Tree Layer Research Articles

Links between light availability and spectral properties of forest floor in European forests

Remote sensing using spectral data has been commonly applied to retrieve tree layer properties while the monitoring of forest floor remains a less studied topic. We investigated the links between light availability at forest floor, and forest floor's spectral reflectance properties (350–2500 nm) and fractional cover across boreal and temperate Europe. We hypothesized that tree canopy structure (and thus, light availability at forest floor) is linked not only to the vegetation composition of forest floor, as has been shown previously, but also to forest floor's spectral reflectance properties, and that these relationships differ between forest biomes. Data were collected in situ from a total of 67 forest stands in southern boreal, hemiboreal, temperate floodplain, and temperate mountain sites. The variation of light availability at forest floor was linked to both the forest floor's composition and spectral reflectance properties. Each study site exhibited site-specific spectral features and a different mean reflectance spectrum. Openness in tree canopies was related to an increase in the fractional cover of vascular plants and to a decrease of plant litter, consequently enhancing the forest floors’ spectral absorptance features in the red and shortwave-infrared wavelengths, as well as reflectance in the near-infrared region. Also, the variations of normalized difference index values and red edge positions as functions light availability at forest floor and forest floor's composition were different for each site. Our results suggest that incorporating biome-specific relationships between tree canopy structure and forest floor reflectance properties would improve interpretation of optical remote sensing data. The measurement data are openly available.

Habitat heterogeneity promotes bird diversity in agricultural landscapes: Insights from remote sensing data

Understanding the main drivers of biodiversity loss in Europe's agricultural landscapes has been a research priority in the last decades. One of the most important factors promoting biodiversity in farmed landscapes is habitat heterogeneity, which has often proved crucial for avian species and communities. Birds are highly sensitive to environmental changes and make use of a broad range of ecological niches, thus being exceptionally sensitive to the loss of habitat heterogeneity. Remote sensing data are particularly suited to quantify habitat heterogeneity at fine scales over relatively large extents, allowing to consider how different measures of heterogeneity may affect biotic communities at a regional scale. Here, we used airborne LiDAR (Light Detection And Ranging) and satellite multispectral data to derive vegetation canopy height and primary productivity for 118 sites in complex agricultural landscapes in a region in the Central Alps. We computed different bird diversity indices and classified bird species into guilds according to specific traits to analyse the relationship between avian communities and different facets of habitat heterogeneity. Results confirmed that habitat heterogeneity is essential in shaping rich and diverse bird communities, and it is particularly important for several farmland birds. By comparing the effects of canopy height, primary productivity, and specific vegetation features (e.g., cover of grassland, shrub, and tree layers), we showed how different habitat characteristics as well as landscape heterogeneity affected bird richness, diversity, functional entropy, and trait patterns. Landscape and height heterogeneity, estimated by NDVI and LiDAR Rao's Q indices, strongly influenced all response variables, for example, high NDVI values promoted species diversity and ground-understory nesters, and shrub layer was important for ground-understory nesters and forest specialists. Finally, we provide recommendations for conservation practices and mitigation measures to improve bird diversity in agricultural landscapes.

Biomass Models and Ecosystem Carbon Density: A Case Study of Two Coniferous Forest in Northern Hunan, China

The carbon sink capacity of forest ecosystem and its function of mitigating climate change have been confirmed. As two common coniferous species, Cunninghamia lanceolata (Lamb.) Hook. (C. lanceolata) and Pinus elliottii Engelmann (P. elliottii) are widely planted in southern China, and their carbon sink capacity has always been concerning. According to their diameter class, we randomly harvested 42 C. lanceolata trees and 38 P. elliottii trees from our entire study area, measured their carbon concentration, and constructed biomass models with DBH and tree height as variables. The biomass of the tree layer was estimated by measuring the DBH of all trees in the plots, and the biomass and carbon concentration of shrubs, herbs, dead wood and litter in the plot were measured by harvesting them. The results showed that the total biomass in C. lanceolata and P. elliottii plantations were 117.1 and 151.8 t·ha−1; the biomass in the tree layer was 94.7 and 122.9 t·ha−1; and in the other parts was 22.4 and 28.9 t·ha−1, respectively. In addition, the total carbon densities in the C. lanceolata and P. elliottii plantation ecosystems were 166.3 and 198.6 t·ha−1; the carbon densities in the soil were 108.1 and 124.6 t·ha−1; and in the other parts, they were 58.2 and 74.0 t·ha−1, respectively. These results indicate that there are significant differences in total biomass or total carbon storage between the two coniferous forest ecosystems, and net productivity and carbon sink capacity are higher in the P. elliottii plantation ecosystem. This study lays the foundation for the biomass estimation and carbon trading of these two coniferous forests in northern Hunan.

Identification of Tree Species in Forest Communities at Different Altitudes Based on Multi-Source Aerial Remote Sensing Data

The accurate identification of forest tree species is important for forest resource management and investigation. Using single remote sensing data for tree species identification cannot quantify both vertical and horizontal structural characteristics of tree species, so the classification accuracy is limited. Therefore, this study explores the application value of combining airborne high-resolution multispectral imagery and LiDAR data to classify tree species in study areas of different altitudes. Three study areas with different altitudes in Muyu Town, Shennongjia Forest Area were selected. Based on the object-oriented method for image segmentation, multi-source remote sensing feature extraction was performed. The recursive feature elimination algorithm was used to filter out the feature variables that were optimal for classifying tree species in each altitude study area. Four machine learning algorithms, SVM, KNN, RF, and XGBoost, were combined to classify tree species at each altitude and evaluate the accuracy. The results show that the diversity of tree layers decreased with the altitude in the different study areas. The texture features and height features extracted from LiDAR data responded better to the forest community structure in the different study areas. Coniferous species showed better classification than broad-leaved species within the same study areas. The XGBoost classification algorithm showed the highest accuracy of 87.63% (kappa coefficient of 0.85), 88.24% (kappa coefficient of 0.86), and 84.03% (kappa coefficient of 0.81) for the three altitude study areas, respectively. The combination of multi-source remote sensing numbers with the feature filtering algorithm and the XGBoost algorithm enabled accurate forest tree species classification.

Effect of Branch Bending on the Canopy Characteristics and Growth of Peach (Prunus persica (L.) Batsch)

A reasonable main branch opening angle can improve the canopy light environment of a tree, change the direction of nutrient transport, and promote the formation of flower buds. In this experiment, 3-year-old ‘Lu Hong 618’ was used as the test material to study the effects of different main branch opening angles (three treatments: 45°, 65°, and 85°) on the canopy light distribution, canopy characteristics, fruit quality, and flower bud quality of ‘Y’-shaped peach trees. The main findings were as follows: the solar energy utilization in the canopy varied greatly between different main branch opening angles, with the best relative light intensity of the canopy at 85°. In addition, the canopy light distribution on photosynthesis was more reasonable at 85°, and the daily variation range of CO2 concentration in the inner canopy was the greatest, which facilitated ventilation and light penetration in the inner canopy. With the increase in the main branch opening angle, the new growth of peach trees and the growth of the main branch trunk were inhibited. A reasonable branch opening angle results in good branch structure and leaf morphology. Leaf stomatal morphology and the soluble sugar and starch contents at different levels of the canopy are influenced by canopy light, and higher levels of canopy light can significantly increase the stomatal size and improve the leaf photosynthetic capacity, SPAD value, and soluble sugar and starch contents. With the increase in the main branch opening angle, C/N tended to increase. In addition, the distribution pattern of fruit quality in the canopy was similar to that of light distribution. In the same fruiting part, the fruit quality was higher at 85° and 45° than at 65° and slightly higher at 85° than at 45°, but the difference was not significant. The effects of different main branch opening angle treatments on the fruit weight, flesh firmness, soluble solids, and titratable acid were more significant. The 85° pulling angle effectively increased the light intensity of the different canopy layers of the peach trees and promoted the accumulation of nutrients. An 85° pulling angle can be used as a more suitable pulling angle for peach tree shaping cultivation.

Bryophyte diversity, composition and functional traits in relation to bedrock and tree species composition in close-to-nature managed forests

Bryophytes respond to a variety of environmental factors, including tree species composition and geological conditions, which are influenced by both natural and anthropogenic factors. Bryophytes growing on a variety of substrates were identified in ICP Forests monitoring plots in a wide range of close-to-nature managed forests, from lowland to high mountain areas in Slovenia. Based on data on tree layer composition (broadleaves vs. conifers) and on bedrock and soil type (calcareous vs. siliceous bedrock), all study plots were classified into five groups representing forest types. Different ordination analyses and statistical tests were used to represent differences between forest types in bryophyte composition, richness and functional traits. Almost 200 bryophyte species were identified in managed forests, with the most common being Hypnum cupressiforme, Brachytheciastrum velutinum and Polytrichum formosum. Bryophyte species composition varied considerably along the tree species composition and edaphic gradients represented by the selected forest types. Bryophyte species richness was significantly higher on calcareous bedrock than on siliceous bedrock. The higher occurrence of rocks on the ground surface may significantly increase the availability of various microhabitats for bryophytes. Bedrock had a significant influence on the functional diversity and composition of bryophytes, while tree species composition had less influence. Bedrock and tree species composition are important drivers of bryophyte species composition and diversity at taxonomic and functional trait levels. The high diversity of bryophyte species in Slovenian forests can also be attributed to close-to-nature and sustainable forest management practices that preserve favourable microclimatic conditions in forest stands and maintain diverse substrates.

Farming for nature in the Montado: the application of ecosystem services in a results-based model

The Montado is a silvopastoral system with a tree cover of predominantly Quercus suber but also Quercus rotundifolia, where cattle or sheep graze the understory. It occupies more than one million hectares in southern Portugal, and a similar landscape, the Dehesa, covers ca. three million hectares in Spain. These silvopastoral systems can simultaneously benefit the environment and socio-economic activities by providing a bundle of ecosystem services (ESs). However, an ongoing trend of decline in tree density and the covered area is threatening such provision. Policies are needed to motivate farmers to secure the ESs that they provide. One possible format is the development of a results-based model (RBM) for agri-environment schemes (AES), implemented under the Common Agricultural Policy. In an RBM, farmers are paid when they deliver specific environmental results (ERs) (e.g. healthy and functional soils), that are linked with the provision of different (and often multiple) ESs. This study defines possible ERs for the Montado and details how these results are linked to the provision of ESs. It then considers management actions that can allow the achievement of these ERs and the costs of these actions. Our methodological approach is based on a transdisciplinary dialogue involving researchers, practitioners (i.e farmers), public authorities and policy makers. The results of the process include the identification of four main ERs: a healthy soil ecosystem, a biodiverse native-Mediterranean pasture, an oak tree layer where regeneration exists (i.e. trees of different ages), and preserved or enhanced landscape elements, for example riparian galleries with vegetation. These ERs increase the supply of provisioning services (e.g. cork production), of regulating services, (e.g. carbon sequestration), and cultural services (e.g. aesthetic inspiration). RBMs allow farmers to use any management practice they choose as the focus is on the results. Nonetheless, to estimate costs we identified 12 potential strategic management practices (and their cost) along with the technical support that farmers would need. We conclude that an RBM could be an affordable solution for public policies in the Montado system, given the limited government budget for supporting AES.

The litters of spruce stands within megapolis as an object of ecological monitoring

For the purposes of ecological monitoring, the features of living ground cover and forest floor in spruce stands within Moscow urban territory were studied. Using ecological scales by Nitsenko, Ramensky, Ellenberg and Landolt, let to consider, that ruderalization of living overground cover is a result of recreation. Independently of spruce forest type, the absence of undergrowth results in increasing light penetrating and increasing species quantity. Variety of ecological spaces is a result of moderate trampling, which is mostly expressed in between-crown spaces. Hight trophy index by L.G. Ramensky is a result of increased weediness of overground cover. It is shown, that living overground cover characterizes the variety of tree layer and the level of anthropogenic impact on phytocenosis.The forest floor in urban spruce stands is sensitive to changes in functioning conditions and can be used for ecological monitoring. Availability of forest floor studying and simplicity of parameter estimation allows getting information about organic matter accumulation in express-regime under various degrees of anthropogenic impact on urban ecosystems. Within the system of trunk, crown and open space, the simplification of litter structure and decreasing organic matter total deposit are observed - this can be considered an invariant process.Maximal uniformity of coverless spaces litter, composed by needles and branches, results from absence of living overground cover, in combination with low recreation in these spaces. This fact let to conclude, that coverless spaces are able to be used as most important objects for comparing spruce ecosystems with different overground cover. Two groups of indexes, characterizing structure-functional litter organization, are proposed. Indexes, characterizing structural litter organization, include the total deposit of litter and L horizon deposit. Indexes, characterizing functional litter features, include deposit and proportion of detritus as well as the same for easydecomposed components, ratio of thickness (deposit) of L horizon and F horizon. The peculiarities of long-term spatial functioning are characterized by litter typology in the system trunk-crown-open space

Greenwood regeneration status in community forests of Chiti Lamjung Nepal

Forest regeneration is the process by which new tree seedlings become entrenched after forest trees have been harvested or destroyed by fire, insects, or diseases. The process is key to sustainable forestry and can be accomplished through natural regeneration, which occurs when new seedlings or sprouts are produced by trees left on or near the site. The study is to calculate the regeneration status of the tree species in community-managed forests. The sampling points were generated by using the random table. The sample quadrate size was taken 20m×20m for a tree, 5m×5m for a sapling, and 1m×1m for the seedling. In five community forests, altogether 30 quadrates were taken for a tree, 60 nested quadrates were taken for a sapling and 120 nested quadrates were taken for a seedling. The tree layer, sapling layer and seedling layer were differentiated by taking reference tothe Diameter at Breast Height (DBH) class. An individual having DBH ≥ 5cm is considered a tree, an individual having DBH value between 1cm to < 5cm is considered a sapling, and individuals having 1cm to < 5cm DBH are considered as a seedling. The DBH distribution curve was obtained by plotting diameter class in x- axis and density on y- axis. All studied community forests are mixed forest dominated by tree species Castanopsis indica, Diospyros embryopteris (Diospyros malabarica), Shorea robusta, and Schima wallichii (Schima wallichii choisy). The regeneration potential of the Tilahar community forest(CF) is found high despite high grazing and other human intervention. The DBH class distribution curve of tree species is found as inverse J-shape, indicating that the overall forest has a sustainable regeneration.

Dynamic variation of non-structural carbohydrates in branches and leaves of temperate broad-leaved tree species over a complete life history

The composition of non-structural carbohydrates (NSC), one of the photosynthetic products of plants, reflects the survival strategy of a plant. Although several studies have investigated variation of NSC content in woody plants over a set time scale, few studies have considered the dynamic variation of NSC over a continuous life history. In this study, the leaves, new twigs, and old branches of seven temperate broad-leaved tree species (diffuse-porous species:Betula platyphylla,Betula costata,Tilia amurensis,Acer pictumsubsp.mono; ring-porous species:Ulmus davidianavar.japonica,Ulmus laciniata,Fraxinus mandshurica) were observed at three life history stages (seedling, sapling, and mature tree) to measure the dynamic changes of NSC and its influencing factors throughout the entire life cycles of these species. The results showed that life history, wood type, and environmental factors (soil nitrogen and phosphorus content, soil pH) significantly affected the NSC content in leaves and branches (including both new twigs and old branches). As plants grew, the NSC content in the leaves and branches generally showed an upward trend, meaning the total non-structural carbohydrate (TNC) content and soluble sugar (SS) content increased significantly, and the starch (ST) content was relatively stable. Lastly, there was no significant difference in NSC content between the canopy layers of mature trees. This indicates that the influence of life stage on NSC content in leaves and branches of plants may be dominated by genetics instead of being regulated by light factors.

Canopy Composition and Spatial Configuration Influences Beta Diversity in Temperate Regrowth Forests of Southeastern Australia

Structural features of the overstorey in managed and unmanaged forests can significantly influence plant community composition. Native Acacia species are common in temperate eucalypt forests in southeastern Australia. In these forests, intense disturbances, such as logging and wildfire, lead to high densities of regenerating trees, shrubs, and herbs. The tree layer is dominated by Acacia and Eucalyptus, that compete intensely for resources in the first decades after stand establishment. The relative abundance and size of Acacia and Eucalyptus varies widely due to stochastic factors such as dispersal, microsite variability, and weather and climatic conditions. This variability may influence the structure and composition of the herbaceous and shrub species. In the temperate forests of southeastern Australia, understorey plant diversity is assumed to be influenced by Acacia species density, rather than Eucalyptus density. To quantify the influence of Acacia and Eucalyptus density on plant community composition, we used remote sensing and machine learning methods to map canopy composition and then compare it to understorey composition. We combined unoccupied aerial vehicle (UAV or drone) imagery, supervised image classifications, and ground survey data of plant composition from post-logging regrowth forests in the Central Highlands of southeastern Australia. We found that aggregation and patch metrics of Eucalyptus and Acacia were strongly associated with understorey plant beta diversity. Increasing aggregation of Acacia and the number of Acacia patches had a significant negative effect on plant beta diversity, while the number of Eucalyptus patches had a positive influence. Our research demonstrates how accessible UAV remote sensing can be used to quantify variability in plant biodiversity in regrowth forests. This can help forest managers map patterns of plant diversity at the stand-scale and beyond to guide management activities across forested landscapes.

Even minor logging road development can decrease the functional diversity of forest bird communities: Evidence from a biodiversity hotspot

Although the effects of major roads and highways on biodiversity have received considerable attention, there is a lack of research considering how smaller and less-used roads might also impact wildlife, especially during the initial re-used development phase of abandoned roads, despite these minor roads being much more extensive and pervasive. Here, we examined how even minor redevelopment of former-abandoned logging roads can impact bird community alpha and beta diversity indices at the taxonomic, functional, and phylogenetic levels in a biodiversity conservation hotspot in central China. The minor redevelopment (i.e., re-paved) of former-abandoned roads generally reduced bird alpha and beta diversity compared to undeveloped abandoned roads, especially at the functional level. Compared with continuous-use roads, minor road redevelopment shows only a slight impact on avian diversity. Notably, compared to old-growth forest reference stands and undeveloped abandoned roads, minor road redevelopments have negative effects on the recovery process of avian diversity. Furthermore, the structure and composition of the high tree layer significantly affected avian functional and phylogenetic diversity, and low shrub layer vegetation mainly influenced taxonomic and phylogenetic diversity. To mitigate the effects of minor forest logging roads on avian biodiversity in priority biodiversity conservation areas, we propose the following: (1) roads that have fallen into disuse should be allowed and encouraged to re-naturalise; (2) roads should only be paved, and cleared back as strictly necessary, allowing grassy or gravel roads to suffice where possible; and (3) if road development is necessary, key umbrella tree species should be planted deliberately to support maximal community diversity and to maintain ecosystem functions and processes.

Unmanned aerial vehicle outputs and associated field measurements of the herbaceous and tree layers of the Senegalese savannah

AbstractUnmanned aerial vehicles (UAVs) are widely used to assess the vegetation of an ecosystem. This report presents three data sets from UAVs used on a savannah‐type ecosystem in Senegal. Two data sets contain an orthomosaic and a surface and terrain digital model (UAV outputs), along with associated field measurements on the tree and herbaceous layers, while the third data set contains an orthomosaic and digital surface model, along with field measurements on the herbaceous layers. One data set was compiled over the entire rainy season on the same plot (plot dataset). One was compiled across a landscape at the 7000 ha Dahra Djoloff research center (CRZ‐dahra Centre de recherche zootechnique de Dahra). The third data set was compiled across Senegal from the North to the Southeast of the country with wide variability in climate and soil conditions. All the data sets are in Open Access in the Zenodo repository. These data sets could be used in many different studies: calibration between field measurements and UAV outputs on a large scale, or used as an intermediate step between field and satellite images.

Phytocenotic conditions and structure of the local population for Betula humilis Schrank near Zhornyska village (Ukrainian Roztochchia)

hytocoenotic conditions and structure of the local population for Betula humilis in the north-eastern environs of the village Zhornyska, Yavoriv district, Lviv region, on the territory of the Roztochchia International Biosphere Reserve have been studied. Four coenopopulations (CP) of the species are confined to secondary plant communities of sicaciogenic and pyrogenic successions with different sod levels of the peat soil, as well as missing or unequally expressed tree layer. The least transformed communities with the dominance of B. humilis (40-80% p.c.) in the shrub layer and no stands in terms of floristic composition and spatial structure correspond to the derived mesohygrophytic and hygromesophytic variants of the association Betuletum humilis Steffen 1931. The most transformed areas with sparse tree layer are represented by pioneer forest communities - birch woodlands. Seventy-five species of higher plants (seventy vascular plants and five bryophytes) were found in the floristic composition of phytocenoses. The minimal participation of helophytes and the presence of invasive species indicate a high level of mesophytization and synanthropization of modern phytocenoses. Within the locality B. humilis forms different in area and density of formation shoots (turions) of the colony-curtain mainly from semi-autonomous subpartial bushes 0.3-2.2 m tall. The largest curtains (up to 300 m2) with a high density of living formation shoots (up to 293 pcs/m2) are confined to open well-lit areas. The age of old skeletal axis, not exceeding 9 years was determined and the annual growth of shoots has been calculated. The parameters of seed productivity (SP) of the local population of B. humilis vary within: potential SP - 89.48–109.24 seed germs, actual SP - 80.84–100.4 seeds. The coefficient of seed productivity is quite high (86.69-92.16%) for all coenopopulations. Based on the results of research and analysis of the literature the life form of B. humilis, which belongs to vegetatively mobile hypogeogenic-geoxyl deciduous shrubs that form colonies or clones of (semi) autonomous (sub) partial (daughter) shrubs and are characterized by monopodial-sympodial shoots growth has been clarified. The big life cycle of the species characteristic of shrubs consists of development cycles for systems shoots formation (main skeletal axes), which are successively replaced, and lasts for decades. The development cycle of the system formation shoot covers the periods of intensive growth (appearance of formation shoot from an additional or dormant bud in the first year), relative stabilization of growth processes with the formation of first and higher-order branching shoots (from second to tenth years) and ageing and death of shoots (after about ten years of age).

Using biodiversity indices to assess the current state of tugai vegetation of the Amu Darya River, Uzbekistan

Abstract. Rakhimova NK, Shomurodov KF, Sharipova VK, Saitjanova USH, Sadinov JS. 2023. Using biodiversity indices to assess the current state of tugai vegetation of the Amu Darya River, Uzbekistan. Biodiversitas 24: 467-472. Changes in plant associations of the tugai reserve of Uzbekistan (Amu Darya coast) due to climate change were considered. The state of associations represented by the xeromesophilic-mesothermal group of plants of the tugai (POTAMODENDRA), shrub (POTAMOTHAMNA) and herbaceous (POTAMOPOIA) vegetation types of the Amudarya tugai was analyzed. At the same time, ten associations were evaluated in a comparative aspect. An analysis of biodiversity within and between associations were carried out, various biodiversity indices (Shannon, Simpson, Margalef) were compared, and the sensitivity of the indices to various factors was assessed. In the tree layer, there was a significant decrease in the abundance of Populus euphratica, P. pruinosa, as well as the number of shrubs and perennial grasses. Alarming indicators of vegetation transformation have been identified using the ?- and ?-biodiversity indices. The evaluation results of vegetation in terms of biodiversity indices showed that due to the violation of the structural and functional organization, general degradation, simplification and impoverishment of the floristic composition, change of plant communities and xerophytization, significant changes occurred in the studied associations, as reflected in biodiversity indices. The results obtained will make it possible to understand the ways of formation and development of tugai vegetation, to identify the mechanisms of transformation of tugai forests on different ecological gradients (bioclimatic, hydrological, edaphic and anthropogenic), to assess the current state of tugai forests, to identify rare plant communities that need protection and to develop recommendations for their protection.

Effects of target tree management of Pinus massoniana plantation on soil nematode community structure at different soil depths

To understand soil nematode community structure at different soil depths and its responses to target tree management, we collected soil samples (0-10, 10-20, and 20-50 cm) and litter samples from the target tree management plots and control plots of Pinus massoniana plantation and analyzed community structure, soil environmental factors, and their relationship. The results showed that target tree management increased the abundance of soil nematodes, with the most significant effect at a depth of 0-10 cm. The highest abundance of herbivores was found in the target tree management treatment, while that of bacterivores was found in the control. Compared with the control, Shannon diversity index, richness index, maturity index of nematodes at 10-20 cm soil layer and Shannon diversity index at 20-50 cm soil layer of target trees were significantly improved. According to the results of Pearson correlation and redundancy analysis, soil pH, total phosphorus, available phosphorus, total potassium, and available potassium were the main environmental factors affecting community structure and composition of soil nematodes. In general, target tree management was conducive to the survival and development of soil nematodes and promoted the sustainable development of P. massoniana plantations.

MONITORING OF VEGETATION IN PALUDIFYING SMALL LAKES IN THE LOMONOSOVSKY DISTRICT OF THE LENINGRAD REGION

The results of the vegetation monitoring in two paludifying lakes in the Lomonosovsky District of the Leningrad Region are reported. The paludification is triggered by a decline in the water level provoked by forest drainage melioration in the late 20th century. The vegetation of the lakes was first studied by V.А. Smagin in 1982–83, and was re-examined in 2004, 2014 and 2020. The composition of the bryoflora in the descriptions of 2014 and 2020 was determined by М.А. Boychuk. During the period of research, the successions were noted in lakeside mires, which led to the formation of the vegetation typical of lakeside mires. The vegetation lost its original mosaic and became more or less uniform throughout the profile, hardly distinguishable from “natural” lakeside mires. Meanwhile, in a number of places, the formation of a tree layer was noted. Beavers settled along the shores of the studied lakes, with various consequences. At one lake, the settlement of beavers turned out short-term and had no consequences, at the second one it was longer and affected the direction of successions and changes in the surrounding landscape.

Numerical Investigation of Internal Flow Properties around Horizontal Layered Trees by Using the Reynolds Stress Model

The aim of this article is to numerically explore the effects of a horizontal double layer of trees (HDLT) across the whole width of the channel on the flow structures under a steady flow rate and subcritical conditions. The numerical domain was established in ANSYS Workbench, and post-processing (i.e., meshing + boundary conditions) along with simulation was carried out by utilizing the computational fluid dynamics tool FLUENT. The three-dimensional (3D) Reynolds stress model and Reynolds-averaged Navier–Stokes equations were used to analyze the flow properties. The numerical model was first validated and then used for simulation purposes. Two varying configurations of HDLT were selected, represented as Arrangement 1 (tall emerged trees (Tt) + short submerged trees (St)) and Arrangement 2 (short submerged trees (St) + tall emerged trees (Tt)), along with different flow heights. The model accurately captured the simulated results, as evidenced by the vertical distributions of the velocity profiles and Reynolds stresses at specific locations. The strong inflection in velocity and Reynolds stress profiles was observed at the interface of St, contributing to turbulence and giving rise to vertical transportation of momentum between flow layers. While these profiles were almost constant from the beds to the tops of trees at those locations lying in taller trees (Tt), there was an approximate 31–65% increase in streamwise velocities at locations 1–6 in cases 1–2, along with a 54–77% increase at locations 7–10 in cases 3–4, in the unvegetated zone (Z > 0.035 m) compared to the vegetated zone (Z < 0.035 m). The magnitude of turbulence kinetic energy and the eddy dissipation rate were significantly larger inside the short submerged and tall emerged trees as compared to the unvegetated region, i.e., upstream and downstream regions. Similarly, the production of turbulence kinetic energy was approximately 50% and 70% greater inside the tree region (Z < 0.035 m) as compared to above the shorter trees during cases 1–2 and 3–4, respectively.

A NEWDISCOVERYOF SPARASSIS CRISPA (WULFEN) FR 1821 ON THE TERRITORY OF THE SLOVIANSKO-OVRUCH RIDGE

The article is devoted to the study of a new locality (Sparassis crispa) in the territory of the Slovak-Ovrutsky Range. The mushroom is listed in the Red Book of Ukraine and is under threat of extinction due to the growing interest in it as an object of cooking and medicine. To achieve the goal of the research, the following tasks were set: to describe the phytocenosis within which S. crispa is located and its floral environment, as well as to propose measures for its protection. The location of S. crispa is reforestation at the site of felling. The tree layer is dominated by young individuals of Pinus sylvestris L. (75-90%) with the participation of Betula pendula Roth. (20-50%). Frangula alnus Mill sometimes occurs in the undergrowth. Grass cover is sparse – up to 15%. Here, the mosses Dicranum polysetum, Dicranum scoparium, Polytrichum juniperinum and Pleurozium schreberi prevail. Festuca ovina, Lycopodium clavatum and Melampyrum pratense are occasionally found. According to the results of the synphytoindicative analysis, it was established that the environmental conditions correspond to moderately rich forests of Polissia, which belong to the Dicrano-Pinion union. The perennial wetting regime is slightly higher than the average values for the Dicrano-Pinetum association and approaches the Molinio-Pinetum association. Indicators of natural dynamics (ST=12.72 points) correspond to the transition from derived to young native forests. The level of anthropogenic transformation (HE=5.29 points) corresponds to natural oligohemerobic forests. So, despite the felling that was carried out here several years ago, the mushroom is still placed in conditions that are not subject to constant anthropogenic pressure. The phytocenosis in which Sparassis crispa is placed is the Dicrano-Pinetum association, Vaccinio-Piceetea class, Pinetalia sylvestris order, Dicrano-Pinion union. Since the "Prybytocky" hydrological reserve of local importance is being planned next to the location of the Sparassis crispa mushroom, it is expedient to include this territory in the projected PZF object.

Giant Panda Microhabitat Study in the Daxiangling Niba Mountain Corridor.

Habitat reduction and increased fragmentation are urgent issues for the survival and recovery of the giant panda (Ailuropoda melanoleuca). However, changes in the distribution and microhabitat selection of giant panda habitats in different seasons in the same region have rarely been assessed. To further understand giant panda habitat requirements, this study analyzed the giant panda habitat selection characteristics and differences using the sample data of the giant panda occurrence sites collected during 2020-2022. The results showed that the giant panda in both seasons selected medium altitudes (2000-2400 m), southeastern slopes, slopes less than 15°, taller tree layers (8-15 m) with a larger diameter at breast height (17-25 cm) and medium density (25-55%), shorter shrub layers (<4 m) with sparse density (<30%), and taller bamboo (>2 m) with high density (>35%). The giant panda microhabitat survey in the Niba Mountain corridor clarified the characteristics of suitable habitat selection for the giant panda in the corridor. The findings of the study can provide scientific references for the development of practical habitat conservation and management measures for giant pandas in the study area.