Nataša Nikolić

Urban trees are exposed to multiple co-occurring stressors, including heat, drought, and pollution driven by intensified urbanization and climate change. These environmental pressures can compromise tree vitality by disrupting photosynthetic performance and oxidative balance. In this study, we assessed the structural, physiological, and biochemical responses of three common urban tree species (Tilia platyphyllos, Celtis occidentalis, and Platanus × hispanica) growing under urban environmental conditions in Novi Sad, Serbia. Leaf traits were measured during June and August to capture seasonal stress variation. Structural indicators (SPAD, leaf thickness, leaf temperature differential), chlorophyll fluorescence traits (Φ_II, Φ_NPQ, F_v′/F_m′), oxidative stress biomarkers (TBARS, proline, GSH), and antioxidant enzyme activities (APX, CAT) were quantified. The Tree Health Risk Index (THRI) was calculated to integrate multilevel responses. Results revealed species-specific differences, with Tilia exhibiting the highest sensitivity, characterized by notable photochemical declines and oxidative stress under urban conditions. Celtis showed moderate resilience, while Platanus demonstrated the most robust performance and emerged as a promising candidate for climate-resilient urban sites. Heatmap clustering and trait contribution analyses confirm oxidative stress biomarkers and chlorophyll fluorescence traits as key indicators of urban stress. This study emphasizes the importance of integrating functional trait-based approaches for assessing tree health in urban greening.

Accurate assessment of macrophyte diversity is essential for effective river ecosystem management. Discrepancies in sampling protocols can lead to variations in observed biodiversity, which may influence ecological monitoring and management strategies. This study evaluates and compares three sampling methods—the comprehensive “all” survey, Joint Danube Survey (JDS), and National Monitoring Program (NMP)—for assessing macrophyte diversity along the Serbian Danube. We applied Hill numbers and Chao estimators to evaluate sample completeness and diversity for species richness (q = 0), Shannon (q = 1), and Simpson (q = 2) diversity. Asymptotic diversity was estimated using rarefaction and extrapolation methods, and statistical analyses (ANOVA, permutation tests) assessed differences in diversity estimates across sampling methods. The “all” sampling method provided the highest sample completeness and reliable asymptotic diversity estimates, capturing 100% completeness for q = 1 and q = 2. The JDS and NMP datasets showed incomplete sampling for species richness (q = 0), with undetected species richness in both. However, both datasets captured all abundant species for higher diversity orders. Significant differences in diversity estimates between methods were found in some waterbodies, especially for species richness and Shannon diversity. The “all” sampling method most accurately captures true species richness and diversity. While JDS and NMP methods are valuable for assessing higher-order diversity, the two methods may underestimate species richness, particularly in heterogeneous river sections.

Shrubs are a significant component of urban vegetation found in parks, but they experience various influences from biotic and abiotic agents, among which aphids play an important role. In this work, the effects of aphid colonisation on three shrub species in urban environments were examined. Fourteen parameters were analysed, describing the photosynthetic pigment content and gas exchange to carbon, nitrogen, and hydrogen partitions. While no significant effect of colonisation was found on photosynthetic pigment parameters, the effect was significant on gas exchange parameters. The strongest effect of aphid colonisation achieved was on nitrogen partition and the C/N ratio, parameters that could be suggested for further similar studies. All parameters were classified into two groups according to their principal component analysis, suggesting a correlation between nitrogen and carbon content, the C/N ratio, measured gas exchange parameters, and chlorophyll a content. The ratio between net photosynthesis and dark respiration (A/K) was classified in the second group, suggesting that this parameter provides additional information on the effect of aphid colonisation and deserves special attention in further studies. There were differences in the effect of aphid colonisation on the physiology of the examined shrub species, especially in cases where a decrease in the C/N ratio was achieved in Spirea trilobata and Cydonia japonica, while an increase in the same parameter was recorded in Hybiscus syriacus.

Shrubs are a significant component of urban vegetation residing in parks, but they experience various influences of biotic and abiotic agents, among which aphids play an important role. In this work, the effect of aphid colonization on three shrub species in urban environment was examined. Fourteen parameters have been analyzed, describing photosynthetic pigment content and gas exchange to carbon, nitrogen, and hydrogen partition. While no significant effect of colonization was found on photosynthetic pigment parameters, the effect was significant on gas exchange parameters. The strongest effect aphid colonization achieved on nitrogen partition and C/N ratio, parameters that could be suggested in further similar studies. All parameters were classified in two groups according to principal component analysis, suggesting correlation between nitrogen and carbon content, C/N ratio, measured gas exchange parameters and chlorophyll a content. The ratio between net photosynthesis and dark respiration (A/K) was in the second group, suggesting that this parameter provide additional information on the effect of aphid colonization, and deserve special attention in further studies. There were differences in reaction of examined shrub species, where the strongest reaction by gross primary productivity (GPP) achieved Hybiscus syriacus, and by nitrogen partition and C/N ratio Spirea trilobata and Cydonia japonica.

The aim of the present study was to analyze the chemical composition of parsley, parsnip, carrot, and celeriac cultivated at different localities (urban, or suburban/village). The concentrations of heavy metals (cadmium, nickel, chromium) and essential elements (potassium, sodium, calcium, phosphorus) in edible plant parts were determined. Human health risks associated with chronic consumption of potentially contaminated vegetables were assessed through the use of hazard quotients. The concentrations of heavy metals and essential elements in the edible parts of the tested plants varied among plant species, cultivation locality and plant organ (leaf/root). Carrots showed the lowest levels of cadmium, nickel, and chromium accumulation, while the highest concentrations were measured for parsley leaves, with respect to average values. Metal pollution index values obtained for cities were lower than those obtained for some villages and a suburban settlement. The hazard quotient revealed the highest values for cadmium. Positive Pearson’s correlation between chromium and nickel was found in many cases. Principal component analysis indicated differences in plants ability to accumulate certain nutrients and pollutants, while sample diversification was closely related to growth site properties. We sincerely hope that the present study will inspire similar investigations in other developing countries, as well as in the Western Balkans region, to obtain broader insight into vegetable food safety and local human health risk. Considering that food quality and safety are major concerns, our results should inform the relevant government authorities and provide a foundation for implementation of a system of controls over cultivation processes and vegetable quality in Serbia.

Celery and parsley are recognized as medicinal herbs and nutraceutical vegetables due to their valuable pharmacological properties and numerous health benefits. However, in recent years, soil loadings with various PTEs have become a serious concern across the world, leading to plants pollution, which can consequently diminish their quality and safety for human consumption. Therefore, we attempted to quantify quality and safety of celery and parsley grown in Cd polluted soil. We examined the presence of PTEs: As, Cu, Fe, Mn, Ni, Cu and Cd in soil and selected herbs, as well as their physiological responses to different Cd exposures (control–without Cd addition, 3 and 6 µg/g Cd of dry soil). Following elevation of Cd in plants, both species showed increasing trend of As, Pb and Cu in plants, which overcome safe limits, with exception for Cu. Further, celery showed strong phytoextraction ability (99.9 µg/g Cd of dry weight) with high potential to tolerate Cd due to the efficient antioxidative machinery. Besides that herbs pollution was evident on the basis of target hazard quotients (HQ), hazard index (HI) and cancerogenic risk (CR), revealing that chronic consumption of contaminated herbs can consequently endanger human health. HI was greater than 1, while CR exceeded safe limits in treated plants, with exception for As. In the point of view of toxicology and food safety, growing of medicinal plants should be strictly regulated and distinguished based on the purpose of growing, and further herbs usage.

During the past decade, the target in cleaning polluted sites is an application of chelating agents, such as citric acid (CA), which is proposed as a good candidate in the promotion of phytoremediation. Among heavy metals, cadmium (Cd) is one of the most common and dangerous elements, which strongly disturbs morphophysiological properties in plants. A pot experiment was assessed to evaluate the influence of CA in Cd phytoremediation in alkaline soil by Salix viminalis (clone SV068). The effects of CA on Cd bioavailability, mobility, and distribution in plants, various morphometric measurements, and physiological performances as photosynthesis, transpiration, water use efficiency, and pigment content were tested. The highest Cd accumulation was evident after 60 days of growing, in plants subjected to combined treatment of CA with a higher dose of Cd. Application of CA showed a beneficial effect in maintaining the photosynthetic rate as well as gas exchange capacity in willows grown in Cd-contaminated soil. Furthermore, CA slightly increased plant growth and biomass production, depending on applied Cd dose and harvest period. A chelating agent like CA showed strong influence in plant response to combat Cd toxicity.