natural regeneration are certainly caused by increasing climate changes (floods, long-term droughts, storms, hailstorms, etc.) and other unfavourable biotic and abiotic factors that cause a significant reduction in quantities and/or an almost complete absence of pedunculate oak acorn yield. Due to the aforementioned circumstances, in the very near future we will be forced to resort more often to different forms of artificial forest regeneration, such as regeneration by planting sheltered seedlings that are less exposed to risks and challenges during survival, and which have greater competitiveness in relation to other vegetation on the regeneration surface (higher growth). Nowadays, this method of regeneration is used mostly for filling in places where, for various reasons, natural regeneration has been unsuccessful on several occasions and over a long period of time, and/or where there are great difficulties in carrying out natural regeneration (floods, areas damaged by fires, game damages and competition of weeds). This paper presents the results of scientific research after five periodic measurements, i.e. after the first, second, fifth, sixth and eighth growing season. The results show that even after the eighth growing season, seedlings protected with a polypropylene shelter have greater survival rate and greater height growth than unprotected seedlings. The highest survival rate was found in seedlings protected with a polypropylene shelter, with the addition of Zeba hydrophilic polymer of 82.14% (SSP variant), while unprotected seedlings with the addition of Zeba hydrophilic polymer (SP variant) had the lowest survival rate of 62.63%. The highest growth was recorded on seedlings protected with a polypropylene shelter, with the addition of Zeba hydrophilic polymer (SSP variant) amounting to 202.75 cm, while on average the smallest seedlings were those without polypropylene shelter protection and without the addition of Zeba hydrophilic polymer (S variant), amounting to 129.02 cm.

Effect of Changing Substrate Density and Water Application Method on Substrate Physical Properties and Container-Grown Seedling Growth

The quality of container-grown seedlings is influenced by the air and water properties of the substrate. These properties are closely tied to the amount and frequency of water supplied through sprinkler systems in nurseries, as well as the density of the substrate in the container cells. Throughout the entire growing season, this study examined how various parameters of Scots pine, Norway spruce, European beech, and pedunculate oak seedlings cultivated in HIKO V120SS and V265 containers were affected by two factors. Firstly, the study analyzed the impact of increased substrate density when filling the containers. Secondly, it explored the precise dosing of water applied by the sprinkler system, which was determined based on substrate sensors and meteorological conditions surrounding the seedlings. The results revealed that increased substrate compaction led to a long-term reduction in air capacity and an increase in water capacity within pine, spruce, and beech containers. However, oak seedlings were not affected by the increased substrate density. Additionally, the higher density of the compacted substrate positively influenced the growth parameters of pine seedlings but did not affect the other species. As a result, the current substrate compaction level used in the nursery where the measurements were taken appears to be optimal for spruce, beech, and oak seedlings. Furthermore, precise control over the amount of water applied during irrigation allowed for a reduction in water consumption by about 8%. This control also resulted in improved seedling sturdiness quotient and a more developed root system in the case of pine seedlings. However, no significant differences were observed for the other species.

Resistance Inducers for the Protection of Pedunculate Oak (Quercus robur L.) Seedlings against Powdery Mildew Erysiphe alphitoides.

Oak powdery mildew caused by Erysiphe alphitoides (Griffon and Maubl.; U. Braun & S. Takam.) is a common disease in European forests. One of the most susceptible species is the pedunculate oak (Quercus robur L.). Presently, a few methods are available to control powdery mildew, e.g., the use of fungicides (e.g., based on citric acid), antagonistic fungi or bacteria, chemical treatments (e.g., sulphur, potassium bicarbonate) or genetic resistance. In our study, we aimed to check the effects of using chitosan derivatives and novel active substances inducing the plants' natural resistance: benzodiathiadiazole (both in neutral and salt form). 84 pedunculate oak seedlings were subjected to the experiment in three treatment variants (plus positive and negative controls). The plants were treated with active substances and inoculated with E. alphitoides. Although the powdery mildew symptoms appeared in all variants, they were manifested mainly by the mycelium in the form of small spots. The experiment indicated that the highest limitation of powdery mildew mycelium was achieved by applying N-methyl-N-methoxyamide-7-carboxybenzo(1,2,3)thiadiazole (BTHWA). The application of BTHWA reduced disease development by 88.9% when compared to the effects of the other variants.

ВЛИЯНИЕ НАНОЧАСТИЦ ЖЕЛЕЗА НА РОСТ СЕЯНЦЕВ СОСНЫ ОБЫКНОВЕННОЙ (PINUS SYLVESTRIS L.) И ДУБА ЧЕРЕШЧАТОГО (QUERCUS ROBUR L.)

The paper presents the results of a study of the effect of iron nanoparticles on the development of Scots pine ( Pinus sylvestris L.) and English oak ( Quercus robur L.) seedlings growing in the South Cis-Ural zone. It has been established that the morphobiological response of seedlings to the action of Fe nanoparticles has a species specificity. In pine seedlings, the presence of Fe nanoparticles at a concentration of 100 mmol / l had a toxic effect on the growth of Scots pine seedlings. The concentration of Fe nanoparticles 25 and 6.25 mmol / l stimulated the growth of Scots pine seedlings. With a nanoparticle content of 25 mmol / l, an increase in the length of the main root by 22.5 mm (23.1%). The number of adventitious roots in the experimental group, in comparison with the control, increased by 1.5%, the length of adventitious roots - by 10.8 mm (14.4%). Found that the seedlings of pedunculate oak are more resistant to the toxic effects of iron nanoforms. Morphometric parameters of seedlings of pedunculate oak in the experimental, as well as at a concentration of 100 mmol / l differed from those in the control group insignificantly, within 1%.

Evaluation of the “Pogoreloe” natural protected area after a decade

As a result of the evaluation of the protected natural area „Pogoreloe” after a decade there have been major changes. It was established that the installation of the reservatogenic protection regime and the development of the project had major changes in the composition and structure of the seedling and grass cover. This situation has both positive and negative consequences. The positive thing is that the regeneration of pedunculate oak has started. A lot of pedunculate oak seedlings have appeared in the protected area, which gives the possibility to grow a new generation of oaks that in the future could replace the secular oaks that are old. For this, it is recommended to carry out the works of eliminating the elm and maple seedling, which in many areas shades the pedunculate oak seedling. As a result of the appearance of this brood, the protected natural area „Pogoreloe” was transformed from a penetrable to impenetrable state. Based on the situation created, it is recommended to remove the elm and maole seedlings where the pedunculate oak seedling is shaded. It is necessary to thin the thickets of elm and maple, so that the young of these species become less in number in order to have a penetrable state of the protected natural area „Pogoreloe”.

The influence of powdery mildew on chlorophyll a fluorescence and stomatal characteristics of pedunculate oak (Quercus robur L.)

Oak powdery mildew (Erysiphe alphitoides (Griffon and Maubl.) U. Braun and S. Takam.)) is one of the most common foliar pathogenic organism of oaks, exploiting harmful effects, particularly on young seedlings. To assess and evaluate these negative effects, an experiment was conducted under semi-controlled conditions with 20 one-year-old seedlings of Quercus robur L. infected with E. alphitoides, half of them showing 50% of leaf coverage by epiphytic mycelia and the other half a coverage of 75%. The results of the present study have shown that all observed parameters of chlorophyll a fluorescence transient were highly effective in the detection of severe biotic stress. Moreover, the studied parameters of slow fluorescence kinetics were also considerably influenced, with the coefficient of non-photochemical fluorescence quenching and the Stem-Volmer type non-photochemical fluorescence quenching parameters showing the fastest responses. In case of leaf stomatal traits, the decrease of stomata guard cell width coupled with the increase of stomatal density was observed as the protective mechanism of Q. robur against the stressor. The overall results showed the adverse effects of powdery mildew infection on the photosynthesis of pedunculate oak seedlings, which progressed in time and depended on the severity of the infection. The importance of the results of the present study lays in evaluation and monitoring of the effects of powdery mildew development on the photosynthetic apparatus of one-year-old Q. robur seedlings, which is the most vulnerable stage for the infection by the mentioned pathogen.

EMPIRICAL USE OF THREE OAK SPECIES IN AFFORESTATION: LESSONS FROM SOWING AND TRANSPLANTING EXPERIMENTS

The effects of different factors on the growth in height and diameter of oak saplings in comparative cultures were estimated: progeny from autumn and spring sowing of acorns (1); growing conditions of pedunculate oak (Quercus robur L.) mother plants (2); the initial planting density of sessile oak (Q. petraea Liebl.) (3); natural lightening level of downy oak (Q. pubescens Willd.) mother plants (4). The pedunculate oak seedlings obtained after spring sowing were characterized by faster growth compared with those obtained from the autumn sowing. The lower growth rate observed in seedlings sown in autumn was due to the prolonged frosty weather during winter, which led to a decrease in acorn viability and progeny vigour. Due to the higher genetic diversity of the progeny obtained from the free-pollinated pedunculate oaks, it is possible that their growth was more intense and stable in comparison to those of saplings obtained from the acorns of isolated trees. The planting under the forest canopy had a clear influence on the growth in height of saplings. At low density levels (1.0 x 1.0 m), the sessile oak saplings benefited from larger availability of soil nutrients and displayed the highest growth, contrasting with those planted at high density (0.5 x 0.5 m). The deep and moderate shading caused a substantial reduction in the growth of downy oak saplings. Therefore, when planting, it is recommended to avoid using fast-growing species, which, due to asymmetric competition, could drastically reduce the growth in height of the downy oak saplings. Prolonged regeneration of the pruned root system following the transplantation process of sessile and downy oak seedlings determined their very slow growth in the first years of life.

Quercus robur as a Potential Cd Phytostabilizator

Pedunculate oak (Quercus robur L.) is one of the most important forest tree species in Europe, from both economic and ecological perspectives. Several studies indicate the possibility of using different species of the genus Quercus for afforestation of lands affected by industry, including trace-element polluted areas. The main objective of this research was to determine the Cd accumulation patterns of pedunculate oak seedlings subjected to various Cd treatments. Differences in Cd accumulation ability, mineral nutrients concentrations and observed damage upon Cd treatment of plants derived from different regions of origin are discussed. Obtained results suggest the possible use of pedunculate oak in cadmium phytostabilization.

Antioxidative system response of pedunculate oak (Quercus robur L.) seedlings to Cd exposure

The use of pedunculate oak (Quercus robur L.), along with other tree species, for the afforestation of heavy metal contaminated lands is an attractive prospect. Little, however, is known of Q. robur tolerance and its antioxidative system response to heavy metal exposure. The main objective of the study was to determine the cadmium-induced changes in antioxidative system of pedunculate oak in an attempt to identify molecular mechanisms underlying Cd tolerance. This may be of great importance in respect of using Q. robur for phytoremediation purposes. As the response of the antioxidative system to heavy metal contamination can vary within species, the research was conducted on oak seedlings from two different regions of origin. Differences in antioxidative system response of seedlings derived from tested regions of origin were noticed both at the transcript and enzyme activity levels. The obtained results indicate that ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) play a first barrier role in oak seedlings response to the oxidative stress caused by Cd exposure. Catalase (CAT; EC 1.11.1.6) is involved in reducing the negative effects of prolonged Cd treatment.

The Effects of Copper and Silver Nanoparticles on Container-Grown Scots Pine (Pinus sylvestris L.) and Pedunculate Oak (Quercus robur L.) Seedlings

Metal nanoparticles (NPs) are finding ever-wider applications in plant production (agricultural and forestry-related) as fertilisers, pesticides and growth stimulators. This makes it essential to examine their impact on a variety of plants, including trees. In the study detailed here, we investigated the effects of nanoparticles of silver and copper (i.e., AgNPs and CuNPs) on growth, and chlorophyll fluorescence, in the seedlings of Scots pine and pedunculate oak. We also compared the ultrastructure of needles, leaves, shoots and roots of treated and untreated plants, under transmission electron microscopy. Seedlings were grown in containers in a peat substrate, prior to the foliar application of NPs four times in the course of the growing season, at the four concentrations of 0, 5, 25 and 50 ppm. We were able to detect species-specific activity of the two types of NP. Among seedling pines, the impact of both types of NP at the concentrations supplied limited growth slightly. In contrast, no such effect was observed for the oaks grown in the trial. Equally, it was not possible to find ultrastructural changes in stems and roots associated with the applications of NPs. Cell organelles apparently sensitive to the action of both NPs (albeit only at the highest applied concentration of 50 ppm) were chloroplasts. The CuNP-treated oaks contained large plastoglobules, whereas those dosed with AgNP contained large starch granules. The NP-treated pines likewise exhibited large numbers of plastoglobules, while the chloroplasts of NP-treated plants in general presented shapes that changed from lenticular to round. In addition, large osmophilic globules were present in the cytoplasm. Reference to maximum quantum yields from photosystem II (Fv/Fm)—on the basis of chlorophyll a fluorescence measurements—revealed a slight debilitation of oak seedlings following the application of both kinds of NP at higher concentrations. In contrast, in pines, this variable revealed no influence of AgNPs, as well as a favourable effect due to the CuNPs applied at a concentration of 5 ppm. Our research also showed that any toxic impact on pine or oak seedlings due to the NPs was limited and only present with higher concentrations.

Agricultural techniques for cultivation of ball-rooted pedunculate oak seedlings based on the use of microbial preparations

Agricultural techniques for cultivation of ball-rooted pedunculate oak seedlings based on the use of microbial preparations

Micro-Food Web Structure Shapes Rhizosphere Microbial Communities and Growth in Oak

The multitrophic interactions in the rhizosphere impose significant impacts on microbial community structure and function, affecting nutrient mineralisation and consequently plant performance. However, particularly for long-lived plants such as forest trees, the mechanisms by which trophic structure of the micro-food web governs rhizosphere microorganisms are still poorly understood. This study addresses the role of nematodes, as a major component of the soil micro-food web, in influencing the microbial abundance and community structure as well as tree growth. In a greenhouse experiment with Pedunculate Oak seedlings were grown in soil, where the nematode trophic structure was manipulated by altering the proportion of functional groups (i.e., bacterial, fungal, and plant feeders) in a full factorial design. The influence on the rhizosphere microbial community, the ectomycorrhizal symbiont Piloderma croceum, and oak growth, was assessed. Soil phospholipid fatty acids were employed to determine changes in the microbial communities. Increased density of singular nematode functional groups showed minor impact by increasing the biomass of single microbial groups (e.g., plant feeders that of Gram-negative bacteria), except fungal feeders, which resulted in a decline of all microorganisms in the soil. In contrast, inoculation of two or three nematode groups promoted microbial biomass and altered the community structure in favour of bacteria, thereby counteracting negative impact of single groups. These findings highlight that the collective action of trophic groups in the soil micro-food web can result in microbial community changes promoting the fitness of the tree, thereby alleviating the negative effects of individual functional groups.

Effects of Mineral Soil and Forest Floor on the Regeneration of Pedunculate Oak, Beech and Red Oak

Early regeneration is a critical life stage that affects the future species composition of forests. Knowledge about regeneration success under different environmental conditions allows better understanding of forest dynamics. We studied the effects of seedbed conditions on the establishment and performance of seedlings of pedunculate oak, beech and red oak. In 50 plots of a tree-diversity oriented research platform in mature forests in northern Belgium (TREEWEB), we installed a field experiment with three treatments (potting soil, mineral soil, mineral soil + forest floor), in which we sowed seeds of each species. We monitored early establishment and survival, height, root and shoot biomass of the seedlings after two growing seasons. Mineral soil negatively affected seedling establishment and performance relative to the potting soil. The negative soil effects did not vary with measured abiotic soil properties. In general, the forest floor did not deteriorate or mitigate the soil effects, and only for root biomass did the forest floor partly compensate the negative soil effects. Forest floor effects did not vary with the measured forest floor properties. In the studied forests, creating bare soil was not enough to promote regeneration; improving soil properties might be important for the success of natural regeneration.

Вплив нітропрусиду натрію на ріст сіянців дуба звичайного та ураження борошнистою росою їх листкової поверхні

Вплив нітропрусиду натрію на ріст сіянців дуба звичайного та ураження борошнистою росою їх листкової поверхні

Influence of nitrogen fertilisation on biometric features of two-year-old seedlings of pedunculate oak subjected for root pruning

Abstract Pruning is one of the important cultural treatments that have potential to influence hardwood seedling morphology. The aim of the study was to compare the growth of pedunculate oak seedlings, performed pruning roots, in the second growing season, fertilised full and reduced dose of nitrogen. A total of 24 experimental plots, each with an the area of 0.04 ha, were designated. The roots pruning were made at the end of February 2014 using root pruning machine EGEDAL. The fertilisation, for all seedlings, was performed using ammonium nitrate in an amount of 25 kg ha−1 of nitrogen. The second fertilisation was performed only for variants 2 and 4. For these variants, urea was used in an amount of 25 kg ha−1. At the end of the growing season, the root collar diameter and the height of seedlings were measured. A dose of nitrogen affects the height of pruned seedlings. The effect of the full dose of nitrogen on the height of the pruned seedlings was a statistically significant (p ≤ 0.05). There was no statistical difference in the height of the seedlings without pruning, fertilised with different dose of nitrogen. Analysis of root collar diameter showed the significant differences between the variants. The Tukey test, at the significance level of p ≤ 0.05, showed a significant impact on the root collar diameter of pruned seedlings but no proven effect of nitrogen fertilisation. To conclude, we found that it is reasonable to reduce the doses of nitrogen fertilisation to half of recommended amount (25 kg ha−1) if the root system is not pruned during the second growth year. Seedlings that has received pruning should be fertilised using the recommended doses of nitrogen.

FORMING OF ROOTAGES OF PEDUNCULATE OAK PLANTS IN FOREST GULTURES USING VARIOUS METHODS OF FOREST RENEWAL IN STATE ENTERPRISE "SMILA FORESTRY"

Pedunculate Oak is the type of arboreal plants that in natural conditions have a long tap-root and widely ramified rootage. It allows it to grow both in dry and moist environments. A structure and development of arboreal plants have been investigated by the known scientists in forestry, in particular Soldatov A. G., Rahteenko I. N., Pogrebniak P. S., Pohiton P. P., Kalinin M. I., and Guz N. I. In order to research character and tendencies of height and development of rootages of Pedunculate Oak in the cultures of this arboreal type of plants using different methods of proceeding in the forest we conducted excavation of chums of this arboreal type in age from one to three years on a depth up to 1.5 m on the areas of forest cultures, that is created by sowing of acorns, landing of bare-rooted seedlings and container plants. For comparison of development of rootages of one-year Pedunculate Oak plants, that were grown according to traditional technology with root system in the nursery of Volodimirovka and one-year seedlings of Pedunculate Oak, that grew in forest cultures of the sown acorns, and also container seedlings, that were grown in the nursery of Bydianka of Smila forestry of the Tcherkasy regional department of forest and hanting we defined mass of rootages of arboreal plants in an air-dry state, that presented accordingly 2.7±0.3, 2.8±0.3 and 10.0±1.8 g. In such conditions the three-year plants of Pedunculate Oak had middle length of rootages – 124.2±12.9 cm. Rootages of three-years plants of Pedunculate Oak in forest cultures on the areas of forest renewal with the use of container planting stock comparatively with the rootages of the same age of Pedunculate Oak plants in the forest cultures that were created by bare-rooted seedlings is more fibrous and after the depth of their distribution on average presented a 126.3±21.8 cm against a 68.3±18.2 cm, at the same time, the amount of arboreal plants with the formed mainroot a container plants did not exceed their half. Digging at the root of two-year oak that grew from acorns, we found existing vertical root system with an average depth of penetration taproot 72.1± 9.2 cm, in which horizontal roots were mostly roots of the first order and second minor branching roots and third orders. In reforested areas created by planting seedlings with bare root system and grown in containers we observed well-developed fibrous root systems that were formed in the fertile layer of soil. At the same time, rootages of two-year arboreal plants of oak ordinary, that were grown in containers, comparatively with the rootages of two-year plants of this arboreal kind, planted with bare roots, were substantially more powerful. Middle length of rootages of Pedunculate Oak plants in two-year forest cultures created according to traditional technology, we fixed a 46.2±5.2 cm with indexes, and by a container planting stock are 76.2±7.8 cm. In the rootages of plants of oak ordinary on areas renewal of the forest by a planting-stock bare-rooted and grown in containers the roots of near to horizontal directions of the first, second and third orders and bulk of chums prevailed was in the epiphases of soil on half meter depth. Thus, the results of digging out of rootages of three-year plants of Pedunculate Oak in the forest cultures created by sowing of acorns showed the middle depth of rootages, and their medium-altitude above-ground part presented a 117.6±12.1 cm, that testifies to forming Pedunculate Oak of such cored rootage. Researches of three-year rootages of Pedunculate Oak in the forest cultures created according to traditional technology and with the use of container planting stock showed that part of their individuals with a dominant mainroot did not exceed halves of their amount, and the tendency of forming of rootages that was educed by the authors on second year of their life, continued to be kept.

Effects of light availability on morphology, growth and biomass allocation of Fagus sylvatica and Quercus robur seedlings

The survival, morphological, and growth responses of European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) seedlings to different light intensities, from full sunlight to heavy shade, were studied over two growing seasons in a shadehouse experiment. Although shade treatments significantly affected seedling growth, they did not influence seedling survival. Both growth and biomass increased as light intensity increased. Diameter growth of oak seedlings was higher than that of beech. Beech and oak seedlings showed typical acclimation to shade, including greater specific leaf area and height to diameter ratios, and lower leaf thickness and root:shoot ratios with increasing shade. Beech seedlings exhibited greater specific leaf area, and lower leaf thickness and root:shoot ratios than oak seedlings. In spite of the greater growth at full sunlight, the results from this study suggest that beech and oak seedlings would have high survival rates and would acclimate well if underplanted below overstories that reduce the available light to as low as 28% of full light.

Obnova lesa pod výstavky dubu letního (Quercus robur L.)

Work objective was to establish reasons to the impaired vitality of woody and herbaceous vegetation growing under standards of pedunculate oak (Quercus robur L.). The paper analyzes the influence of insolation, root competition, soil moisture content and chemical composition of soil on the growth of pedunculate oak seedlings under standards. The analyses included three standards of pedunculate oak aged over 150 years, growing at an altitude of 160 m a.s.l. Controls were plots occurring at a distance of 20 m from the standards. Conclusions following out from the analyses are as follows: The number of seedlings emerged under the standards was lower than the number of seedlings emerged in the open area. Shoot height as well as root collar diameter of seedlings under the standards were lower than in the control seedlings. Total cover of herbaceous layer and height of herbs under the standards were lower than in the open area. The impaired vitality of woody and herbaceous vegetation resulted from a great amount of the fine roots of pedunculate oak standards, withdrawing water up to the wilting point. The amount of photosynthetic active radiation (PAR) under the standards was sufficient for the growth of plants.

Cause–effect relationship among morphological adaptations, growth, and gas exchange response of pedunculate oak seedlings to waterlogging

In response to waterlogging, pedunculate oak is known to develop adventitious roots and hypertrophied lenticels. However, to date, a link between these adaptations and the ability to maintain net CO2 assimilation rates and growth has not been demonstrated. The aim of this study was to explore the cause–effect relationship between the ability to form morphological adaptations (hypertrophied lenticels and adventitious roots) and the capacity to maintain high assimilation rate and growth. The occurrence of morphological adaptations and the parameters of photosynthesis were monitored over 20 days of waterlogging in 5-week-old pedunculate oak seedlings presenting similar morphological development. Based on the development or not of morphological adaptations, the following three categories of responses were identified: development of hypertrophied lenticels and adventitious roots, development of hypertrophied lenticels alone, and the lack of development of adaptive structures. These categories, ranked in the order given, corresponded to decreasing levels of initial net CO2 assimilation rate growth and photosynthesis parameters observed during waterlogging. We observed a two-way cause–effect relationship between the capacity to form adaptive structures and the assimilation rate. Indeed, the initial assimilation rate determined the occurrence of hypertrophied lenticels and growth during stress, and then the development of morphological adaptations enhanced the ability to maintain assimilation levels during the stress.