Well-developed Crowns Research Articles

Acorn production of pedunculate oak in northeast of Ukraine

Abstract We analysed the quantity and quality of Quercus robur L. acorns after years with a very poor yield under the canopy of natural oak stands of various compositions, ages and stock densities in the northeastern part of Ukraine. We determined the mass of 1,000 healthy and damaged acorns of the current year. The levels of variability were estimated for the number and mass of acorns under the canopy of the studied stands. The dependences of the number of acorns on the age of oak stands and their stock density were studied. The total number of acorns under the canopy of natural oak stands was 9,900–19,000 seeds per hectare with a total mass of 26.8–54.1 kg per hectare in 2020 and 8,600–17,200 seeds per hectare with a total mass of 22.7–48.4 kg per hectare in 2021. The proportion of damaged acorns was about 70% both in 2020 and 2021. The largest number of acorns was concentrated under healthy trees (without signs of decline) that had a well-developed crown and, therefore, received more sunlight and heat. The identified quantitative and qualitative estimates and acorn spreading pattern need to be considered when selecting sites for further natural seed regeneration in old-aged oak stands.

A multi-feature predicting model of crown evolution involving material properties

We propose a new model for the crown evolution after a single drop impacts on a thin film. In contrast with the existing models that mainly focus on the status of well-developed crown or the bottom radius evolution, multiple features are provided in our model, including the temporal evolution of the crown radius, height, velocity, and the characteristic time when the crown reaches its maximum height. Both the fluid viscosity and surface tension are considered in this work rather than ignoring one or both of them as in previous studies, resulting in improved accuracy for crown development prediction. The new model can be applied for droplets of various fluids impinging on relatively thin films (0.1 < δ < 0.67). The reliability of the model is validated via comparing results with five cases of droplet impact experiments.

Ground-based “Pot-in-Pot” system and its effectiveness in growing Thuja occidentalis “Smaragd” planting material in a nursery

For the sparsely wooded regions of Russia, and in particular, the Central forest-steppe, new technologies for growing seedlings and seedlings of tree species are extremely important. It provids rapid growth and high survival rate, which is compared to classic technologies. The purpose of our experiment was to establish the effect of temperature screens from pots of various sizes on the temperature in the root zone of the substrate, and, as a consequence, on the growth and productivity of Thuja occidentalis “Smaragd” in plastic pots for three seasons. The most favorable temperature conditions for plants are formed in large pots, which is facilitated by smooth temperature drops in the substrate and a large area of contact between the substrate and the root system. Agrotechnical methods of growing plants have shown the main advantages of “Pot-in-Pot” technology. This is accelerated plant growth due to more efficient use of water and fertilizers on a specially prepared substrate under conditions of minimal temperature fluctuations. Plants, especially large ones, will have a favorable presentation due to better leafing, a well-developed crown, and a large crown diameter. High safety during wintering also increases the efficiency of the technology providing a higher yield and subsequent more intensive growth.

Variations in morphological and epidermal features of shade and sun leaves of two species: Quercus bambusifolia and Q. myrsinifolia.

Microclimatic differences between the periphery and the interior of tree crowns result in a variety of adaptive leaf macromorphological and anatomical features. Our research was designed to reveal criteria for sun/shade leaf identification in two species of evergreen oaks, applicable to both modern and fossil leaves. We compared our results with those in other species similarly studied. For both Quercus bambusifolia and Q. myrsinifolia (section Cyclobalanopsis), leaves from single mature trees with well-developed crowns were collected in the South China Botanical Garden, Guangzhou, China. We focus on leaf characters often preserved in fossil material. SVGm software was used for macromorphological measurement. Quantitative analyses were performed and box plots generated using R software with IDE Rstudio. Leaf cuticles were prepared using traditional botanical techniques. Principal characters for distinguishing shade and sun leaves in the studied oaks were identified as leaf lamina length to width ratio (L/W), and the degree of development of venation networks. For Q. myrsinifolia, shade and sun leaves differ in tooth morphology and the ratio of toothed lamina length to overall lamina length. The main epidermal characters are ordinary cell size and anticlinal wall outlines. For both species, plasticity within shade leaves exceeds that of sun leaves. Morphological responses to sun and shade in the examined oaks are similar to those in other plant genera, pointing to useful generalizations for recognizing common foliar polymorphisms that must be taken into account when determining the taxonomic position of both modern and fossil plants.

GINKGO BILOBA L. (GINKGOACEAE) AT PETER THE GREAT BOTANIC GARDEN OF BIN RAS

Ginkgo biloba L. has been known at Peter the Great Botanic Garden of the Komarov Botanical Institute RAS (Saint-Petersburg, Russia) since 1816. In modern collection it is represented since 1947, in vegetative state. In these conditions, it forms a well-developed tree with a single trunk and a well-developed crown; the best specimens have reached a height of 15.5 m at the age of 74 years old. Compared to previously published data, its size has increased significantly. The dates of phenostages of its seasonal rhythm of development correspond to the local Calendar of Nature; it is not damaged by spring and autumn frosts. The maximum percentage of rooting from cuttings was 88,5 %.The species may be recommended for Saint-Petersburg’s city planting. Earlier there was an opinion that Leningrad (Saint-Petersburg, not Kharkov) is the northern border of Ginkgo cultivation in living form of a tree (Komarova, Zamjatnin, 1990), but nowadays, in the second decade of the XXI century, its distribution may be prolonged further up to the North.

Chiral Macrocycle-Enabled Counteranion Trapping for Boosting Highly Efficient and Enantioselective Catalysis.

The tight binding enabled by tailor-made macrocycles can be manipulated for tuning the catalysis process. In parallel to well-developed crown ether-based cation-binding catalysis, a macrocycle-enabled counteranion trapping strategy is presented for boosting highly efficient and enantioselective catalysis. A set of bis-diarylthiourea macrocycles containing two BINOL moieties were designed and synthesized. They possess a well-confined chiral cavity and strong binding affinities towards disulfonate anions. Caused by the tight binding, just 1 mol % macrocycle in combination with 1 mol % ethanedisulfonic acid can promote excellent conversion and up to 99 % ee in the Friedel-Crafts reaction of indoles with imines. The acid or the macrocycle alone do not afford any reactivity. The high catalytic efficiency and excellent stereocontrol was ascribed to large, complexation-induced acidity enhancement and tight ion-pairing facilitated by cave-like macrocyclic cavity.

Growth of Tilia cordata Mill. in Urban Forests

Tilia cordata Mill. is considered to be the main tree species resistant to urban conditions and it is widely used in the greening of cities. The aim of the study is to assess the patterns of growth and development of small-leaved linden plantations in the urban environment. The research is based on the method of sample areas where continuous enumeration survey has been carried out. The study of urban greening objects was conducted using the methods of landscape assessment and complete enumeration of trees in alley plantings. It was found that Tilia cordata Mill. grows in all districts and zones of the city of Ufa, occupying 34.4% of green areas. During this research it was found that artificially created alley plantings of Tilia cordata Mill. are more well-kept and have well-developed crowns which create a tree shade sometimes 8-10 meters wide (the average crown projection being 7 m). Since alley plantings have repeatedly been pruned, trees in this area are characterized by a large increase in diameter and strong height growth stagnation. Thus, when studying linden plantings of the same age, a sharp difference in the size and shape of trees was observed.

Екологічна роль глибокої омолоджувальної обрізки представників роду Populus в зелених насадженнях міста Житомир

Вивчено вплив глибокого омолоджувального обрізування на дерева роду Populus. Визначено, що на 2018 р. фітосанітарний стан дерев тополі пірамідальної (Populus pyramidalis Rozier) на дослідних майданчиках добрий та задовільний. Більшість дерев (70–80 %) здорові без ознак захворювань, з добре розвиненими кронами, близько 10 % досліджуваних дерев – з ознаками захворювань, від 2 до 7 % дерев перебувають у сильно пригніченому, або відмираючому стані (така тенденція зберігається і на контрольному майданчику). Виявлено пряму залежність між запиленістю повітря на дослідних ділянках та осіданням пилу на листкових пластинах тополі колоноподібної (Populus pyramidalis Rozier). Коефіцієнт кореляції становить 0,94, що свідчить про високий ступінь зв'язку між досліджуваними показниками. Естетична привабливість представників виду Populus pyramidalis Rozier після проведення глибокої омолоджувальної обрізки відновлюється на другий рік після виконання робіт. В інших видів цей процес триваліший: повернення естетичної привабливості для представників роду Tilia L. відбувається на 3–4-ті роки після вживання агротехнічних заходів. Встановлено, що дерева тополі колоноподібної (Populus pyramidalis Rozier) після глибокого омолоджувального обрізування зберігають високі екологічні та естетичні властивості, перспективні та повністю виконують фітомеліоративні й захисні функції.

Многолетний опыт по влиянию рубок ухода на нагорные искусственные насаждения дуба черешчатого южной лесостепи

The results of a 60-year experience on the effect of thinning on the stability and productivity of the stand of English oak of artificial origin in the Tellerman experimental forestry of the Institute of Forestry of the Russian Academy of Sciences have been summed up. Cleaning cuttings was carried out on permanent trial plots in 2 ways - by the grassroots method and by method of V.G. Nesterov with an intensity of up to 35% in stock 3 times. In the long-term dynamics, the ranking of stands on the average height and diameter, the number of trunks and the sum of cross-sectional areas, stock and total productivity, given by the intensity and the method of thinning, was mainly preserved. With increasing felling intensity, regardless of their method, relative increment and change in the stock have increased. In conditions of periodic moisture deficiency and accompanying damage to the leaves by insects, the stands could not restore previous trajectory of stock after the third felling. After 60 years of age, the stock of forest stands has not practically increased. Regardless of the intensity and the method, cleaning cutting contributed to the stability of growth rate of the stands. In the control, the stock decreased as a result of wave detachment, including large trunks. The stock of large trunks by the age of 80 years in the options with cutting was higher than in control one by an average of 17%. In order to reduce the risk of stock reduction by the age of ripeness in the upland oak forests of the southern forest-steppe, it is recommended to limit the period of intensive cutting up to 40 years. In this case, the trees will be able to form well-developed crowns at the end of the period of rapid growth. During unfavorable periods there is a decrease in the productivity of plantations and a decrease in the effect of thinning, which is important to take into account when predicting the growth of stands.

Wettability and interception in relationship with the seasonal changes on the Fagus sylvatica leaf surface

Abstract Interception is the amount of water held on the canopy at the end of a rainfall event. Rainfall interception and contact angle of raindrops on the surface of plants has a significant meaning in ecohydrology. Leaves are the plant organs in which during development, changes in the composition of the epicuticular wax can be observed. These differences can be explained by phenological changes. In the present study, there was a hypothesis that seasonal phenological changes of leaf surface can highly affect the amount of rainwater retained by plants (interception) and the angle of contact between the droplets and leaf’s surface. This above-mentioned hypothesis was assessed based on the designed measurement series, combining: 1) direct leaves spraying in various stages of growth with water at a constant temperature 2) images obtained by scanning electron microscope (SEM) to analyse changes in the structure of the epicuticular wax 3) photographic methods, images acquired in the light box 4) measurement and analysis of the angle of contact by using simulated raindrops. The leaves of Fagus sylvatica L. were analysed. Samples were taken in the Niepołomice Forest District (southern Poland) from well-developed crown trees. The result of the experiments conducted makes a database of changes in wettability of raindrops on beech leaves throughout the whole vegetative season. The internal slope of drops ranged from 110°–150° in April up to 20°–40° at the beginning of November. Based on the obtained results, we can classify the degrees of leaf wettability and interception under the influence of morphological changes occurring during the vegetative season.

Seasonal variability of interception and water wettability of common oak leaves

Wettability of leaves and the resulting amount of interception loss of tree crowns is an important component of the atmosphere-tree stand-soil system balance. In the study, we hypothesized that changes occurring in leaves during the vegetation period can significantly affect the amount of rainwater retained by plants and wettability of leaves which is expressed by the contact angle between drops and leaves. We evaluated the hypothesis based on measurement series, which combined direct spraying of leaves with water at different stages of development at a constant temperature with observations made with an electron scanner which was used to determine changes occurring within a leaf, while the photographic method was used to analyze the contact angle of drops. The study involved common oak (Quercus robur). Samples of twigs derived from this species were collected in the area of Przedborz (Poland) forest district, in particular from the trees with well-developed crowns. Twigs were collected from 10 trees of similar age (35–40 years). The resulting database contained experimental data on changes of raindrop adhesion on oak leaves throughout the growing season. The internal contact angle of drops was within the range of 150° on the upper side of the leaf and 160° on the underside in May, up to 15° and 35° in November on the upper and underside of the leaves. Loss of interception was established at 6% at the beginning of the growing season up to 22% in autumn. It was concluded that the wettability and the level of interception increases in line with the age of a leaf.

Site requirements of the endangered rosewood Dalbergiaoliveri in a tropical deciduous forest in northern Thailand

Planting native trees may complement and accelerate natural regeneration and support recovery of biodiversity in degraded forests. Before planting trees, however, there is a need for species-specific site selection criteria. This study investigates the site requirements of a valuable but endangered rosewood species, Dalbergia oliveri, with the purpose of restoring degraded deciduous forest in northern Thailand. The study was conducted in the Ban Pong Forest near Chiang Mai in northern Thailand. We determined site characteristics of plant communities where D. oliveri occurred with indirect gradient analysis and used the importance value index (IVI) to determine the social position of D. oliveri compared to the dominant tree species. The forest was dominated by fire-tolerant dipterocarps. D. oliveri was a co-dominant component in two communities, mixed deciduous forest and the mesic phase of the deciduous dipterocarp forest, on deeper soils of the foothills and on less sun-exposed slopes. In dry deciduous dipterocarp forest, on the driest or steepest slopes with shallow soil, D. oliveri was an emergent or canopy tree with exceptionally well-developed crowns compared to the much smaller, but numerous dipterocarps. In conclusion, D. oliveri existed across a range of environmental limiting factors within various forest facies of deciduous forest in northern Thailand, and therefore, is likely a suitable candidate for restoration of degraded forests. On highly degraded sites the species can assist in restoring a more mesic forest microclimate. Planting or sowing D. oliveri in degraded forests may help to reduce pressure on the remaining wild rosewood populations, and serves in both conservation of biodiversity and economic production.

Effects of Management on the Composition and Structure of Northern Hardwood Forests in Upper Michigan

Abstract To improve our understanding of how management affects the composition and structure of northern hardwood forests, we compared managed with unmanaged sugar maple (Acer saccharum Marsh.) dominated forests. Unmanaged old-growth and unmanaged second-growth forests provided baselines for comparing the effects of even-aged and uneven-aged forest management on selected aspects of biological diversity. Three replications of each condition were located on the Winegar Moraine in Michigan's Upper Peninsula. Old-growth forests were multistoried, dominated by a few, large trees with well-developed crowns extending over a subcanopy stratum 10–15 m in height and an abundance of woody vegetation (mostly sugar maple seedlings) at 2–3 m. This complex stand structure contrasts with the relatively uniform structure of unmanaged second-growth forests with a closed overstory canopy and limited understory development. Forest management, both even- and uneven-aged, created forest structures that were more complex than their unmanaged second-growth baselines, yet managed forests lacked some of the structural complexity characteristic of old-growth. Managed forests had fewer large trees (stem diameter at 1.37 m > 50 cm) and considerably less basal area in dead trees when compared with old-growth. There were fewer tree species in managed forests because commercially important tree species were favored for retention and, when present, early successional species (e.g., Populus grandidentata Michx., Populus tremuloides Michx.) were harvested. A subcanopy comprised of large shrubs and small trees characteristic of old growth was absent in managed forests, but this structural element may develop with time under management. As expected, thinning the overstory and disturbing the forest floor through tree harvesting promoted understory development in managed forests. Most of the added species, however, were common in the landscape and thus added little to overall species richness. FOR. SCI.48(1):129–145.

Optimization of callus culture and shoot multiplication ofAsparagus densiflorus

The effects of different growth regulators on induction and growth of callus ofAsparagus densiflorus cv. Sprengeri were studied. Calluses grew more rapidly on Murashige and Skoog basal medium supplemented with 5.4 μM p-chlorophenoxyacetic acid (pCPA) and 4.4 μM 6-benzylaminopurine (BA) (medium 1) as compared to the same medium with 11.3 μM 2,4-dichlorophenoxyacetic acid (2,4-d) and 4.6 μM kinetin (medium 2). Calluses on medium 1 were soft and friable, whereas, compact, hard calluses originated on medium 2. Different concentrations and combinations of BA and/or kinetin were also used to study their effects on shoot regeneration. Kinetin was found to be less effective than BA in the initiation of shoots (1.8 shoots/callus). High numbers of shoots were produced in the presence of 0.4 μM BA alone (3.3 shoots/callus). The addition of ancymidol (5 μM) in MS with 0.4 μM BA enhanced multiplication of shoots (9.8 shoots/explant) and also produced well-developed crowns.

Radiative transfer modelling of discontinuous tree canopies at microwave frequencies

Development of a first-order radiative transfer model for predicting backscatter from tree canopies has been underway at the University of Michigan Radiation Laboratory for some time. This model is known as the Michigan Microwave Canopy Scattering (MIMICS) model. This article presents the second-generation MIMICS model (MIMICS II) which accounts for canopies with discontinuous (open) crown layer geometries. MIMICS II models open crown layers by treating the location, size, and shape of the individual tree crowns as random variables. The backscattering coefficients for the canopy are then determined by introducing statistics derived from these parameters into the radiative transfer solution. Application of the radiative transfer equations to the discontinuous canopy geometry is presented. The resulting model is a robust fully polarimetric solution that is applicable over a wide variety of canopy architectures. Model simulations are compared to results generated with the continuous canopy model. The effect of the open crown geometry is found to be most significant at shallow incidence angles and at high frequencies for trees with well-developed crowns. Under these conditions, the gaps in the crown layer give rise to a notable increase in crown layer transmissivity which allows the radar to see through to the lower layers of the canopy more easily, thereby directly affecting the backscatter contribution of the trunks and ground.