Application of multispectral sensors and unmanned aerial system in Stara Planina region

In the area of Stara Planina mountain, a multispectral survey of forest vegetation was performed. Data acquisition was done with unmanned aerial system DJI Phantom 4 Pro, equipped with integrated RGB 20Mpix sensor, and MicaSense RedEdge M, 5-channel narrowband multispectral sensor. Data was collected in the form of images, and 4 composite orthomosaics were produced-broadband visible RGB, narrowband visible RGB, and with vegetation indices applied NDVI and NDRE. RGB orthomosaic showed no significant changes in canopies apart from the variability of levels of green. Orthomosaics with vegetation indices applied showed changes in the level of physiological activities of leaves. NDVI map showed the negative changes of the top of the canopies, while NDRE map showed more dramatic changes within the canopy as well. Besides the map, 5 polygons with different NDRE values were selected and their respective spectral signature graphs were produced. The areas with the lowest NDRE values had the highest reflectance values in all wavelengths, while the absorption of light is much higher in physiologically active vegetation. Values of NDRE lower than 0.479 were inspected from the ground. This kind of ground-truth provided evidence that the areas coded in red were with lower physiological activity due to the infestation by beech leaf-mining weevil Orchestes fagi L. Another interesting finding was that both NDVI and NDRE values were higher in the areas not directly exposed to the sunlight. The areas shaded by surrounding canopies received only diffuse light but it showed a more positive ratio between absorbed and reflected wavelength which could be characteristic of the Fagus Sylvatica species. The findings in this study showed a strong correlation between low values NDRE vegetation index and negative changes deep within the canopy of high vegetation, which can serve as an indicator of pest infestation in forestry.

Hunters in Europe: What does it mean "the hunters population" in Europe?

According to FACE (The European Federation of Associations for Hunting) approximately 7 million hunters are registered in Europe. Throughout the year they work in nature, in the hunting ground, or organize work of supporting teams and individuals on development of habitats with different kinds of animals, of which only some are hunted or listed as game. By using methods of positive selection and care in order to increase quality and quantity of the habitat itself, is maintained and permanently increased biological diversity of plant populations and whole ecosystem same as animal populations, including game. Disappearance of certain animal species in certain parts of Europe surely is not caused by game management, but is a result of rapid urbanization and development of urban and rural areas with all the supporting infrastructure. Human overpopulation parallel brought to reduction of habitat areas for numerous animal and game species. It's therefore required to establish balance between humans and other beings on a certain space, which therefore requires good management. The most competent members of human community which can manage wild animals and game in the most competent way are certainly hunters. In every community mutual understanding and cooperation of all other stakeholders and ecosystem beneficiaries is key. We should not forget that a human is part of natural ecosystem and a hunter is the most competent person who understands habits and life of game animals and therefore can manage it in the best way. Due to this reason game, hunter and hunters population take care of the game animals survival, their overall food chain their development and relative relationship in order to avoid deterioration and favoring of certain species over the other, increasing biological diversity of game animals and habitat which they inhabit; of overall and particular individual health state, of active and passive protection defining and implementing regulations important for behavior and management, on the basis of good management and good will in this way actively and significantly contributing to development of environmental protection.

The most important mycoses of Austrian pine (Pinus nigra Arnold.) in the Avala area

Austrian pine is one of the species most often used for afforestation in our conditions. In the area of Avala, afforestation with Austrian and Scots pine began in 1899. The stands of Austrian pine located on the northern and northwestern foothills of the Avala Landscape of Outstanding Features are 115 years old, while the stands on the southern and southeastern side are about 65 years old. Two-year research in the area of Avala recorded the presence of 18 species of fungi on Austrian pine. Out of that number, 6 fungi were found on needles, 5 on needles and seeds, 2 on roots and stem bases, 1 on cones, 3 on trunks and branches and 1 species in vascular bundles. Of all the species, the greatest damage is caused by Sphaeropsis sapinea and species of the Armillaria genus.

Corylus L.: Its diversity, geographical distribution and morpho-anatomical characteristics with special reference to the systematic classification and phylogenics of Turkish hazel (Corylus colurna L.)

Botanists have not yet reached an agreement regarding the number of species and lower taxa within the Corylus L. genus (hazel). According to different literature sources worldwide, 14, 16,18, or 20 species have been described within the genus. There are many synonyms in the scientific literature for the same species, which creates additional confusion in determining the total number of species within the genus. According to the WCSP (World Checklist of Selected Plant Families), (http://apps.kew.org/wcsp/synonomy.do?name_id=47827), 16 species have been recognized worldwide. According to this valid classification based on morpho-anatomical characteristics, all hazels are divided into two sections, and each section into two subsections. The paper presents the main differences between these groups and subgroups, as well as their distribution in the world. Special attention is given to the range of distribution, morpho-anatomical characteristics, systematic classification, and relatedness of Corylus colurna L. to other species.

Guidelines for the introduction of biological systems for revitalization of polluted water and wastewater treatment in strategic documents in Serbia

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.

The health condition of tree and shrub species of Topčider Park

The research deals with the health condition of tree and shrub species of the natural resource known as Topčider Park assessed on the basis of the conducted visual assessment and determination of the degree of defoliation and discolouration. During the growing season 2018-2019, the health condition of plant species belonging to 50 different genera was determined. The following species were found to be healthy, without any visible damage: Cedrus atlantica, Corylus avelana, C. colurna, Juglans nigra, Maclura aurantiaca, Mahonia aquifolium, Prunus cerasifera, P. spinosa, Quercus rubra and Sambucus nigra. Trees with visible injuries included: Acer negundo, A. pseudoplatanus, Aesculus hippocastanum, Cryptomeria japonica, Fagus moesiaca, Gleditsia triacanthos, Morus alba, Platanus acerifolia, Populus alba. P. nigra, and P. tremula. Dying trees and dead trees were not recorded in Topčider Park. The plant species most threatened by the attack of pathogenic fungi and fungus-like organisms were the species of maple, horse chestnut, lime, poplar, and plane. The species of insects and mites here present did not significantly affect the health status of the investigated plant species.

Phytosociological characteristics of sessile oak and hornbeam forests (Querco petraeae-CarpiInetum betuli Rudski 1949. s.l.) in the area of Kosmaj

The paper presents phytosociological characteristics of the sessile oak and hornbeam community (Querco petraeae-Carpinetum betuli Rudski 1949. s.l.) in the area of Kosmaj. Phytosociological relevés of the investigated association were taken at altitudes ranging from 339 to 410 m, with Eastern to northeastern aspects, and the slope of 15-23°. The community occurs on deeply ilimerized soils - luvisols over flysch. The floristic composition of this phytosociological community is diverse, including plants from thermophilicmand mesothermal oak forests and some plants from beech forests. With regard to the spectrum of range types, the investigated community Querco petraeae-Carpinetum betuli Rudski 1949. s.l. has a Central European range of distribution. Regarding the bioloigical spectrum of life forms, most species are considered phanerophytes and hemicryptophytes, with an increased share of geophytes.

Forest ecosystems vitality monitoring (ICP forests, Level I) with special emphasis to the affected part of the sample trees in the Republic of Serbia

Trees condition on the sample plots of the ICP forests, Level I, is especially considered and monitored by the typically damaged and affected part of the tree on which it occurs. Due to the need to enter unique data for the measured parameters (visible damages), their codes are assigned for each damage. These are the results from Sample plots, Level I, based on the ICP methodology. The results are entered into a single database for all participating countries. Infested assimilation organs - leaves or needles are direct indicators of the condition of the trees. The most common damage to leaves is caused by miners, gnats, beetles, and insects that totally bite the leaves so parts of the leaves are completely missing (Lymantria dispar L.). The leaves are mined by Stigmellidae, Gracillariidae, Cynipidae forming galls; there are also damages from the early oak defoliators Geometridae and Tortricidae. Apart from defoliators, the most common are xylophagous insects (for example, bark beetles) as well as root pests. The fungi that most commonly occur on the leaves are oak powdery mildew (Erysiphe alphitoides) and Rhytisma acerinum (which attacks species of the genus Acer). Other damages that occur are verticillium wilt (diseases of the conducting vessels), beech bark disease, then rot of the appendix, trunk, and branches. The paper presents the observed damage and diseases on the experimental plots of the ICP forests, Level I, in Serbia, according to the parts of the tree where they were discovered.

Variability of morphometric characteristics of Hungarian oak (Quercus frainetto Ten.) acorn

The results of morphometric analysis of Hungarian oak seeds originating from Lipovica Forest Management Unit are presented in this paper. The seeds have been collected from 50 trees evenly distributed on the forest management unit area. The length, width and mass of acorns are measured on the sample consisting of 50 acorns per tree. The volume and shape index of acorns are calculated based on the measured values of their length and width. The mean values of morphometric characteristics obtained in research indicate there is a high variability among the studied genotypes. The latter has also been confirmed by means of an analysis of variance which determined statistically significant differences between the sampled mother trees for all the observed morphometric characteristics. The results obtained represent a good starting point for future research on breeding of the species and can be utilised for improvement of the mass production of high quality Hungarian oak planting material in Serbia.

Potentials of the assessment of the wood quality in standing trees by applying acoustic methods

Based on literature sources, the stress wave and ultrasound methods and tools designed for the evaluation of the effects of decay on wood are discussed in this paper. To make a review of the results obtained in numerous studies, the analytic-synthetic method was used and the evaluation of data was conducted. The results revealed high correlations between the measured properties and the actual wood quality. A number of studies show that the acoustic wave velocities correlate well to wood density and other wood properties. Changes in the acoustic velocity and wood density variations caused by decay have also been detected successfully using the ultrasonic tools. This means that wood quality can be assessed in situ and that the methods and devices in question can help us make the right decisions. Still, it must be pointed out that all the methods and devices used are only measuring and quantifying tools, and practical human experience cannot be replaced by any measuring tools.