Topographic Features Research Articles

Evaluation of statistical and machine learning models using satellite data to estimate aboveground biomass: A study in Vietnam Tropical Forests

The combination of machine learning models with satellite imagery is becoming a popular data-modeling tool for biomass prediction, supporting land cover management. This study aims to select the most suitable model to estimate tropical forest aboveground biomass in Vietnam, helping to manage and monitor changes in biomass at regional and local scales. The study identified the optimal model for estimating forest aboveground biomass and minimizing the number of input variables while achieving satisfactory model performance. A total of 59 input variables, including topography, texture features, and vegetation indices, from satellite data were used in four non-parametric algorithms and a conventional parametric model, Artificial Neural Networks (ANN), Support Vector Machine (SVM), Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Multiple Linear Regression (MLR) to predict biomass and evaluate changes aboveground biomass over 10 years in two tropical forests in Vietnam. The results indicated that all models had good estimation performance with R2 ranging from 0.615 to 0.754. For RF, MLR, and XGBoost, vegetation indices contributed the highest model weights, occupying 77.71% – 92.48%. For ANN and SVM, textural and topographic features were the majority of the model weights (73.74 – 96.36%). The RF model performed the best using 59 variables (R2 = 0.754, MAE = 78.5 Mg·ha−1, and %RMSE = 13.57%) and ten variables (R2 = 0.745, MAE = 85.8 Mg·ha−1, and %RMSE = 16.17%). The biomass map using the RF and ten variables achieved a good degree of fitting of 0.76, so it was suitable for managing and monitoring forest biomass in Vietnam. The results indicated a sharp decrease in the areas of dense and very dense forests from 2013 to 2021 and a gradual increase in 2023.

공주시 마곡사 부속 건물군 배치의 지형적 입지 특성

공주시 마곡사 부속 건물군 배치의 지형적 입지 특성

Examining the Impact of Topography and Vegetation on Existing Forest Canopy Height Products from ICESat-2 ATLAS/GEDI Data

Forest canopy height (FCH) is an important variable for estimating forest biomass and ecosystem carbon sequestration. Spaceborne LiDAR data have been used to create wall-to-wall FCH maps, such as the forest tree height map of China (FCHChina), Global Forest Canopy Height 2020 (GFCH2020), and Global Forest Canopy Height 2019 (GFCH2019). However, these products lack comprehensive assessment. This study used airborne LiDAR data from various topographies (e.g., plain, hill, and mountain) to assess the impacts of different topographical and vegetation characteristics on spaceborne LiDAR-derived FCH products. The results show that GEDI–FCH demonstrates better accuracy in plain and hill regions, while ICESat-2 ATLAS–FCH shows superior accuracy in the mountainous region. The difficulty in accurately capturing photons from sparse tree canopies by ATLAS and the geolocation errors of GEDI has led to partial underestimations of FCH products in plain areas. Spaceborne LiDAR FCH retrievals are more accurate in hilly regions, with a root mean square error (RMSE) of 4.99 m for ATLAS and 3.85 m for GEDI. GEDI–FCH is significantly affected by slope in mountainous regions, with an RMSE of 13.26 m. For wall-to-wall FCH products, the availability of FCH data is limited in plain areas. Optimal accuracy is achieved in hilly regions by FCHChina, GFCH2020, and GFCH2019, with RMSEs of 5.52 m, 5.07 m, and 4.85 m, respectively. In mountainous regions, the accuracy of wall-to-wall FCH products is influenced by factors such as tree canopy coverage, forest cover types, and slope. However, some of these errors may stem from directly using current ATL08 and GEDI L2A FCH products for mountainous FCH estimation. Introducing accurate digital elevation model (DEM) data can improve FCH retrieval from spaceborne LiDAR to some extent. This research improves our understanding of the existing FCH products and provides valuable insights into methods for more effectively extracting accurate FCH from spaceborne LiDAR data. Further research should focus on developing suitable approaches to enhance the FCH retrieval accuracy from spaceborne LiDAR data and integrating multi-source data and modeling algorithms to produce accurate wall-to-wall FCH distribution in a large area.

Investigation of electrical, dielectric and multiferroic properties of 0.7Bi0.95Sm0.05Fe1-xGaxO3-0.3BaTiO3 composite ceramic system for high temperature piezoelectric applications

Lead-free composite ceramics, 0.7Bi0.95Sm0.05Fe1-xGaxO3-0.3BaTiO3 (BSFGx-BT), were made using a solid-state reaction method for x = 2.5, 5, 10, 15, and 20 %. We have investigated the effects of Samarium (Sm) and Gallium (Ga) co-doping on the crystal structure, topography, spectroscopy, electrical and multiferroic characteristics of the 0.7BiFeO3-0.3BaTiO3 (0.7BFO-0.3BTO) system for piezoelectric applications. The structural results indicate that the composite ceramics exhibited rhombohedra R and tetragonal T phases characterized by R3c and P4mm space groups, respectively which was also further confirmed by X-ray Rietveld refinement pattern analysis. In dielectric behaviour study high Curie temperature of 550 °C was obtained with high temperature stability. Furthermore, the study investigated the effects of grain and grain boundaries on capacitive and resistive properties. The ceramics displayed the characteristics of the negative temperature coefficient of resistance (NTCR). It was observed that as the Ga concentration increased, the grain resistance (Rb) also increased, reaching its maximum value for x =10 %. Additionally, at higher temperatures, this composite exhibited lower electrical resistivity. Importantly, the ceramics showed the co-existence of ferromagnetic and ferroelectric behaviour with the enhanced values of remanent magnetization (Mr)= 0.043 emu/g, coercivity (Hc) = 5730 Oe and remanent polarization (Pr) = 6.07 µC/cm2, coercive field (Ec) = 6.78 kV/cm for the composition x =10 %. These findings suggest that Sm & Ga incorporated 0.7BFO-0.3BTO composite ceramics can show promising high-temperature piezoelectric applications.

A Study of Tribological Performance Prediction Based on Surface Texture Parameters

Surface texture parameters are a quantitative way of characterising surface topographical features and are closely related to tribological properties. In this paper, the correlation between surface topographic features and friction coefficient is investigated on the basis of the proposed improved correlation analysis model for high-speed milling surface topography of hardened steel. It was found that the friction coefficient could not be accurately reflected by a single parameter, so a prediction model for the friction coefficient based on Sxp, Sq, Sp, Sz, Sku and Sdq was developed. In this paper, the parameter screening was completed based on the changing characteristics of the data, and a multi-parameter prediction model of the friction coefficient in the stable wear stage was established, which provides a new idea to investigate the influence of the characteristics of surface topography on tribological performance.

Understanding scale effects and differentiation mechanisms of ecosystem services tradeoffs and synergies relationship: A case study of the Lishui River Basin, China

Understanding the scale effect of relationships among ecosystem services (ESs) and the factors influencing these relationships, is vital for sustainable management of ESs. Previous research has focused less on multiple scale units, and the driving mechanisms behind ESs interactions remain unclear. Therefore, in this study, we assessed the spatial distribution of water yield (WY), water purification (WP), and soil conservation (SC) across four spatial scales (3 km × 3 km grid, 5 km × 5 km grid, sub-watershed, and county scales) in the Lishui River Basin of China during 2020. Using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, geographical weighted regression, and Pearson correlation analysis, we examined tradeoffs and synergies among these ESs at various scales. Additionally, we employed a geographic detector to analyze the reactions and scale effects among these tradeoffs/synergies and social-ecological factors. Our findings revealed the following: (1) Significant spatial heterogeneity in ESs was observed in the basin. The WY decreased from west (2511.65 mm) to east (890.06 mm), with high WP values concentrated in the eastern part, and high SC values (8.30 × 105 t/hm2) found in densely forested and grassland areas surrounding water bodies. Forested and cultivated lands were key contributors to ESs in the basin. (2) Across the four investigated scales, tradeoffs or synergies between the same ESs becoming more pronounced as the scale increased. Notably, most ES relationships displayed their strongest synergies at the county scale, with certain spatial areas demonstrating change in interaction directions. (3) The explanatory power of single- or double-factor interactions increased with scale. ESs interactions were found to be closely linked to climatic factors, as well as topographic features (including slope gradient and elevation), with precipitation exhibiting relatively high explanatory power. The interaction of natural and social factors significantly outweighed the combined interaction of dual social factors. This indicated that socio-ecological factors, especially climate and topography, jointly influenced the intensity and direction of ES tradeoffs/synergies. Scale effects arose from the “peak cutting and valley filling” phenomenon during scale transitions. These insights hold significant value for guiding hierarchical management strategies for regional ESs and informing decisions regarding resource allocation.

Flooding Hazard Vulnerability Assessment Using Remote Sensing Data and Geospatial Techniques: A Case Study from Mekkah Province, Saudi Arabia

Flash floods are catastrophic phenomena that pose a serious risk to coastal infrastructures, towns, villages, and cities. This study assesses the risk of flash floods in the ungauged Mekkah province region based on specific and effective morphometric and topographic features characterizing the study region. Shuttle Radar Topography Mission (SRTM) data were employed to construct a digital elevation model (DEM) for a detailed analysis, and the geographical information systems software 10.4 (GIS) was utilized to assess the linear, area, and relief aspects of the morphometric parameters. The ArcHydro tool was used to prepare the primary parameters, including the watershed border, flow accumulation, flow direction, flow length, and stream ordering. The study region’s flash flood hazard degrees were assessed using several morphometric characteristics that were measured, computed, and connected. Two different and effective methods were used to independently develop two models of flood vulnerability behaviors. The integrated method analysis revealed that most of the eastern and western parts of the studied province provide high levels of flood vulnerability. Due to it being one of the most helpful topographic indices, the integrated flood vulnerability final map was overlayed with the topographic position index (TPI). The integrated results aided in understanding the link between the general basins’ morphometric characteristics and their topographical features for mapping the different flood susceptibility locations over the entire studied province. Thus, this can be applied to investigate a surface-specific reduction plan against the impacts of flood hazards in the studied landscape.

Pleomorphic Adenoma of Hard Palate: A Case Report

Salivary gland tumors are rare and account for only 2-3% of head and neck tumors, most of which are benign. Pleomorphic adenoma is the most common salivary gland tumor. This tumor mostly involves the parotid gland. However, if it occurs in the minor salivary glands, the palate is the most common site, followed by the lips, buccal mucosa, floor of the mouth, tongue, tonsils, pharynx, retromolar trigone, and gingiva. It usually presents as a slow-growing, painless submucosal mass on the hard palate. For a definitive diagnosis, it is necessary to perform a preoperative core biopsy for histopathological examination and Computed Tomography to evaluate the erosion of the hard palate and the severity of the erosion. We aim to describe the clinical, and radiological features, as well as the management of this rare localization of pleomorphic adenoma. In this case, a 30-year-old Iranian male patient with pleomorphic adenoma of the small salivary glands of the hard palate with the chief complaint of painless swelling on the left side of the palate for the past 5 years was reported. Although pleomorphic adenoma is a common entity, it is still a challenging tumor for pathologists, radiologists and surgeons. Various histological and topographic features make this tumor unique. Computed tomography and correct histopathological diagnosis are necessary to establish an appropriate surgical treatment, to achieve complete removal of the lesion through extensive local excision with periosteum or bone removal if involved to prevent recurrence.

Impact of passivation on GaS nanoflakes: A study on stability, electronic, spectroscopy, and photocatalytic properties

This study uses first-principle calculations to investigate the properties of pristine and passivated gallium sulfide nanoflakes. Passivation significantly enhances stability, with fluorinated nanoflakes being the most stable and pristine nanoflakes the least stable, having formation energies of −0.058 eV/atom and −0.009 eV/atom, respectively. The pristine and passivated nanoflakes show semiconducting band gap, which lies in a visible region. Hydrogenated nanoflakes exhibit the largest band gap of 3.62 eV, making them highly suitable for photocatalysis, while fluorine and chlorine passivation result in band gaps of 3.16 eV and 3.01 eV. Scanning tunneling microscopy reveals distinct topographical features for each passivated nanoflake, affecting their electronic properties, including negative differential conductance, making it suitable for advanced switching devices and sensors. The quantum capacitance value of 815 µF/cm2 for chlorinated nanoflakes suggests that passivated nanoflakes could be beneficial for supercapacitor applications. Spectroscopic studies show that passivation changes the infrared spectrum and moves absorption spectra from the ultraviolet to the visible range. The hydrogenated nanoflakes are found ideal for water splitting, and adjusting the pH can further optimize its photocatalytic performance. These findings highlight the potential of passivated nanoflakes in photovoltaics, biomedical imaging, photocatalysis, and advanced technological devices.

Archaeological Excavation, Protection, and Display Engineering Design Practice: A Case Study in the Ruins of the Imperial City of the Minyue Kingdom

The Han Dynasty Ruins in Chengcun Village of Wuyishan City, also known as the Ruins of the Imperial City of the Minyue Kingdom, are located on the hilly slope southwest of Chengcun Village, Xingtian Town, Wuyishan City, Fujian Province, China. These are ruins of a Han Dynasty city. Wuyi Mountain’s World Cultural and Natural Heritage Committee declared it a World Heritage Site in 1999. It is also the only imperial city site from the Han Dynasty that has been declared a World Heritage Site in China, and it is the most well-preserved large-scale imperial city site from the Middle Ages on the Pacific Rim. This study used comprehensive archaeological techniques, including archaeological excavation work, site information recording, erosion situation analysis, and geological surveys, to design and implement protective engineering projects in response to existing problems. In this study, the researchers conducted a geological survey of the study area to analyze the topography, rock and soil distribution characteristics, groundwater storage conditions, and geotechnical engineering conditions. At the same time, they explored the preservation status of the site, including the preservation status of the East Gate and the East City Wall, and they analyzed the causes of damage. Finally, the investigation and analysis results guided the design of a site display project, which included safeguarding against collapse and erosion, treating trees and shrubs, and designing the exhibition project for the East Gate. This study provides some practical reference for the excavation and archaeological work of the royal city in the surrounding areas. At the same time, in terms of the technical process of the project, it is also hoped to provide ideas for international ancient city excavation, display, and protection projects.

Shedding light on the geographical distribution, population size and inflorescence coloration variety of Royal Irises (Iris section Oncocyclus) family in West Bank, Palestine

Palestine has rich floristic diversity due to its location, diverse biogeographical zones, and various topographical features. The Royal Irises (Iris section Oncocyclus), are a monophyletic group of herbaceous geophytes, consisting of 33 species, endemic to the Middle East. Within the West Bank of Palestine, three Royal Irises are documented. However, their distribution, population size, and status are not studied comprehensively. This study focused on evaluating the occurrence, distribution range, population size, status, number of flowers, inflorescence coloration variety, and habitats of the vulnerable and endemic Iris haynei, the endangered and sub-endemic Iris lortetii, and the vulnerable and sub-endemic Iris atrofusca. I. lortetii was found in 10 sites within Nablus district, with more than 12625 clones and 25088 flowers flowers recorded. I. haynei were documented in 4 sites within Jenin district, three are new to science, where 10729 clones and 9562 flowers were recorded. I. atrofusca was reported in 13 localities in Tubas and Ramallah districts, where 1853 clones and 8460 flowers were recorded, whereas six locatities are new to science. 12, 12, and 7 unique variations in coloration of inflorescences were observed for I. lortetii, I. atrofusca, and I. haynei, respectively. The results indicate that the population size and the distribution range of the three Royal Irises are larger than previously reported, whereas the documented inflorescences’ coloration variations are unique and considerable. This study sheds light on hotspot occurrence sites of endangered and vulnerable species in Palestine, which can assist in laying adequate conservation actions and management plans in the future.

Debris‐flow fan channel avulsions: An important secondary erosional process along the Ichino‐sawa torrent, Japan

AbstractSediment transported from debris‐flow initiation zones is typically stored in a topographic feature called a debris‐flow fan, the formation process of which governs secondary sediment transport further downstream. Although sediment transport from debris‐flow fans can impact sediment regimes and change landforms, the determinants of progressive fan formation are not well constrained. To identify such determinants, this study monitored debris flows and performed topographic surveys of debris‐flow fans in the Ichino‐sawa torrent (Japan) during 2016–2017. In this period, eight debris flows occurred, two of which eroded the existing fan and formed a new channel with a short recurrence interval (~40 days). Consequently, these two cases induced substantial sediment transport further downstream from the fan. The examined rainfall indices did not provide a threshold for diagnosing the occurrence of such sediment transport. Debris flows with a large flow depth and a long duration led to changes in the runout direction and subsequently formed new channels. Before these processes, the existing channel was backfilled and plugged by previous debris flows, forming a steep fan surface around the fan apex. The results suggest that increasing the magnitude and the duration of debris flows potentially triggers sediment transport from fans coupled with channel plugging. The annual sediment transport from the fan exceeded almost all sediment yields of the world rivers and was found comparable with that linked with volcanic eruptions and their aftermath. Thus, the fan‐formation process can induce substantial sediment transport, independent of volcanic perturbations and extreme climatic events, and is dependent on the sediment supply from repeated occurrence of debris flows in the initiation zones.

Analysis of high temperature and strain amplitude effects on low cycle fatigue behavior of pitting corroded killed E350 BR structural steel

High-tension structural steels are prone to accelerated fatigue damage from pitting corrosion and high-temperature. Despite adverse effects, research on their low cycle fatigue (LCF) behavior is limited. Specifically, studies analyzing temperature-dependent pit sensitivity effects, considering pit-related material’s susceptibility to surface topographic features variation and stress concentration are lacking. This study conducts LCF tests on pitting corroded killed E350 BR structural steel at multiple strain amplitudes and high temperatures. It develops temperature-dependent parameters, such as the cyclic softening pit sensitivity factor, suitable for integration into existing approaches like total cyclic plastic strain energy density (CPSED), power-law, average strain energy density (SED), Coffin-Manson, and pit stress intensity factor (pit-SIF). Further, it proposes multiple linear regression-based prediction models relating total CPSED and average SED with strain amplitude and temperature. Corroded specimens show higher plastic deformation and reduced peak stress, fatigue life, and total CPSED compared to uncorroded ones. The developed parameters, integrated with average SED approach, predicts LCF life within an error band of ±1.5, while power-law relationship reduces it to ±1.2. Moreover, pit-SIF approach estimates fatigue life within an error band of ±1.5. The findings provide critical knowledge for enhanced component design, leading to structural safety, performance, and fire resilience.

Review of morphotectonic studies in the East African Rift System: Insights from legacy research to modern advances

The East African Rift System (EARS) is a prime example of continental rifting, characterized by its iconic topographic features, which are significantly shaped by the interplay of tectonic and climatic forces. This review synthesizes past decades of morphotectonic studies (recent studies) on the plateau landscapes of the EARS, focusing particularly on their interiors and margins, and highlights their crucial role in advancing our understanding of landscape evolution. The paper revisits the legacy of geologic research in the EARS and delves into recent morphotectonic studies that quantify the rates and patterns of plateau incision, exhumation, and uplift through advanced thermochronological and topographic analyses. Additionally, the review identifies key unresolved questions, such as the origins of the plateau topography–whether from volcanic activity or mantle plume influence and explores how these plateaus maintained high elevations during the humid Oligocene Epoch without significant incision. The recent work described in this paper alongside legacy perspectives, continues to refine our geological understanding of the EARS, with broader implications for studies worldwide.

Liquefied capsules containing nanogrooved microdiscs and umbilical cord-derived cells for bone tissue engineering.

Surface topography has been shown to influence cell behavior and direct stromal cell differentiation into distinct lineages. Whereas this phenomenon has been verified in two-dimensional cultures, there is an urgent need for a thorough investigation of topography's role within a three-dimensional (3D) environment, as it better replicates the natural cellular environment. A co-culture of Wharton's jelly-derived mesenchymal stem/stromal cells (WJ-MSCs) and human umbilical vein endothelial cells (HUVECs) was encapsulated in a 3D system consisting of a permselective liquefied environment containing freely dispersed spherical microparticles (spheres) or nanogrooved microdiscs (microdiscs). Microdiscs presenting 358 ± 23 nm grooves and 944 ± 49 nm ridges were produced via nanoimprinting of spherical polycaprolactone microparticles between water-soluble polyvinyl alcohol counter molds of nanogrooved templates. Spheres and microdiscs were cultured in vitro with umbilical cord-derived cells in a basal or osteogenic medium within liquefied capsules for 21 days. WJ-MSCs and HUVECs were successfully encapsulated within liquefied capsules containing spheres and microdiscs, ensuring high cellular viability. Results show an enhanced osteogenic differentiation in microdiscs compared to spheres, even in basal medium, evidenced by alkaline phosphatase activity and osteopontin expression. This work suggests that the topographical features present in microdiscs induce the osteogenic differentiation of adhered WJ-MSCs along the contact guidance, without additional differentiation factors. The developed 3D bioencapsulation system comprising topographical features might be suitable for bone tissue engineering approaches with minimum in vitro manipulation.

Application of Mobile App for On-Site Geoid and Orthometric Height Determination

Determining the vertical component is an essential step. However, due to the exact elevations in relation to a reference surface (e.g., mean sea level), obtaining it is expensive and technically difficult. Through the integration of mobile app technology for surveying and geodetic applications, this research investigated a novel way to on-site geoid calculation. The study, which was carried out in Port Harcourt, Lagos, and Bauchi, effectively created a mobile application utilizing the EGM2008 model and showed that it was more accurate than previous models at capturing geoid and orthometric heights. Despite some non-linear variances brought on by topographical characteristics, the app demonstrated a good correlation between app-generated and observed orthometric heights. In particular, the EGM08 model app routinely beat the SATLEVEL (MAE = 0.011983 in Port Harcourt and 0.060568 in Lagos) and 7-parameters models (MAE = 0.584951 in Port Harcourt and 2.140581 in Lagos). The study concluded that this integrated approach could revolutionize geodetic fieldwork by giving surveyors precise and dependable tools. It also suggests practical implementation, collaboration, and ongoing testing.

Conceptual Modflow Model Application with Boundary Condition Analysis

In this study, groundwater flow modeling of the aquifer in the Porsuk Basin, located in the Eskisehir province of Turkey, was conducted using the MODFLOW modeling method and the Groundwater Modeling System (GMS) software interface. The modeling was performed using the finite difference method under the assumption of steady flow, incorporating well data, aquifer boundaries, topographic elevations, riverbed data, and hydraulic parameters from the 1971 water year. This study provided insights into changes in groundwater over time and yielded a comprehensive water budget. By creating a three-dimensional solid model of the Porsuk Basin aquifer, general information about the region's hydrogeology was obtained. The results are expected to play a significant role in identifying potential drilling areas for groundwater extraction. Since the modeling utilizes objects from geographic information systems, it will enhance visualization of the regional structure for researchers, allowing them to observe the topographic features of the area in three dimensions. Additionally, it is anticipated that the groundwater conceptual model will inform drilling studies and serve as a foundation for research on groundwater transport and pollution.

Mapping Geospatial AI Flood Risk in National Road Networks

Previous studies have utilized machine learning algorithms that incorporate topographic and geological characteristics to model flood susceptibility, resulting in comprehensive flood maps. This study introduces an innovative integration of geospatial artificial intelligence for hazard mapping to assess flood risks on road networks within Portuguese municipalities. Additionally, it incorporates OpenStreetMap’s road network data to study vulnerability, offering a descriptive statistical interpretation. Through spatial overlay techniques, road segments are evaluated for flood risk based on their proximity to identified hazard zones. This method facilitates the detailed mapping of flood-impacted road networks, providing essential insights for infrastructure planning, emergency preparedness, and mitigation strategies. The study emphasizes the importance of integrating geospatial analysis tools with open data to enhance the resilience of critical infrastructure against natural hazards. The resulting maps are instrumental for understanding the impact of floods on transportation infrastructures and aiding informed decision-making for policymakers, the insurance industry, and road infrastructure asset managers.

Macroscopic and Microscopic Development of the Stomach in Hamdani Crossbred Sheep Fetuses (Ovis aries)

The ruminant stomach is a critical digestive department in terms of converting low-quality feed into high nutrient-value substances. In these animals, there is a compound stomach structure with 4 compartments. Understanding the developmental structure of the stomach at macroscopic and microscopic levels is especially important in terms of nutrition. Türkiye can be considered one of the leading countries in the world in terms of sheep breeding. Our study aimed to investigate macroscopically and microscopically the developmental structures of the stomach of Hamdani crossbred sheep fetuses collected at different gestation periods. For this purpose, a total of 15 fetuses, 5 fetuses each from 3 different periods of pregnancy, were included in the study. The stomachs of the fetuses were dissected simultaneously and their topographic and macroscopic features were determined. After routine histological procedures, the stomachs separated from the body cavities were stained with Hematoxylin & Eosin and Masson Trichrome stains. As a result of the study, macroscopic and microscopic information about fetal development of the stomach was obtained. It was revealed macroscopically and microscopically that the rumen was the largest part of the stomach until the middle of the 2nd period of gestation, and that the abomasum grew rapidly at the end of this period and showed similar characteristics to the adult sheep stomach. The data of the study will contribute to macroscopic, microscopic, and ultrasonographic studies on the stomach in ruminant animals.

Investigation of the Relationship between Topographic and Forest Stand Characteristics Using Aerial Laser Scanning and Field Survey Data

The article thoroughly investigates the relationships between terrain features and tree measurements derived from aerial laser scanning (ALS) data and field surveys in a 1067-hectare forested area. A digital elevation model (DEM) was generated from ALS data, which was then used to derive additional layers such as slope, aspect, topographic position index (TPI), and landforms. The authors developed a mathematical procedure to determine the radii for the topographic position index. The canopy height model was created, and individual trees were segmented using a novel voxel aggregation method, allowing for the calculation of tree height and crown size. Accuracy assessments were conducted between ALS-derived data and field-collected data. Terrain variability within each forest unit was evaluated using characteristics such as standard deviation, entropy, and frequency. The relationships between tree height and the derived topographic features within forest subcompartments, as well as the correlation between the height yield map for the entire area and the TPI layer, were analysed. The authors found strong correlation between the topographic position index and tree heights in both cases. The presented remote-sensing-based methodology and the results can be effectively used in digital forest site mapping, complemented by field sampling and laboratory soil analyses, and, as final goal, in carbon stock assessment.