Maya Benkova (1)*, Lyuba Nenova (1), Tsetska Simeonova (1), Vera Petrova (2), Angelina Мikova (1), and Irena Atanassova (1)

1. Agricultural Academy, ‘N. Poushkarov’ Institute of Soil Science, Agrotechnology and Plant Protection, 7 Shosse Bankya Str., 1330 Sofia, Bulgaria. E-mails: majaben@abv.bg*, lyuba_dimova@abv.bg, cecka_simeonova@abv.bg, an15mi011@gmail.com, i.d.atanassova@abv.bg
2. University of Forestry, Faculty of Agronomy, 14 Anton Naidenov Str., Studentski grad, Building D, 1700 Sofia, Bulgaria. E-mail: vera_zamfirova@abv.bg

The aim of study was to investigate the effect of wood biochar in combination with nitrogen fertilizer on soil properties and maize biomass. The experiment was conducted at the Tsalapitsa field (Plovdiv, Bulgaria) on Fluvisol. A randomised block design was established – three rates (0, 5 and 10 t∙ha-1) of biochar and two rates (130 and 260 kg∙ha-1) of N fertiliser (ammonium nitrate). Each treatment was in four replications. Biochar was obtained by pyrolysis (400 ºC) of oak bark. The plant samples (leaves, stems, cobs) were taken in three phases of maize growth. The soil samples were taken during growing period and after maize harvesting. The results showed that treatments with biochar in the presence of N fertilizer significantly increased yields in maize growth (р ≤ 0.05) compared to the variants with fertilizer only. Greater positive effect of biochar application was observed in the combination of low-rate biochar (5 t∙ha-1) and low rate of fertilizer (130 kg∙ha-1) on crop biomass in different growing stages compared to controls and the variant with high N and low biochar rates (increases were +24 % and +44 %, respectively). Slight increases in pH, organic carbon and cation exchange capacity in the variants with both rates of biochar and low level of mineral fertilization were observed in the Fluvisol. When N fertilizer was applied at high rate, soil pH decreased (0.5–0.7 units) and exchangeable Al (1 cmol∙kg-1) appeared due to the fertilizer acidifying effect. The pH in these variants is not a limiting factor for maize production.

Anzhela Dzyba

Department of Landscape Architecture and Phytodesign, Education and Research Institute of Forestry and Landscape-Park Management, National University of Life and Environmental Sciences of Ukraine, 19 General Rodimtsev Str., 03041 Kyiv, Ukraine. E-mail: orhideya_oncydium@ukr.net

In our work we determined the representation of trees that serve as hosts to common mistletoe (Viscum album L.) in protected areas of the Ukrainian Polissya. Our research goal was to conduct a quantitative and qualitative inventory of tree taxa damaged by the mistletoe. The study was conducted in 57 protected areas of the Ukrainian Polissya with a combined area of 715.22 ha. We identified 455 trees hosting 8586 mistletoe plants in 36.8 % of the entities covering 51.5 % of studied areas. The total number of host-tree taxa was 64, belonging to 9 families and 16 genera, with 45 tree species being on IUCN Red List. By bio-morphological characteristics, these 64 taxa were distributed among moesophanerophytes (44), megaphanerophytes (11) and microphanerophytes (9). By ecological characteristics, the dominant taxa were heliophytes (60.9 %), followed by moesotrophs (57.8 %) and mesophytes (46.9 %). Based on damage to host trees, 46.2 % taxa had low, 31.9 % - moderate, 10.5 % – high and 11.4 % – very high levels of mistletoe damage. The highest damage was observed on five species, including Tilia cordata Mill., Acer platanoides L., Populus simonii Carrière, Populus nigra L. and Juglans nigra L. By origin, 72.3 % of damaged host trees were introduced species, whereas by number of damaged trees, 51.4 % of trees were native. On study sites, in southern section of Volyn and Zhytomyr Polissya, the rate of mistletoe infestation per plant was high and constituted 43 and 41 bushes per host tree, respectively.

Nataliya O. Kin

Landscape Ecology Department, Steppe Institute, Ural Branch of the Russian Academy of Sciences, Orenburg, 460000, Russia. E-mail: kin_no@mail.ru

The forests, located in the conditions of steppe and forest-steppe zones, represent insular massifs with an extrazonal type of vegetation. Based on the unanimous opinion of scientists about the origin of insular pine forests and the assumption that pine forests in the past formed a single array with the zonal northern taiga, the concept of relict flora of insular pine forests arose. Scientists note that, despite the high degree of steppe species, the core of the flora is boreal in nature. The purpose of the study was to test the assumption of the relict nature of flora found in insular pine forests in the Russian Plain in contemporary conditions based on the analysis of the spectrum of latitudinal groups. We have studied the flora of the pine forests in the Russian plain: Usmansky and Khrenovskoy – located in the subzone of the typical forest-steppe of the Oka and Don Rivers lowland; Buzuluksky and Krasnosamasrky – occupying an area in the steppe zone of the Volga region. The flora of the forests in the steppe and forest-steppe zones fully reflects the natural and climatic features of these areas, which is clearly visible in the spectra of the latitudinal groups of the studied flora. One-third of the species in the floristic core are forest groups, which confirms the previously stated assumptions about the relict nature of insular pine forests. This was also confirmed by the analysis of the spectrum of latitudinal groups of rare species in the flora. In the floristic core, among the rare ones, there was a high percentage of forest species that determine its forest character. The data obtained also indicate that for many steppe and forest-steppe regions, forests may be the only habitats of forest species. For example, Drosera rotundifolia L., Calla palustris L., Lycopodium annotinum L., and Neottianthe cucullata (L.) Schlehter. 

Vasil Kolev* and Gradimir Gruychev

Department of Wildlife Management, University of Forestry, 10 St. Kl. Ohridski Blvd., 1797 Sofia, Bulgaria. E-mails: vassilie@abv.bg*; gradi.val@gmail.com

Fish diversity is an important indicator of a healthy river ecosystem. The article presents a study examining the current state of fish composition of the Ogosta River, western Bulgaria. Data was obtained by electrofishing along the river’s middle zone above the Ogosta Dam. The analysis recorded 12 fish species from 4 families. Most fishes are rheophilic. Four of it are specific for the North Bulgaria rivers and lower Danube basin. The fish fauna is strongly predominated by the Squalius cephalus.