Omorika Digital repository of the Faculty of Forestry, University of Belgrad
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Photometric analysis of an X-ray image
No full textPrevious research demonstrated a link between wood strength and brightness intensity in X-ray images. This was achieved by testing wood samples under compressive forces applied along and across
the grain, with X-ray imaging conducted on the same samples prior to the compression tests. Differences in the brightness of X-ray images of test specimens were clearly noticeable, both in relation
to the type of sampled wood and depending on the specifi c alignment of X-ray beams relative to the
direction of wood fi bers in the test specimen.
Since wood is an orthotropic and heterotropic material, and such fi ndings were hypothetically expected, the fi nal phase of establishing a non-invasive X-ray method for testing the mechanical properties
of wood could be approached. This phase involves the numerical determination of the brightness intensity of X-ray images, thereby opening the possibility of correlating mechanical strength parameters
of the sampled wood with the brightness parameters of its X-ray images. OsiriX is a software program
that could facilitate this achievement. Given its capability for numerical analysis of light effects, it is
plausible that its measurement scale could also be expressed in pixels.
Because wood has an anisotropic structural composition, it is expected that the X-ray image of the
tested sample would exhibit uneven brightness. Photometric analysis of the X-ray image using computer software allows for assigning appropriate mechanical properties to each point on the image via x, y, v parameters. However, since an individual light point cannot represent the cumulative mechanical properties of the sampled test specimen, it is clear that the task at hand also includes the
need for homogenizing the X-ray image. This is achievable through the program’s three-dimensional
approximation capabilities.
The formation of a tonal gray scale achieved through homogenization would lead to the equalization
of the mechanical and brightness parameters of the sampled wood’s strength, as a resultant of the
cumulative sum of its mechanical potential
Research of ecological conditions of specialpurpose forest to assess the environmental state of the Belgrade agglomeration
No full textThe paper covers research in the fields of urban forestry and environmental ecology.
The research results on ecological factors in forest habitats in the periurban zone of
Belgrade are presented. The studied complex is classified into forests with a priority
protective function and forests intended for recreation and cultural functions. The
paper aims to assess the ecological potential of habitats in relation to the purpose and
ecosystem services of forests. Based on the research results, it will be possible to
reconstruct parts of the forest complex that are underutilizing the habitat's potential.
The climate character was determined based on the climate index using the
Thornthwaite method. Based on air temperatures and precipitation amounts (2002-
2016), the soil moisture deficit and surplus, potential and actual evapotranspiration,
aridity and humidity indices, and the climate index were calculated. The habitat is
characterized as: a habitat of submontane beech forest (Fagetum submontanum) on
eutric brown soil on loamy sediments; a habitat of Hungarian and Turkey oak forest
with manna ash (Quercetum frainetto-cerridis ornetosum) on eutric brown soil on loamy
sediments, and a habitat of a typical Hungarian and Turkey oak forest (Quercetum
frainetto-cerridis typicum) on illimerized eutric brown soil on loamy sediments. The
objective of management is to develop silvicultural measures that facilitate the
regeneration of introduced tree species
Biodiversity, Heritage and Ecosystem Service Potential of Woody Taxa in Scattered Built Environments of Traditional Agricultural Landscapes
No full textAgricultural landscapes often exhibit low tree cover and homogeneity, leading to various
environmental challenges. Traditional farmsteads, as scattered built environments in agricultural landscapes with diverse woody vegetation, enhance ecological heterogeneity and
provide significant ecosystem services (ES), yet their dendroflora remains understudied.
This study assesses woody vegetation on ten traditional farmsteads in Vojvodina, Serbia
as case studies, through field surveys of woody species, biodiversity indices, GIS-based
spatial analyses, and classification of species according to functional and ecosystem-related
traits, offering insights into ecological patterns within these landscapes. The analysis examines species composition, abundance, origin, structural traits (tree cover, density, age,
height, and crown width), and functional roles in ES provision. The vegetation shows
potential to contribute to ES, especially through melliferous species (about 80%), food
sources (about 82% for humans; 91% for birds, 91% for small mammals, 87% for domestic
animals), and windbreak functions (about 76%). Phytoncide-producing species (about
62%) suggest a potential provision of air quality benefits, while entomophilous species
(about 83%) indicate a potential provision of pollination support. Traditional farmsteads
support biodiversity conservation, habitat provision, and preservation of genetic resources,
particularly through old and rare species. Integrating these systems into agroforestry
and biodiversity-friendly practices may increase ecological resilience and balance in intensive farming areas. Recognising traditional farmsteads as biodiversity reservoirs is
vital for sustainable land use, and for conserving cultural and natural heritage within
agricultural landscape
Trachelospermum jasminoides (Lindl.) Lem. in pergola design: An experimental study in Belgrade
No full textThe paper analyzes the potential application of Star Jasmine, a climbing plant
from the subtropical biome, in pergola design in Belgrade, considering the growing
interest in the phenomenon of urban heat islands as a result of increased
urbanization, improper planning, and design. In order to understand this
phenomenon, the integration of meteorological components into the design process
and the appropriate selection of plants in landscape design is encouraged. Therefore,
comprehensive analyses of climatic parameters, phenological, and morphological
characteristics during the period from 2015 to 2024 confirmed the adaptability of the
species on a pergola in a private garden in the Čukarica district of Belgrade. It is
particularly notable that Star Jasmine, at the age of two, tolerated severe frosts in a
protected position from the dominant cold northwestern and southeastern winds. The
morphometric characteristics of the leaves were within the expected range, while the
dimensions of the flowers exceeded the values cited in the literature for Star Jasmine
in the Northern Hemisphere. For the first time, the number of flowers in the
inflorescences and the number of pistils in the flowers were determined. The
obtained results are significant considering that Star Jasmine is an evergreen species
with a fine texture, has a long flowering phenophase, and that there are only few
woody climbing plants with such characteristics in Belgrade. Further research is
necessary to define guidelines for pergola design, in the context of climate change.
In urban environments ornamental climbing plants provide year-round value and
require minimal maintenance
The influence of the number of cabinet connector fittings on the durability of cabinet furniture – a case study
No full textThis paper shows the influence of the quality of the chipboard on the number of fittings (cabinet
connectors) per connection line. In order to reduce transportation costs, cabinet furniture is in most
cases made as knock-down furniture by applaying excenter connecting fitting. The number of fittings
per connection line in most cases depends on the depth of the cabinet, as well as on the quality of the
chipboard. The strength of the board against delamination is the main property of the board that will
affect the number of connection elements. The test was carried out on cabinets taken from regular
production, which belong to the lowest price group of cabinet furniture. The static analysis showed
that there is a significant influence of the number of fittings on the rigidity and durability of cabinet
furniture. Variation in the number of fittings leads to changes in the rigidity and durability of the tested
furniture.
The results of this research proved that during the prosess of constructing furniture from the
lowest price group, the construction rules should be take with caution into consideration. The paper
gives recommendations regarding the number of connection elements per connection line
Divergent Trends in Insect Disturbance Across Europe's Temperate and Boreal Forests
No full textOngoing shifts in climate and land use have altered interactions between trees and insect herbivores, changing biotic disturbance
regimes. However, as these changes are complex and vary across host species, insect taxa, and feeding guilds, they remain poorly
understood. We compiled annual records of forest insect disturbance from 15 countries in temperate and boreal Europe, spanning
the period from 2000 to 2022. The dataset comprises 1361 time series characterizing the dynamics of 50 herbivorous insects.
We used this dataset to test whether insect disturbance has systematically changed during the 23-year
period across host trees
and feeding guilds, whether it varies along latitudinal and climatic gradients, and whether synchrony exists among species in the
same guild or among species sharing the same host. Since 2000, borer disturbance was predominantly concentrated on gymnosperms,
while defoliators impacted gymnosperms and angiosperms more evenly. While 85.8% of gymnosperm disturbance was
inflicted by a single species, Ips typographus, the majority of disturbances to angiosperms were caused by six different species.
Borer impact on gymnosperms has increased in the 21st century, while defoliator impact has decreased across both clades.
In contrast to diverging temporal trends, disturbance was consistently greater in warmer and drier conditions across feeding
guilds and host types. We identified significant synchrony in insect disturbance within host types and feeding guilds but not
between these groups, suggesting shared drivers within guilds and host types. Increasing insect disturbance to gymnosperms
may catalyze adaptive transformations in Europe's forests, promoting a shift from historical conifer-dominated
management
to broadleaved trees, which are less affected by insect herbivores. Our findings reveal a diversity of trends in insect herbivory,
underscoring the need to strengthen monitoring and research in order to better understand underlying mechanisms and identify
emerging threats that may not be apparent in currently available data
Bioherbicidal Evaluation of Methanol Extract of Sorghum halepense L. Rhizome and Its Bioactive Components Against Selected Weed Species
No full textSorghum halepense (L.) Pers. (common name Johnson grass) is a perennial invasive weed that causes great harm worldwide, and its allelopathy has been demonstrated in a series of experiments. The present study offers new insights into its organ-specific phytochemical profiles using state-of-the-art metabolomic technology and explores the effects of a methanol extract of S. halepense rhizomes (ShER) and its major bioactive compounds (p-hydroxybenzoic acid and chlorogenic acid) on three noxious weed species. The phytotoxic effects of ShER are reflected through the inhibition of seed germination and reduced seedling growth, which are accompanied by changes in the antioxidant system of seedlings. Phytotoxicity is species specific and concentration dependent, and it is more pronounced against Chenopodiastrum murale (L.) S. Fuentes, Uotila & Borsch and Datura stramonium L. than highly tolerant Amaranthus retroflexus L. Catalase (CAT) is most likely the major mediator in the removal of reactive oxygen species, which are generated during germination and early seedling growth of Ch. murale exposed to ShER. The results of the present study imply the high potential of ShER in the management of amaranthaceous and solanaceous weeds, such as Ch. murale and D. stramonium, respectively. The present study offers an environmentally friendly solution for the biological control of weeds belonging to the families Amaranthaceae and Solanaceae. Also, the results of this research highlight the possibility of effective management of S. halepense by using it as a feedstock for bioherbicide production
Development and applications of bioepoxies for green materials
No full textThe growing demand for sustainable materials has intensified research into bio-based
thermosetting polymers as alternatives to conventional petroleum-derived systems. Epoxy resins,
widely used in coatings, adhesives, composites, and electronics, are traditionally synthesized from
fossil resources, raising environmental and health concerns due to their non-renewability and
toxicity. Bioepoxies, derived from renewable feedstocks such as vegetable oils, lignin, and tannins
offer a promising pathway to reduce environmental impact while maintaining key performance
characteristics: tannins provide aromatic structures for high thermal stability and flame resistance;
lignin is abundant and inexpensive, yielding reactive phenolics through depolymerization; while
vegetable oils are cost-effective and easily modified for coatings and adhesives. However, challenges
remain, including the heterogeneity and solubility of tannins, the high viscosity and variable
reactivity of lignin, and the lower mechanical and thermal performance of vegetable oil-based
epoxies. Continued progress in chemical modification and curing strategies will be essential to
improve performance. Overall, bio-based epoxies show strong potential to replace BPA-based resins
and contribute to sustainable polymer development
Uticaj temperature i padavina na prirast hrasta kitnjaka na hladnijim staništima područja Đerdapa: prvi rezultati
No full textPrvi rezultati analize uticaja temperature i padavina na prirast hrasta kitnjaka na području Đerdapa istraživani su u dve sastojine hrasta kitnjaka na hladnijim staništima. U analizi ove vrste uticaja na radijalni prirast (RW), prirast kasnog drveta (LW) i prirast ranog drveta (EW) pomenute vrste drveća korišćene su četiri metodološke procedure: 1) korelacije između tromesečnih (sezonskih) veličina temperature i padavina i rezidualne hronologije, 2) korelacije između mesečnih temperatura i padavina i rezidualne hronologije, 3) tzv. odzivne funkcije i 4) korelacije između SPEI3 (integrisanog za 3 meseca) indeksa suše i rezidualne hronologije. Konstatovana je značajna senzitivnost hrasta kitnjaka prema padavinama u letnjim mesecima, na taj način da veće količine padavina u leto, naročito u julu, prouzrokuju statistički značajno veće iznose prirasta i stabla su vitalnija. Značajan uticaj temperature na prirast nije registrovan, osim u slučaju korelacija između sezonskih (3-mesečnih) klimatskih elemenata i ostvarenog prirasta. Kao i u slučaju preliminarnih rezultata analize varijacija iznosa padavina i temperatura na rast kitnjaka na toplijim staništima Đerdapa, utvrđeno je da je u ukupnoj veličini radijalnog prirasta i u prirastu kasnog drveta detektovan jači klimatski signal nego u prirastu ranog drveta. Dobijeni rezultati zvanično su pokazali da je hrast kitnjak na hladnijim staništima značajno više otporan na negativni uticaj natprosečnih temperatura nego u letnjim mesecima na toplijim staništima Đerdapa, utvrđen u ranijim sličnim istraživanja sa područja NP ‘’Đerdap’’
The influence of air temperature and precipitation on the flowering and sustainability of Acer pseudoplatanus L. in the Zvezdara Urban Forest (Belgrade, Serbia)
No full textThe aim of this study is to highlight the importance of Acer pseudoplatanus as a component of urban
forests within the urban heat island zone of Belgrade. Through an integrative approach combining
phenological and climatic elements, and using a case study covering the period from 2007 to 2025,
the influence of air temperature and precipitation on the flowering patterns of this native species
in Serbia was assessed. Based on 5,738 phenological observations over 19 consecutive years, key
flowering elements were identified, which are crucial for pollination, fruiting, and the long−term
sustainability of the species. To investigate the spatio−temporal changes in flowering patterns,
the Mann−Kendall test in conjunction with Sen’s slope estimator and the Spearman Rank test were
applied. To quantify correlations between the studied species parameters and to confirm season−
ality, particularly in comparison with Acer platanoides, circular statistics, along with the Rayleigh
and Watson−Williams tests, were used. The results confirm that A. pseudoplatanus is an adaptive
species under climate change conditions. Findings indicate that key flowering phase shifts in
A. pseudoplatanus are not significantly influenced by climatic variables; rather, the onset, full bloom,
and end of flowering occur within defined thresholds of accumulated heat. However, compared
to the average, the flowering phenophase was extended by 10.4 days in 2024 and by 2.4 days in
2025, although the trends did not reach statistical significance. The visual identity of the
Zvezdara Forest in landscape phenology, as a reflection of climate change through phenological
indicators, is characterised by a strong seasonality in the flowering patterns of sycamore maple
A. pseudoplatanus in mid−spring, preceded by the flowering of A. platanoides in early spring. In con−
clusion, the study highlights the importance of promoting native species in the design of urban
forests, both for their ecosystem services as nectar−producing (pollinator−supporting) species,
and for enabling the development of nature−based solutions that mitigate the effects of urban
heat islands. Their contribution to springtime landscape phenology reinforces the ecological
and aesthetic value of such species in urban environments