Invasive species Symphyotrichum lanceolatum (Willd.) G. L. Nesom is spreading uncontrollably along wet habitats as well as in disturbed ecosystems. All those habitats function as corridors that facilitate seed dispersal. One way to prevent the spread of invasive species is to know their reproductive ecology. The present study evaluates the potential for generative reproduction of S. lanceolatum and determines how different temperatures, amounts of nutrients, and light regimes, affect seed germination. Seeds collected from 13 natural populations were germinated at four fluctuating temperature regimes (15/6, 20/10, 30/15, and 35/20 °C). To test the influence of nitrate on seed germination, two KNO₃ concentrations were used (5 mM and 50 mM solution). For each treatment, three replicates of 30 seeds were placed in complete darkness or a 14 h photoperiod. The results showed that the germination increased with increasing temperature. The optimal temperature regimes were 30/15 °C and 35/20 °C with approximately 88% germination. The overall effect of KNO₃ on germination was positive. The concentration of 50 mM KNO₃ had a less stimulating effect compared to 5 mM KNO₃. Seeds showed sensitivity to lack of light during germination but were able to germinate in a significant percentage in such conditions. Considering that S. lanceolatum often occurs in disturbed sites, these results suggest that seed reaction to alternating temperature, nutrients concentration, and light can be determining factors that affect seed germination of this species and, thus, its spread.

Water regulation, integral water management and water conservation are one of the main tasks, set by an ecologically conscious society. A series of complex treatments are set in order to achieve the main goal in wastewater treatment, i.e. eliminating or reducing pollutants to a level that will not cause adverse effects to humans and the environment. The paper presents the construction of an efficient, environmentally friendly and economically justified biological system for the treatment of polluted urban waters. Research has shown that the proposed system with floating islands and algae was effective in removing various categories of pollutants from polluted river (organic and inorganic matter, heavy metals and pathogenic microorganisms), which indicated that the selected type of construction was appropriate. It was concluded that minor modifications in terms of cell coverage by floating islands could provide even greater removal of certain pollutants such as nitrogen, phosphorus and heavy metals.

Spatial and urban plans have recently given an increased focus to the sensitive issue of planning the urban resilience of existing and establishing new urban forests. Urban forests are recognised as an extremely important factor of environmental quality, while scientific studies indicate that the health condition of urban forests is threatened by present-day climate change. There have been relatively few systematic assessments of the causes of tree die-back in urban areas in Serbia. Research, forest establishment planning and tree monitoring to estimate possible consequences to existing trees will enable city authorities and managing bodies to raise the issue of urban forest resilience to climate change to a higher level and incorporate it into urban planning. Future scenarios in which urban forests are resistant to potential adverse climate change will depend on the scope of activities of adaptive planning of urban forest establishment and adaptive management of existing ones. Therefore, it is necessary to conduct long-term studies of monitoring the condition of urban forests in the large cities of Serbia (Belgrade, Novi Sad, Niš, Subotica, etc.) in the coming period in order to identify specific problems and remediate the consequences such as deteriorated tree health condition and die-back.

Organic matter is considered one of the main sources of water pollution caused by the discharge of wastewater of different categories directly into rivers. The increased content of organic matter serves as a source of food for water microorganisms and significantly lowers dissolved oxygen of the recipient. Floating treatment wetlands (FTW) are an innovative green technology that removes excess organic matter from water. This paper shows the effectiveness of floating treatment wetlands in removing organic matter from the water of a polluted urban river. Cells with floating islands had BOD reduced by 84-91%, COD in the range of 57-65% and TOC by 16-20%. The highest efficiency in COD and TOC reduction was achieved in Cell I where P. australis was planted, and BOD in Cell II where C. indica was planted. The results of these studies showed that after 6 days of treatment of polluted water, a high reduction of BOD and COD was achieved, as well as a satisfactory reduction of TOC concentration.

The paper presents the results of the analysis dealing with the impact of plant fertilisation in the first year after planting on the leaf morphological characteristics. The analysis was conducted within the research into the potential introduction and adaptation of paulownia to different sites in Serbia. The results related to the effects of fertilisation on the quality of plant leaves are useful for the cultivation of certain types of soil where the morphometric analysis of leaves reveals structure-function relationships, i.e., more detailed indicators of the species' adaptability. The research was conducted in two localities. Sample plots with Paulownia elongata S. Y. Hu. and Paulownia fortunei Seem. Hemsl. were established in Obrenovac and Pambukovica, where leaf material was collected for laboratory analysis. The following morphometric leaf characteristics were measured: leaf area, leaf perimeter, leaf lamina length, central nerve length, maximum leaf width, leaf width at 1 cm from the base of the leaf, petiole length, distance between the 3rd and 4th nerve, the number of nerves to the left side of the midrib, and the number of veins to the right side of the midrib. The obtained results of leaf morphometric measurements were statistically processed in the Statgraphics software. Based on the results of measuring the leaf morphometric characteristics, fertilisation has a positive effect on the size of the leaves of the studied paulownia species.

Protected areas are essential for biodiversity conservation, ecosystem services, and protecting different cultural heritage. They are legally designated and managed to safeguard habitats, species, and ecological processes. The EU aims to protect 30% of its land by 2030, while in Serbia 9.74% of land is under protection. One of the important categories of protected areas represents national parks, which cover 17.3% of all protected areas in Serbia. In order to understand the mechanisms of financing national parks in Serbia, the period from 2008 to 2022 was analyzed. The 15-year period was selected due to the availability of data and the necessity for long-term analysis. All revenues are divided in four groups: business, fee, grant and other business revenues. The results of regression analysis show that the growth rate of business revenue is the most significant contributor among the revenue sources, with a very strong positive impact on the growth rate of total revenue in all four national parks. The growth rate of grant revenue also contributes positively to the growth rate of total revenue. However, its impact is much smaller than the growth rate of business revenue and fee revenue but still highly significant. A strong negative correlation (−0.82) is present between the growth rate of business and fee revenue in National Park Kopaonik. This suggests that with an increase in fee revenues, business revenues decrease. The results of this research show that business revenues are the most important, followed by fee and grant revenue.