One of the problems that may arise when conducting long-term monitoring of bird populations in forest landscapes may be discrepancies between data obtained by different researchers. Using acoustic monitoring may solve this problem. To establish the suitability of the acoustic method for monitoring the state of forest ecosystems, studies were conducted in May and June 2018 on seven plots different from each other by stand age and species composition in a maple-linden-oak forest in northeastern Ukraine. The species composition of birds, the structure and composition of the stand and the values of six acoustic indices were calculated. Differences were found in all acoustic indices at different sites. The smallest values of the indices were noted in the overgrown clear-cut. Four acoustic indices in the May survey and five of the six in the June survey show significant correlations with the species richness of birds. All indices correlate with the values of several stand variables, which characterize the size and species composition of the stand, understorey and field vegetation, the closeness of various vegetation tiers, and with the distance to the edges and the nearest populated areas. The results suggest the possibility of using an acoustic approach to monitoring the bird population and the state of forest ecosystems.

This investigation was carried out in a forest on the southern borders of the Central-Russian Upland, on the Prioskolsky plateau, in the Srednedonskoy subprovince of the Pontic steppe province. The aim of this work is to identify the peculiarities of structure and ways of formation of the breeding population of ravine oak forests on the border of two geographic zones. The objectives of the work were to describe quantitative and qualitative characteristics of the population of the nesting birds of ravine oak forests, as well as provide an analysis of the faunogenesic structure of the nesting bird population. To obtain data on the species composition and density of nesting birds we used the line transect method by D. Hayne – Y. Ravkin. The surveys were carried out in 2011–2015 three times per season (April to June). The indicators of the breeding density of each bird species and the totals for each year were calculated. The Polydominant Simpson index was used to characterize species diversity. To evaluate the uniformity we used the calibrated version of G ‘Alatalo index F’. The calculations were performed using the program PAST. In total we observed 34 species of birds over the 5 years of research. The dynamics of the total density of breeding birds in the period researched (2011–2015) showed a maximum in 2013 (1,711 pairs/km2); the average index for the 5 years was 1,288 ± 133 pairs/km2, which is similar to the characteristics of the populations of birds forests of the steppe zone (Donetsk Ridge, Azov Upland). The dominant and subdominant species comprised 32.2–54.7% of the population, indicating a balanced community, in spite of the insular nature of the forest. The absolute dominant in all years was the Chaffinch (an average of 21.2% of the population); subdominant species were the Robin (11.2%), Great Tit (10.5%) and the Collared Flycatcher (10.3%). Over a third of the total number of birds are the hollow-nesting birds (37.1%); species nesting in the crown were 32.3% and ground-nesting species 25.3%. The geographical and genesis structure of the communities of nesting birds are characterized by predominance of species from Nemoral and Ancient-Nemoral faunal assemblage (in some years up to 90.9% of the population). The species from the forest-steppe faunistic complex of the European type of fauna account for 3.6% to 9.48% of the population of nesting birds, and most of these have the status of third-degree (rare species). The composition of the group of third-degree species is highly diverse: in addition to the elements of Nemoral, Ancient-Nemoral and forest-steppe complexes, it includes species from the tropical and boreal groups. Among third-degree species there is a tendency to decrease in some species from the Nemoral faunal complex with a simultaneous increase in the forest-steppe faunistic component and increase in the homogeneity of the geography-genesis structure as a whole. The significant share of the population from the Nemoral and Ancient-Nemoral species complex, which formed in deciduous forests, is evidence of the origin of the  researched ravine oak wood as a remnant of the once vast oak-forest areas.

Dry grassland ecosystems are highly fragmented in Ukraine and increasingly threatened from intensification of farming practices. Evaluation of the habitat conservation importance based on multitaxon studies allows for optimizing selection of priority sites. Botanical research of xerothermic habitats in the Kryvorizkyi Iron Ore Basin has been conducted since 2012, while spiders were investigated for the first time in 2017. In the four study sites, we recorded 265 vascular plant species (23 under protection) and 95 spider species (19 are rare). Both vegetation and spider communities of the site Zelena Gully are well preserved and rich in rare and threatened species (18 plant and 11 spider species), which confirms its value as a priority site of the Emerald Network. Chervona Gully and the Slate Rocks should be included in the network. Frequent fires and intensive grazing in Khrystoforova Gully affect the spider diversity, decreasing the number of specialist and rare species, while early flowering plants benefit from this disturbance. Nevertheless, its vegetation is poorer than in Zelena and Chervona gullies. Inclusion in the Emerald Network is critically important to the investigated sites, since expansion of mining activities is constantly threatening natural habitats in industrial regions.

We investigated the properties of the sounds recorded on the territory of the National Park “Homilshanski Lisy” (Kharkiv region, Ukraine). Recordings were made at five points (in mature, middle-aged, and young oak forests, overgrown clear-cut and aspen forests). Data collection was carried out using on-site positioning of AudioMoth autonomous recorders, located on trees at a height of 1.5 m. The recording was made from April 11 to July 10, 2020, for 3 h in the morning and evening with a 5-min duration followed by a 10-min pause (24 recordings per day). Six acoustic indices (AIs) were calculated: Acoustic complexity index (ACI), acoustic diversity index (ADI), acoustic evenness index (AEI), bioacoustic index (BI), normalized difference soundscape index (NDSI), and acoustic entropy index (H). For the analysis, we used the Friedman test as well as a nonparametric analysis of the variance of the distance matrix and Tukey’s test. The results of the analysis showed the statistical significance of the influence of forest type, date and time of recording, as well as the effect of their pairwise interactions on all six acoustic indices, both in the morning and evening. For three indices – ACI, BI, and NDSI – the highest average values were noted in a mature oak forest and the lowest was in overgrown clear-cuts. We performed a PCA to reduce the number of variables and obtain insight into the variable relevance. The cumulative percentage of variance, explained by the first three principal components, is 84.5%. The first principal component is associated with H, BI, AEI, and ADI. The second and third principal components are associated with NDSI and ACI. The obtained results correspond to the results of quantitative bird counts carried out earlier in this area.