The aim of this study was to investigate the floristic composition and diversity of seven urban habitat types in 24 Serbian cities with different climatic affiliation. In each of the 24 cities, we selected 1 ha plots representing a habitat from one of the following groups: square, boulevard, residential area with compact and with open building pattern, city park, and sites with early and mid-succession vegetation stages. All vascular plant species that occur spontaneously in these plots were observed. Data on the main climatic characteristics were collected for each plot, and data on the life forms were obtained for each species recorded. Diagnostic species were identified for each habitat type analyzed, and alpha, beta and gamma diversity were calculated. A total of 674 taxa were recorded in the studied area. Significant differences were observed in habitats by diagnostic species and by life form representation. The lowest alpha and gamma diversity and the dominance of therophytes were observed in habitat types with intensive anthropogenic impact, whereas the highest number was recorded in mid-successional sites and residential areas with a compact building pattern. The analysis showed that habitat type influences species composition much more than climate.

This paper emphasizes the advantage of using carbon polymers while producing and strengthening glulam beams. Due to advanced research carried out in this field, the first application of carbon polymers based products was implemented in Western countries. Structural elements containing carbon polymers, or being reinforced by them, show higher resistance and durability properties, as well as the ability to be produced in various shapes. These features can find best application in architecture so the architects? imagination in design could be realized. Many attractive buildings were constructed over the last decade, each of them showing exceptional safety, resistance to atmospheric influences, durability and cost-efficiency. Beside application of carbon polymers in the construction of new buildings, they are even more important in the field of historic heritage restoration. The original research carried out on ten samples in the laboratory is presented in the second part of the paper. Position of the reinforcement on the samples was chosen as it would be done in practical retrofit cases. Deformations of the samples exposed to pure bending were measured, so their behaviour in the elastic range could be analysed based on the results. Measured results were compared to those calculated by using FEM model, developed with software package AxisVM. Based on performed analysis, the conclusion was made that by strengthening timber glulam beams with FRP strips, the simple and efficient static load bearing capacity upgrade is gained.

In the last two decades, the number of research articles with a focus on urban ecosystems in Europe has increased significantly. However, explored cities are very unevenly distributed, and most of the studies are focused on Central Europe. The aim of this analysis was to provide a realistic insight into the results of previous research on urban flora and vegetation in Southeast Europe. The analysis covers a total of 149 articles, which are classified according to the topic and concept of research. The rates of exploration of urban flora and vegetation vary considerably across the countries of Southeast Europe. The floristic approach was the most common in most of the countries. Although some countries of Southeast Europe have a significant number of floristic studies (e.g. Serbia and Croatia with more than 20 of each country), their urban flora is still insufficiently explored compared to other European regions. Also, the use of different methodologies makes it impossible to compare results in an adequate way and draw relevant conclusions. Unlike the studies in most of Europe, with a broader spatial framework and uniform methodology, in Southeast Europe they usually referred to individual cities, specific habitats or certain parts of the cities. Hence, including Southeast Europe in large-scale studies would be beneficial.

This study represents the first data gathering and analysis of the floristic composition of ruderal vegetation in Serbia, published over the last 70 years. The dataset included 748 relev?s of ruderal communities and a total of 716 plant species and subspecies. The study showed that the most abundant were widespread taxa, especially taxa of the Eurasian area type, while alien species accounted for a relatively small proportion of the ruderal flora (about 10%). Therophytes and hemicryptophytes were most abundant in the life form spectra. Five vegetation groups were identified, corresponding to the following vegetation classes: Bidentetea, Sisymbrietea, Digitario sanguinalis-Eragrostietea minoris, Artemisietea vulgaris and Polygono-Poetea annuae. The analysis of similarity showed that there are small floristic differences between particular vegetation groups. The determined diagnostic species for the vegetation groups were compared with those of the corresponding anthropogenic vegetation classes, and a high degree of similarity was found for all but one group. The most frequent taxa in all five groups were Polygonum aviculare, Convolvulus arvensis, Plantago major subsp. major and Chenopodium album.

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Recycling has an important role in modern production and in environment preservation. Introduction of recycled PET ((Poly) Ethylene-terephthalate) as straps for reinforcement bars in concrete construction elements can help these important issues. By using an experimental method it is shown that PET straps made with minimal investment, on site and with manual production can replace "annealed" wire as element for connection of reinforcement bars. An overview of some regulation and procedures is presented and used for eligibility assessment of the proposed straps made of recycled material. Also an overview of commonly used connections is given so it can be compared with the proposed ones.