Omorika Digital repository of the Faculty of Forestry, University of Belgrad
Not a member yet
2577 research outputs found
Sort by
Soil moisture conditions in spring months in Quercus petreae forests in Fruška gora, AP Vojvodina, Serbia
No full textThe International Cooperative Programme on Assessment and Monitoring of Air Pollution
Effects on Forests (ICP Forests) is the largest international forest monitoring system.
Intensive monitoring (level II) covers 561 plots (as of 2020) in selected forest ecosystems. In
Serbia are established 5 intensive monitoring (level II) plots. The paper will show only data
for Quercetum petreae forests in Fruška Gora, AP Vojvodina, Serbia. In the previous period
an increase in extreme events could be observed in spring months. For the past three years,
temperatures in March have ranged from cold (2022), to normal (2021) and warm (2023).
April was characterized by very cold weather, while May experienced cold (2021) to very
warm weather (2022). Precipitation was normal, except for rainy April 2023, and very dry
March and May 2022. In past 30-year period the trend in temperature increase was recorded
for March and April, and slightly decrease in May (y = -0.0194x + 56.308). On other hand for
the precipitation was recorded trend for increasing in March and April, and slightly increase
in May (y = 1.3894x - 2713.1). Soil moisture content (depth 10 cm, 30 cm and 50 cm) show
statistically significance difference between 2021 and 2023 year from one side and 2022 year
from other side. This difference was most significance on 50 cm depth during last years.
Based on this data we have a trend of increasing of deviation of mean monthly temperature
and precipitation had a statistically significance difference on soil moisture in Querqus
petreae forests
Soil Degradation Indicators as a tool for Climate-Smart Urban Forestry
No full textThe main objective of the project “Urban Forest Soil Indicators as a tool for Climate-Smart Forestry” (UrbanFoS) is to define soil degradation indicators in UF to adapt to and mitigate CC and anthropogenic pressure in urban areas. This goal will be achieved by determining the key sensitivity soil properties through pysico-chemical analyses and climate simulation experiments; and defining ecosystem services (ES) of UF. Defined indicators will be used to test existing soil degradation indices applicable to forest soils and a suitable soil degradation index for UF under CC conditions will be proposed. Finally, based on previous steps, UbranFoS will define restoration measures based on the principle of ecological engineering and Nature-Based Solutions (NBS)
The Influence of Rainfall Simulators Dripper size, Type and Dripping Speed on Generated Drop Size
No full textThe choice of drippers for dripping rainfall simulators (DRS) is often based on the experience of previous research or personal empirical knowledge, under the assumption that drippers in form of tubes and holes with a smaller internal diameter (ID) generate water drops of a smaller diameter and vice versa, neglecting other factors that affect the size of the drops. The aim of research is to provide insight into the influence of DRS dripper size, type and dripping speed (i.e., the number of water drops dripped out from a dripper per unit of time) on generating different water drop size. A search was conducted for all available scientific papers describing DRS and papers that include a wide range of thematically related papers to soil research in which DRS are used starting from 1941 until today. Out of a total of 188 scientific papers included in the analysis, 76 different types and 31 subtypes of DRS have been singled out. The analyses of DRS drippers design and performance was conducted in terms of the drops’ sizes that they are able to generate. The analysis was conducted integrally, for simulators with more than one dripper and with one dripper. Metal and plastic tubes (MT and PT), which are the most common drippers’ type, showed a strong relationship between the outer diameter (OD) with the drop size, while the ID relationship was moderate to weak. However, when increasing the range of MT drippers’ diameter size, the relationship significance became very strong for both ID and OD. It is observed that with the increase of the ID of PT the relationship deviates from the logarithmic curve that represents all dripper types together. Although the applied dripping intensity difference is quite big for MT, drop size does not differ much. On the other hand, PT generate much bigger difference in drop size for a less drastic change in intensity. It is suggested that a possible reason for such a deviation and difference in the functional forms that describes drop and drippers size relations could be the dripper material, but considering that MT drippers generally have a thinner wall than PT or glass tubes (GT), drippers material type rather determines the thickness of the tube wall
Parameter determination and performance comparison of the rheological models for creep in particleboard
No full textA rheological model presents the stress-strain relationship in a material throughout the entire
exploitation period. The change of the properties of a stressed and strained material in the time domain
could be assessed on the basis of the rheological model. This paper focused on the determination of
model parameters and comparison of several rheological models for particleboard coated with
melamine foil. The model parameters were defined for four models: the purely mathematical Powerlaw model (two-parameter), and two viscoelastic models, i.e. the Zener (three-parameter) and Burger
(four-parameter) models, as well as a semi-empirical modified Burger (five-parameter) model. The
performance of models was compared in two ways: (i) according to the fit to the experimental data
and (ii) according to the better total strain prediction. The Power-law and modified Burger models
stood out as the best. The modified Burger model achieved better fitting to the experimental data, and
the Power-law model was slightly better at making predictions
Green infrastructure: The question of efficiency in the renewal of urban form, case study of Serbia
No full textApart from the general problem of the sustainability of the urban
form and its integral part - the urban system of green areas, in relation to global challenges, the paper tries to give a broader application of the theoretical concept of green infrastructure and its
interrelationships within cities. It is considered that the approach
to the application of the concept is always related to a specific
spatial problem and that in this sense the theoretical approach
is adapted to the specifics of the research subject with the assumed goals. To what extent different land uses in the urban landscape can be the bearers of the renewal of the urban form? Also,
whether it is possible to be effective in terms of a quick overview
of the urban structure and the eventual model of the green infrastructure of cities in Serbia, but also beyond?
The approach implies a holistic framework in relation to the diversity of land use in cities as well as the scale of observation from
dominant spatial units to smaller individual areas. The method is
based on the theoretical approaches of Ahern’s Novel Urban Ecosystems and Davies and colleagues who defined the grey-green
continuum. The goal is to deal with the problems with the theoretical and practical aspects of the green infrastructure concept, to
deductively generalize the values for certain uses in order to then,
through the analysis of different cases of several cities in Serbia,
obtain a nuanced overview of the current development of cities in
different regional contexts and what the guidelines could be for
the renewal of the urban form. The work proves the possibility of
an effective display of different uses within the city, but also of
the typology and spatial arrangement of potential elements of the
green infrastructure model for the selected cities
Same Situation Seen Differently: Covid-19 and Teaching/Learning at Agricultural Faculties in Croatia, North Macedonia, Bulgaria, and Serbia
No full textThe aim of this study is to compare the attitudes of teachers
and students from different Higher Education (HE) institutions
about online classes. The online survey has been conducted
with 123 teachers and 362 students from agriculture faculties
in Belgrade (Serbia-UB), Osijek (Croatia-UNIOS), Stara
Zagora (Bulgaria-TrU), and Skopje (North MacedoniaUKIM). Results indicate that teachers and students in our study
were aware that online teaching has its potential and
limitations. Teachers were more positive toward online classes
than students, although they were aware that students cannot
master practical skills. The majority of students believe that
online learning did not contribute to their: learning outcomes
(43%), learning efficiency (50%), communication and
cooperation (52%). Teachers from all HEIs emphasized the
weaker ability to control students' independence in the
examination situation as the most important problem of online
assessment. Teachers and students have different judgments
about the emotional correlates of online learning: among other
aspects, students find that online learning is connected to
loneliness (46%) and depression (32%). The majority of
teachers (80%) disagree that online teaching is a potential risk
to students’ loneliness and depression. Despite the specificity
of the educational context at different universities, students’
perception of online teaching/learning is more similar than
teachers and is generally somewhat more critical. The findings
also point to one typical problem in HE - teachers need to
recognize and respect the student's perspective, regardless of
the medium in which classes were organize
Influence of the covid-19 pandemic on the import and export of chrysanthemums in Serbia
No full textAfter roses, chrysanthemums are the second best-selling cut flowers in FloraHolland which is
considered as the largest market of floricultural products in the world. Chrysanthemums are
also important in the flower production in Serbia, and they are produced both for domestic
and international market. Taking into account that Covid-19 pandemic influenced production
and consumption of cut flowers worldwide, including the chrysanthemums, the aim of this
study was to determine how the pandemic influenced export and import of chrysanthemum
cut flowers in Serbia. For that reason, the trend analysis was used to calculate trends for the
years 2020 and 2021 in order to determine expected change in export and import based on
five years data (2015-2019) collected before the pandemic. Obtained data were compared
with the real data collected for the pandemic years 2020, 2021 and 2022 for the
chrysanthemum cut flowers trade in Serbia. The average import of chrysanthemum cut
flowers was 474.6 metric tons with average value of 0.65M (USD). During the pandemic
years, the amount of imported chrysanthemums did not change significantly, average amount
was 478.2 metric tons, but value of imports was considerably higher, reaching average value
of 1.67M (USD). The export of chrysanthemum cut flowers decreased over years, and values
of export became insignificant during the pandemic years. Taking into account the rising
prices of chrysanthemum cut flowers, and that Serbia has favourable conditions for
chrysanthemum production, we can conclude that it is important to increase chrysanthemum
cut flowers production in Serbia
Genofond retkih i ugroženih vrsta drveća Specijalnog rezervata prirode „Goč – Gvozdac”
No full textУредбом о проглашењу Специјалног ре-
зервата природе „Гоч-Гвоздац“ („Службе-
ни гласник РС“, број 99/14. од 11.09.2014.
године) ово подручје је стављено под
заштиту: ради очувања значајних мешо-
витих шумских екосистема буково-јело-
вих шума (Abieto-Fagetum serbicum), шума
црног бора (Potentilo-Pinetum gočensis),
субалпијских букових шума (Fagetum
subalpinum) и шума планинског јавора са
буквом (Acereto Heldreichii-Fagetum); да би
се очувале јединствене биолошке, гео-
лошке, геоморфолошке и хидрогеолош-
ке појаве и феномени; да би се очувао
велики диверзитет флоре – 715 биљних
врста међу којима су од највећег зна-
чаја варијетет црног бора (Pinus nigra var.
gočensis) и ендемит Балканског полуострва
планински јавор (Acer heldreichii) и бројне
ендемичне, ретке и угрожене, међуна-
родно значајне биљне врсте, као и фауна
коју чини 317 врста инсеката, 129 врста
птица, 20 врста водоземаца и гмизаваца
и 27 врста сисара међу којима су видра,
хермелин, велики пух и ласица. Такође,
овај резерват природе има значајну уло-
гу као огледно добро за потребе наставе
и науке различитих образовних профила
(слика 1.1., 1.2). Управљање резерватом
поверено је Универзитету у Београду –
Шумарском факултету
Envisioning the future-Creating sustainable, healthy and resilient BioCities
No full textNumerous challenges - from population increase to climate change - threaten the sustainable development of cities and call for a fundamental change of urban development and green-blue resource management. Urban forests are vital in this transition, as they provide various ecosystem services and allow to re-shape and re-think cities. Based on a Europe-wide community effort with diverse experts centered around urban forests and urban greening, we propose five key research fields to generate the knowledge required to unlock fundamental changes in urban development and green-blue resource management: circular bioeconomy, climate resilience, gover-nance, social and human environment, and biodiversity. To support the design of greener, cooler, more inclusive and resilient cities, all these research fields require inter-and transdisciplinary collaboration, engaging stake-holders in transforming urban engagement and functioning. We summarise main inter-, trans-und multi-disciplinary research paths for each field and the cross-cutting knowledge areas that can help to address the challenges many cities face (e.g., modelling and assessment of the urban microclimate). For transforming cities further knowledge is needed on e.g., urban innovation, transition, participation, and more. Finally, we address how the identified research gaps can be implemented (e.g., international coordinated research effort, interdis-ciplinary networks)
The affine ensemble: determinantal point processes associated with the ax plus b group
No full textWe introduce the affine ensemble, a class of determinantal point processes (DPP) in the half-plane C+ associated with the ax + b (affine) group, depending on an admissible Hardy function 0. We obtain the asymptotic behavior of the variance, the exact value of the asymptotic constant, and non-asymptotic upper and lower bounds for the variance on a compact set it C C. As a special case one recovers the DPP related to the weighted Bergman kernel. When iota l iota is chosen within a finite family whose Fourier transform are Laguerre functions, we obtain the DPP associated to hyperbolic Landau levels, the eigenspaces of the finite spectrum of the Maass Laplacian with a magnetic field