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In this work we analyse yearly standardized precipitation evapotranspiration index for accumulation timescale of 6 months (SPEI‐6) for August which has been identified as a strong proxy for corn production in Serbia. By applying recently proposed method generalized weighted permutation entropy (GWPE), which provides the information about predictability of large/small fluctuations in nonstationary time series, on SPEI index calculated from high‐resolution gridded dataset for the period 1951–2022, we found that the small fluctuation sequences of consecutive 4‐year SPEI values are the most predictable (indicated by lowest entropy values). The order of large fluctuation sequences is less predictable, while the order of sequences considering all magnitudes of fluctuations are the least predictable (indicated by highest entropy values). We also analysed 4‐month SPEI‐6 sequences for May, June, July and August (during the growing season of corn) along the years under study and found that they display lower GWPE values and thus are more predictable than yearly SPEI‐6 August sequences (small fluctuations displaying lower entropy values than large fluctuations). Regarding spatial distributions, in both cases SPEI‐6 sequences show similar pattern for large fluctuations: higher predictability (lower entropy values) in northern and eastern part of Serbia and lower predictability (higher entropy values) in southern and western part. For small fluctuations spatial distribution of GWPE values indicates that yearly SPEI‐6 August series are more predictable in the western part of the country while May to August monthly SPEI‐6 sequences are more predictable in the eastern part. [ABSTRACT FROM AUTHOR]

This paper focuses on the possible impact of the thermal soil regime on the occurrence of forest fires in the Zaječar administrative district in Eastern Serbia. The study uses data on soil temperature from the Republic Hydrometeorological Service of the Republic of Serbia and the ERA5-Land gridded reanalysis dataset for monthly temperature and volumetric soil water of the soil level 1 (0-7 cm), and soil level 2 (7-28 cm) with horizontal resolution of 0.1°C (approximately 12 km × 12 km) during the period of 2009-2021. Differences in soil temperature at depths of 2 cm, 5 cm, 10 cm, and 20 cm at the meteorological station in Zaječar for the periods 1961-1990 and 2009-2021 are observed. By analyzing the data on the registered number of forest fires for the period 2009-2021, pronounced oscillations in the dynamics of forest fires can be observed. The minimum number of forest fires (0) is registered in 2014, when the maximum of soil moisture in the soil levels 1 and 2 is observed. A high number of forest fires corresponds to high soil temperatures in 2012 and 2017. Soils drier and hotter than the average are registered in 47.0% of all months with the fire occurrences. About 50% of fires occurred in dry and hot soils during 2012 and 2017. This percentage was zero in 2014, when there were no fires. [ABSTRACT FROM AUTHOR]

Humans and many animals have forward-facing eyes providing different views of the environment. Precise depth estimates can be derived from the resulting binocular disparities, but determining which parts of the two retinal images correspond to one another is computationally challenging. To aid the computation, the visual system focuses the search on a small range of disparities. We asked whether the disparities encountered in the natural environment match that range. We did this by simultaneously measuring binocular eye position and three-dimensional scene geometry during natural tasks. The natural distribution of disparities is indeed matched to the smaller range of correspondence search. Furthermore, the distribution explains the perception of some ambiguous stereograms. Finally, disparity preferences of macaque cortical neurons are consistent with the natural distribution.

We investigate multifractal properties of daily means of air temperature over the territory of Serbia, by using Multifractal detrended fluctuation analysis. Temperature anomalies in two periods 1961–1990 and 1991–2020 are calculated from the E-OBSv26.0e gridded dataset with 0.10° (~12 km) resolution, totaling 1278 daily temperature series for each period. The MFDFA parameters: position of the maximum of the spectrum α0, width of the spectrum W and asymmetry r, obtained from the total of 2556 MFDFA runs are interpolated to yield their spatial distribution across Serbia in the two periods. We found several patterns in both the spatial distribution, and changes from first to second period. All series showed multifractal properties with overall persistent long-term correlations (α0 > 0.5) and the dominance of small fluctuations (r > 0). The persistence is weaker (smaller α0 values) and multifractality is stronger (larger width W) in southern mountainous regions. In the second period the values of α0 increased indicating stronger persistence of temperature dynamics, while multifractality became stronger (larger W) in northern region and weaker (smaller W) in southern region. In both periods the contribution to multifractality was dominated by small fluctuations (r > 0) that become stronger in the second period, indicated by the increase of the values of r over most of the country's area. These changes in the values of multifractal parameters indicate the increase of complexity of temperature dynamics in the second 30 years period which could be related to climate change. [ABSTRACT FROM AUTHOR]

Recently, biofertilizers are recommended as an alternative or supplement for mineral nutritients. Active agents in biofertilizers are microorganisms that are involved with their activity in the preparation of herbal assimilative and other biotic substances for plant needs. In this study, the influence of Bioaktiv bioproduct on the lettuce yield and rhizosphere microflora of lettuce was tested. 'Bioaktiv' contains the active substance consisting of following microorganisms: Bacillus subtilis, Azobacter sp., Penicillium oxalicum and Fusarium sp. In the tested soil samples of lettuce rhizosphere, the total number of bacteria, Azotobacter sp., ammonifiers, oligonitrophyls, actinomycetes and fungi were determined. The total number of bacteria, Azotobacter sp., ammonifiers, oligonitrophyls, actinomycetes was increased while the number of fungi in the variant with biofertilizer was slightly lower than in the control variant. The application of this bioproduct affected on earlier formation of the lettuce head and overall higher yield.

The seasonal analysis of warm days in Belgrade and Niš is presented using climate indices Warm/Dry (WD) and Warm/Wet (WW) days, which are based on the daily mean temperatures and daily precipitation. Day is conceived as warm if the daily mean temperature is greater than the 75th percentile. Day is considered as dry (wet) if the daily precipitation are below the 25th percentile (higher than the 75th percentile). Analyses are made for the period 1950-2009 for Belgrade and Niš. It is obtained that the number of WD days, as well as WW days incresed in both cities, in Belgrade more than in Niš.

Knowledge of aridity is necessary to explain the characteristics of the geographical landscape. Increasing aridity due to global warming can be a real hazard, with the threat of desertification. The main aim of this paper is to introduce special software for aridity indices calculation (AICS), and on the basis of those data to peruse aridity as a natural hazard. These indices were calculated from data obtained from 10 meteorological stations in the Vojvodina region for the period from 1949 to 2006. In order to calculate the De Martonne aridity index, IDM, and the Pinna combinative index, IP, software was created using C# programming language. Not only that this software shows the values of indices, but also it shows to which class it belongs according to the De Martonne climate classification. Graphical presentation of both calculated indices is also enabled. Further development of AICS is planned. As additional software package here was used ArcMap 10.1 for the spatial representation and visualization of the aridity indices. [Projekat Ministarstva nauke Republike Srbije, br. 176020 i br. 176013]

The present work is an analysis of the daily minimum temperatures during the period 1949-2009 in Belgrade and Niš using the climate indice TN10p, i.e. a number of days per year with the minimum temperature less than the 10th percentile (cold nights). A positive trend of the absolute minimum temperatures is found in Belgrade and Niš. It is calculated that the TN10p, i.e. number of cold nights decreases. A greater decrease of number of cold nights is recorded in Belgrade than one in Niš. The greatest decrease is observed on the annual basis, while smaller decrease is observed in autumn.

An analysis of heat waves is done using the Heat Wave Duration Index (HWDI) for Belgrade and Niš. The length and severity of heat waves at two meteorological stations in Serbia were analyzed based on the daily maximum temperatures during the summer (June, July and August) and winter (December, January and February).

Climatic changes in the last two decades on global level are presenting the fact that the planet Earth is getting warmed up. Significant temperature increasing on global level has consequences in air temperature changing on even smaller proportion. The aim of this paper is to analyze trends in air temperature, as a very important meteorological element for successful grapevine growing. Trend analysis was done based on data collected throughout the Niš-South Morava region, which was by last viticulture regional division of Serbia in 1976, separated into six sub-regions. In each sub-region, data from no less than one meteorological station were analyzed. Zone, which was named "Niš-South Morava" by the authors, includes parts of south and south-east Serbia. According to the last viticulture regional division of Serbia, 50% of area in Serbia under vineyards are situated in this Niš-South Morava region. Trend of significance on 95% level of confidence, was obtained for mean annual air temperature in all six sub-regions. Trend of mean annual air temperature during the vegetation period is significant in five vinegrowing areas. Significant trends in the whole region are increasing, which was determined by linear regression equation. Obtained equations are used to create a new list of recommended grapevine cultivars in conditions of higher mean air temperature. .

Climatic changes on the global level have consequences in changes of meteorological and climatologic conditions in vinegrowing areas. The aim of this paper was to analyze trends of the meteorological elements and determine suitability of growing grapevine cultivar in a viticulture region. Trend analysis was done, based on the data for South-Banat sub-region, an important resource for the production of grapes and wines in Pannonia plain (Vršac: H=83m, φ=45 09 N, λ=21 19 E). Trend of significance for the 95% level of confidence for mean air temperature and sunshine duration was obtained for the May - June period. For those elements, trend was increasing as well as for the precipitation in September. Correction of cultivar list was recommended, considering the obtained trends of the meteorological elements. The grapevine cultivars that ripen earlier (table and wine cultivars) are recommended, as well as those created at the Faculty of Agriculture, Department for Viticulture. .