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.

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.

Long-term courses of water protection and management are based on the fact that Serbia belongs to the region of UNECE countries (UN Economic Commission for Europe) while most of its territory belongs to the Danube River Basin where countries have established multilateral coordination and cooperation in water management. Since the Republic of Serbia is currently in the process of joining the EU, it is obliged to gradually align its strategic decisions in the field of water to the documents that apply to EU member states. The degree of the state's readiness to join the EU will be assessed based on the adequate introduction of internationally accepted principles of water management into the strategic documents and their establishment and implementation at the state level and within international cooperation in this area. Serbia will not be granted EU membership unless it invests significant funds in wastewater and polluted water treatment, as this is one of the priorities in meeting the criteria to open Chapter 27. The introduction of biological systems into the standard water treatment infrastructure provides higher levels of environmental protection and contributes to the integration of environmental requirements, opinions and principles into the plans and programs that encourage and promote sustainable development. The paper will present the current level of alignment between EU and Serbian water-related legislation and propose specific guidelines for the introduction of biological systems for the treatment of polluted water in strategic documents in Serbia.

In urban areas treelined paths are the most vulnerable element. According expected functions treelined paths in certain street are unsatisfactory with their appearance and general condition. These are primarily biological, ecological, sociological and aesthetic functions. Because of negative anthropogenic influences trees are with low level condition, very low functionality and the unsatisfactory state of health. Most of the trees exist in very difficult circumstances of streets, there are crowded in the underground and in the aboveground part. In such circumstances, just as individual specimens of trees grow into individuals who manifest themselves in terms of morphology characteristics which are representative of its species. In this paper is presented the state of the avenue of horse chestnut (Aesculus hippocastanum L.) in two central streets of the old part of Obrenovca. The data were analyzed on the basis of the reviewed every tree and with the particular assessing the state of the crown and the state of the trunk. Based on the analysis of the results measures are proposed for the rehabilitation of individual trees as well as measures for the reconstruction of the entire tree line.