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Flexural Properties in Edgewise Bending of LVL Reinforced with Woven Carbon Fibers
No full textThis paper presents the results of experimental testing of the bending strength and modulus of elasticity in edgewise bending of unreinforced and reinforced seven-layer LVL (laminated veneer lumber) poplar veneer panels. The aim of the research is to determine the influence of woven carbon fibers on the improvement of the bending properties and modulus of elasticity of LVL bending in the plane of the plate, as well as the influence of adhesives on the bending properties of the composite product, in order to test the potential of using this newly obtained material as a structural element. Bending was performed on small-scale samples. The main research task is the examination of three types of reinforcement, which differ from each other in position, orientation, and number of layers of reinforcement, using two different types of adhesives: epoxy adhesive and Melamine Urea Formaldehyde Resins (MUF). The composite material was produced in four different combinations in relation to the orientation and position of the reinforcement in the layup. The applied reinforcement is defined through three different configurations (EK1, EK2, and EK3) and a fourth control sample (EK4). Each configuration was produced by applying the two previously mentioned types of adhesives. The research findings showed that in the case of samples produced by applying CFRP (carbon fiber reinforced polymer) using epoxy adhesive, it significantly affected the increase in bending strength and flexural modulus of elasticity. The average improvement in bending strength is 32.9%, 33.2%, and 38.7%, i.e., the flexural modulus of elasticity is 54.1%, 50.7%, and 54.7%, respectively, for configurations EK1, EK2, and EK3, compared to control sample EK4. During the testing, the test samples from reinforced panels EK1 and EK2 showed partly plastic behavior up to the fracture point, while the diagram for the test samples from reinforced panels EK3 shows elastic behavior to a considerable extent, with a significantly smaller plastic behavior zone. This research proved the impossibility of using melamine-urea formaldehyde adhesive to form a composite product based on veneer and carbon fabric. The greatest contribution of this work is the experimentally verified and confirmed result of the possibility of applying poplar veneer to design structural elements in LVL using epoxy adhesive
Key drivers affecting the spatial heterogeneity of the regeneration process in old-growth beech forests in southeastern Europe
No full textUnderstanding the processes occurring in old-growth forests and identifying their key aspects can significantly enrich modern forestry practices with innovative ideas and concepts. The natural regeneration process in beech old-growth forests exhibits distinct spatial heterogeneity and temporal variability. To define the key drivers that influence the spatial heterogeneity of regeneration processes and their effects, research was conducted in three beech old-growth forests situated in Serbia, Southeastern Europe: Feljesana, Vinatova & ccaron;a, and Kukavica. In each old-growth forest, a network of circular sample plots with an area of 0.1 ha (totaling 45 plots) was established to gather data on structural characteristics and ecological conditions. Within each circular sample plot, data on the regeneration layer were collected on four square sample plots of 1 m2 (180 in total). Using linear mixed models, the key drivers of spatial heterogeneity of regeneration processes in beech old-growth forests were analyzed. Based on the results, several key factors contribute to the highly heterogeneous distribution of seedlings, including the canopy, the presence of a middle layer comprising young trees, ground vegetation, and soil stoniness, while a significant influence of the combined effect of the canopy and the presence of a middle layer of young trees is also defined. The spatial heterogeneity of the regeneration process is also represented through the assessment of the ratio between the abundance of one-year-old and older seedlings. The dominance of one-year-old seedlings intensifies with increased canopy density (in instances of very dense canopy (1.0), the ratio of one-year-old and older seedlings is 70:30%). Seedling growth characteristics are shaped by multiple factors, including the influence of the canopy, the presence of the middle layer of young trees, slope, and soil stoniness, with a substantial combined influence of the canopy and the middle layer of young trees. This indicates that the spatial variability of the regeneration process in beech old-growth forests is primarily driven by factors with a substantial individual influence, which may also act combined. It is of paramount importance to understand these factors and determine their influence on the regeneration process in managed beech forests
Environmental sensitivity assessment and land degradation in southeastern Serbia: application of modified MEDALUS model
No full textThis paper aims to improve the methodology and results accuracy of MEDALUS model for assessing land degradation sensitivity through the application of different data detail levels and by introducing the application of Ellenberg indices in metrics related to vegetation drought sensitivity assessment. For that purpose, the MEDALUS model was applied at 2 levels of detail. Level I (municipality level) implied the use of available large-scale databases and level II (watershed) contains more detailed information about vegetation used in the calculation of the VQI and MQI factors (Fig. S6). The comparison was made using data based on CORINE Land Cover (2012) and forest inventory data, complemented with object-based classification. Results showed that data based on forest inventory data with the application of Ellenberg's indices and object-based classification have one class more, critical (C1 and C2) and that the percentage distribution of classes is different in both quantitative (area size of class sensitivity) and qualitative (aggregation and dispersion of sensitivity classes). The use of data from Forest Management Plans and the application of Ellenberg's indices affect the quality of the results and find its application in the model, especially if these results are used for monitoring and land area management on fine scales. Remote sensed data images (Sentinel-2B) were introduced into the methodology as a very important environmental monitoring tool and model results validation
Phenological Flowering Patterns of Woody Plants in the Function of Landscape Design: Case Study Belgrade
No full textThe study focuses on describing key events in the flowering phenophases of woody taxa that promote practical landscape sustainability and design planning. Apart from the beginning of flowering, the full development and the duration of phenophases are important for landscape architecture, consumers, and pollination. The phenological patterns of 13 woody taxa were monitored for 16 years through 90,860 phenological observations from the BBCH scale for the period 2007-2022. Growing degree days were determined by combining phenological and climatic data and a linear trend was used to assess phenophase tendencies. Mann-Kendall and Sen's slope tests and Spearman's correlation coefficient were used to assess statistical significance. Shifts in flowering indicated warming trends, reflecting various changes in phenology. Early flowering taxa were affected the most, but plants shifted phenophases in both directions (earlier and later in the year). Repeated flowering (and occasionally fruiting) and even third flowering, as seen in 2022, can significantly affect biodiversity and lead to plant-pollinator asynchrony and changes in ecosystem functioning, ecological interaction, and landscape design. A list of native and introduced taxa and their adaptation mechanisms to climate change are provided and can be used for sustainable landscape design and nature-based solutions in landscape architecture
Environmental and Health Risk Assessment Due to Potentially Toxic Elements in Soil near Former Antimony Mine in Western Serbia
No full textBackground: Anthropogenic activities have clearly affected the environment, with irreversible and destructive consequences. Mining activities have a significant negative impact, primarily on soil, and then on human health. The negative impact of the first mining activities is represented even today in the soils of those localities. Research shows that, for different types of mines, the concentrations of potentially toxic elements (PTEs) are high, especially in antimony, multi-metal and lead-zinc mines, which have adverse effects on the environment and then on human health and the economy. A large flood in 2014 in Western Serbia resulted in the breaking of the dam of the processed antimony ore dump of the former antimony mine, causing toxic tailings to spill and pollute the downstream area. Due to this accident, tailings material flooded the area downstream of the dump, and severely affected the local agriculture and population. Methods: Potentially toxic elements content, pollution indices and health indices were determined in soil samples from the flooded area, using referenced methodologies. The sources and routes of pollutants and risks were determined and quantified using statistical principal component analysis, positive matrix factorisation, and a Monte Carlo simulation. Results: The main source of As, Cd, Hg, Pb, Sb and Zn in the upper part of the study area was the tailing material. Based on the pollution indices, about 72% of the studied samples show a high risk of contamination and are mainly distributed immediately downstream of the tailings dump that was spilled due to heavy rainfall. Conclusions: Although the content of the PTEs is high, there is no non-carcinogenic risk for any PTEs except As, for which a threshold risk was determined. There is no carcinogenic risk in the study area
Design proposal development for a more liveable open public space
No full textAs a vital element of successful cities, public spaces play an important role in achieving sustainable development goals. The New urban agenda considers public spaces as a need in sustaining the productivity of cities, eco-social cohesion and inclusion, civic identity, and quality of urban life. This is also in line with the New European Bauhaus, as a part of European Green Deal, need to create beautiful places, practices and experiences that are enriching, sustainable and inclusive. In accordance with that there is undoubted importance of the public spaces, while its quality is generated in the symbiosis of various elements. On the basis of normative theories in urban design, SCORELINE framework for public space quality evaluation was developed and tested at the research group for planning and design in landscape architecture at the University of Belgrade - Faculty of Forestry. The framework covers six criteria which illuminate key aspects of public spaces such as safety and security, convenience, legibility, comfort, inspiration and sensitivity and liveability. For the purpose of this research, special attention is given to the criteria of liveability. It will be presented through its quantitative and qualitative indicators and its application in practice that cover the investigation carried out on Cara Urosa Street within the Lower Dorcol quarter in Belgrade, Serbia. The results of this analysis defined the inputs for street renewal design proposal, that was additionally tested using Space Syntax method, precisely Depthmap X simulation software to map potential issues and potentials that will be developed through design in order to achieve the defined goals concerning the liveability of open public space
Seiridium cardinalale - a new pathogen on ornamental cypress plants in Serbia
No full textČempres (Cupressus sempervirens L.) je vredna ukrasna biljka koja se, kao ni u
većini Evropskih zemalja ne javlja prirodno u Srbiji (Jovanović 1971). Najbliža prirodna
staništa čempresa su grčka ostrva Krit, Karpatos, Kos, Kalimnos, Rodos, Samos i Turska
(Farjon & Filer 2013). Međutim, zbog velike estetske i ekološke vrednosti ova vrsta je
intenzivno unošena u prošlosti tako da je naturalizovana u većem delu mediteranskog
basena. U Srbiji se proizvodi u rasadnicima ili uvozi iz inostranstva i koristi kao ukrasna
vrsta. Razvoj čempresa najviše ugrožava patogena gljiva Seiridium cardinale (Wagener)
Sutton & Gibson, koja nanosi ogromne ekološke i ekonomske štete u Kaliforniji i na
Mediteranu (Danti & Della Rocca 2017). Seiridium cardinale je invazivna vrsta iz familije
Sporocadaceae (Bonthond et al. 2018), a pored čempresa kao glavnog domaćina osetljive su
i druge srodne vrste iz familije Cupressaceae. Propadanje čempresa primećeno je u jesen
2014. u urbanoj zoni Beograda. Nakon sprovedenih istraživanja, na osnovu jedinstvene
kombinacije domaćina, simptoma, izgleda kolonije, plodonosnih tela i spora,
identifikovana je patgena gljiva S. cardinale, što je bio i njen prvi nalaz u Srbiji (Milijašević
2003; Milenković et al. 2022). Glavni simptomi su uvenuće četina, dok su na deblu i
granama prisutne rak rane uz obilan izliv smole. Plodonosna tela – acervule se javljaju na
kori debla i grana, kao i na šišaricama. Acervule obrazuju brojne konidije specifičnog
izgleda, koje su vretenaste, šestoćelijske (sa pet pregrada), gde su dve spoljašnje ćelije
bezbojne, a četiri unutrašnje smeđe. Dimenzije konidija su 25 × 9 µm, a prisutni su i jedva
primetni privesci. Kasnijim istraživanjima ova patogena gljiva je zabeležena i u drugim
urbanim sredinama u Srbiji, gde je izazvala propadanje stabala različite starosti i
dimenzija.
Seiridium cardinale je u Srbiju najverovatnije dospeo putem zaraženog sadnog
materijala. Pored čempresa, ovaj patogen predstavlja veliki rizik za industriju rasadničke
proizvodnje niskih četinara iz rodova Chamaecyparis, Cryptomeria, Juniperus, Thuja i
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×Cupressocyparis, kao i za ukrasne zasade ovih vrsta. Uzimajući u obzir da su ove vrste
široko zastupljene u rasadničkoj proizvodnji i na zelenim površinama u Srbiji, potrebno
je sprovesti detaljni monitoring naših rasadnika i urbanih zelenih površina, kako bi se na
vreme ustanovilo prisustvo patogene gljive S. cardinaleCypress (Cupressus sempervirens L.) is a valuable ornamental plant that, like in
most European countries, does not occur naturally in Serbia (Jovanović 1971). The closest
natural habitats of cypress are the Greek islands of Crete, Carpathos, Kos, Kalimnos,
Rhodes, Samos and Turkey (Farjon & Filer 2013). However, due to its great aesthetic and
ecological value, this species was intensively introduced in the past, so it was naturalized
in most of the Mediterranean basin. In Serbia, it is produced in nurseries or imported from
abroad and used as an ornamental species. The development of cypress is most
threatened by the pathogenic fungus Seiridium cardinale (Wagener) Sutton & Gibson,
which causes enormous ecological and economic damage in California and the
Mediterranean (Danti & Della Rocca 2017). Seiridium cardinale is an invasive species
from the family Sporocadaceae (Bonthond et al.), and in addition to cypress as the main
host, other related species from the Cupressaceae family are also sensitive to it. Cypress
decay was observed in the autumn of 2014 in the urban zone of Belgrade. After a
conducted research, on the basis of a unique combination of the host, symptoms, and
appearance of the colony, fruiting bodies and spores, the pathogenous fungi S. cardinal
was identified, which was its first finding in Serbia (Milijašević 2003; Milenković et
al.2022). The main symptoms are withered needles, while on the trunk and branches there
are canker wounds with an abundant outflow of resin. Fruiting bodies – acervuli occur
on the bark of the trunk and branches, as well as on cones. Acervuli form a number of
conidia of a specific appearance, which are spindle-shaped, six-cell (with five partitions),
where two outer cells are colorless, and four inner cells are brown. The dimensions of the
conidium are 25 × 9 µm, and barely noticeable pendants are also present.
Later research recorded this pathogenous fungi in other urban areas of Serbia,
where it caused deterioration of stems of different ages and dimensions.
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Seiridium cardinale was probably introduced to Serbia through infected planting
stock. In addition to being a threat to cypress, this pathogen is a great threat to the
industry of nursery production of small conifers from the genuses Chamaecyparis,
Cryptomeria, Juniperus, Thuja and Cupressocyparis, as well as for the ornamental plantings
of these species. Taking into account that these species are widely represented in nursery
production and on green spaces in Serbia, it is necessary to carry out detailed monitoring
of our nurseries and urban green spaces, in order to recognize the presence of the
pathogenic S. cardinale fungi in due tim
Investigating plant stress through nondestructive optical methods
No full textPodaci o optičkim karakteristikama listova dobijeni spektrofotomertijskim
metodama mogu da nam donesu korisne informacije o trenutnom stanju i zdravlju
biljaka. U literaturi su već poznati sistemi koji se bave izučavanjem spektoskopskih
karakteristika lista. Uz pomoć nove nedestruktivne optičke metode merenjem vrednosti
optičke transmisije i optičke refleksije lista, indirektno se mogu dobiti vrednosti apsorbcije
svetlosti lista biljke. Kako je opšte stanje biljke u direktnoj vezi sa fotosintetičkim
procesima koji se odvijaju u listovima, navedena metoda na osnovu oblika funkcije
cirkadijumskog ritma posmatranih biljaka, može da detektuje stres biljaka izazvan
različitim izvorima stresa. Metoda je testirana na sledećim biljnim vrstama: Ocimum
basilicum (biljke su gajene hidroponski); Phaselolus vulgaris i Zea mays (semena su rasla u
komercijalnom humusu), Guzmania lingulata, Vriesea carinata, Tillandsia brachycaulos,
Ananas comosus, Kalanchoe daigremontiana, Capsicum annuum, Tillandsia xerographica, Carya
illinoinensis, Juglans ailantifolia var. cordiformis (biljke su rasle u komercijalnom humusu).
Pokazalo se da metoda može da ukaže na prisustvo različitih vrsta stresa, a to su potvrdili
rezultati testova na: nutritivni stres, stres izazvan herbicidom, stres izazvan vodnim
deficitom i stres izazvan jakim svetlom. Predstavljena metoda je prošla nekoliko faza
verifikacije, a ideja je da se primeni na još veći spektar biljnih vrsta i da se uspostavi
korelacija sa vrednostima drugih parametara dobijenim starim, tradicionalnim,
destruktivnim metodama.The measurement of leaf optical characteristics through spectrophotometric
methods can provide valuable insights into the health and current state of plants. The
examination of leaves' spectroscopic characteristics has been documented in previous
literature. The utilization of a novel non-invasive optical method, which involves the
collection of leaf optical transmission and reflection values, allows for the indirect
determination of light absorption in plant leaves. Given that the overall state of the plant
is closely linked to photosynthetic processes taking place within the leaves, this method,
based on the circadian rhythm function observed in plants, can detect plant stress
resulting from various stressors. The method was tested on various plant species,
including Ocimum basilicum (hydroponically grown), Phaselolus vulgaris and Zea mays
(seeds grown in commercial humus), Guzmania lingulata, Vriesea carinata, Tillandsia
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brachycaulos, Ananas comosus, Kalanchoe daigremontiana, Capsicum annuum, Tillandsia
xerographica, Carya illinoinensis, and Juglans ailantifolia var. cordiformis (plants grown in
commercial humus). The results showed the method's ability to detect different types of
stress, including nutritional stress, herbicide-induced stress, water deficit-induced stress,
and stress caused by intense light. The proposed method has undergone multiple
validation phases and the aim is to apply it to a wider range of plant species and correlate
the results with those obtained through traditional, destructive metho
Forest reclamation in function of improving the forest fund
No full textDegradacija šumskih ekosistema, zajedno sa klimatskim promjenama, predstavlja jedan od najznačajnijih problema današnjice.Posljednje procjene ukazuju da je više od 2 milijarde hektara šuma u svijetu degradirano, pri čemu je očekivana tendencija njihove dalje degradacije usljed povećanih pritisaka na šumske ekosisteme. Melioracije degradiranih šuma oslanjajusena osnovne principe teorije i prakse gajenja šuma, predstavljaju veoma kompleksne procese i zahtijevaju specifičan uzgojni pristup koji podrazumijeva primjenukomplikovanih i često finansijski zahtjevnih metoda u cilju postizanja zadovoljavajućih rezultata. Veliki značaj melioracije degradiranih šuma ogledaseu njihovom potencijalu za obezbjeđivanje održivosti šumskih ekosistema, očuvanje i povećanje biodiverziteta, unapređenje funkcija šumskih ekosistema, kao i ublažavanje globalnih klimatskih promjena.Adaptivno upravljanjei melioracija degradiranih šuma su osnovninačini za kritične strategije usmjerenena povećanje funkcionalnosti i stabilnosti šuma pod višestrukim pritiscima globalnih promjen
A contribution to the knowledge of fungi Daedaleopsis confragosa (Bolton) Schröt the cause of white rot of hardwood
No full textU okviru roda Daedaleopsis je opisano šest vrsta, mada neki izvori navode 10(11) vrsta. U Evropi se javljaju dve vrste D. confragosa (sa varijetetom tricolor) i D. septentrionalis. Daedaleopsis confragosa prouzrokuje belu trulež lišćara i najčešće se javlja kao saprotrof, a ređe i na živim stablima kao fakultativni parazit. Plodonosna tela D. confragosa obrazuju dva tipa himenofora i pokazuju razliku u boji površine šešira. Na osnovu ovoga su u prošlosti izdvojene dve vrste D. confragosa sa poroidnim himenoforom i D. tricolor čiji je himenofor izgrađen iz lamela. Ciljevi ovog rada su bili da se izvrši izolacija gljive iz morfološki različitih plodonosnih tela i da se utvrdi da li ima razlike u porastu i izgledu čistih kultura. Utvrđeno je da su reakcije i porast na podlogama sa dodatkom galne, odnosno taninske kiseline iste, a nisu zabeležene značajne razlike u porastu na različitim temperaturama. U nekim slučajevima su na grani trešnje na kratkoj distanci obrazovana oba tipa plodonosnih tela, a posle izolacije su dobijene morfološki identične kulture. Na osnovu ovih rezultata i ranije sprovedenih molekularnih istraživanja, smatramo da nema opravdanja da se D. tricolor smatra čak i kao varijetet i da se radi o jednoj vrsti D. confragosa. Gljiva D. confragosa ima lekovita svojstva i pokazuje: citotoksično, analgetsko, antikancerogeno, antigljivično, antibakterijsko i antivirusno dejstvo