Issues

The barn owl, Tyto alba (Scopoli, 1769), is an opportunistic nocturnal predator which diet tracks ecological changes in its habitat. To assess temporal dietary changes in a Saharan palm grove ecosystem, 402 pellets were collected between July 2022 and August 2023 in the Ranou palm grove (Touggourt, Southeastern Algeria) and compared with baseline data from 2009–2010 published by Hadjoudj et al. (2020). A total of 1353 prey items belonging to 29 species across four taxonomic classes were identified. Mammals dominated the diet in terms of relative abundance and estimated biomass. Commensal rodents increased markedly over the study period, particularly Mus musculus (Linnaeus, 1758) and Rattus rattus (Linnaeus, 1758), with the latter accounting for 47.7 % of the total biomass. Conversely, desert-adapted species of Gerbillus (Desmarest, 1804) declined significantly, while bird prey increased markedly, with Palaearctic migrants recorded for the first time. The reptilian component shifted from Lacertidae to Gekkonidae. Predation on the cricket Brachytrupes megacephalus (Lefebvre, 1827), a major agricultural pest in Saharan environments (Gryllidae), suggests a potential contribution of T. alba to regulating agricultural pest populations. These findings highlight the value of temporal dietary monitoring in assessing ecological changes and biodiversity dynamics in arid environments.

Received: 24 May 2026 / Accepted: 19 July 2026 / Available online: 06 August 2026

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Under global climate change, forest ecosystems play an increasingly important role as carbon sinks, while the carbon accumulation capacity of Scots pine stands is strongly influenced by stand age, forest site conditions, and ecological status. Regionally adapted phytomass models are therefore required to improve carbon-stock assessment, support reforestation planning, and estimate potential losses caused by forest degradation, fires, and logging. This study aimed to develop models of the above-ground phytomass of Scots pine stands in the Ukrainian Polissya and its north-western outskirts, taking into account stand age, bioproductivity, and forest site type to assess their carbon accumulation potential. The research was conducted in 2023–2024 within the Volyn, Rivne, and Zhytomyr regions. It covered 302 temporary sample plots established in natural Scots pine stands of varying ages (8–100 years) in accordance with the national standard. The results showed that the average density of above-ground phytomass ranged from 160–180 kg·m–2 in loamy sand infertile pine site types to 440–465 kg·m–2 in moist fairly infertile pine site types, where middle-aged and mature high-yielding stands with high density and well-developed crown mass predominate. In fresh fairly infertile pine site types, phytomass was 310–345 kg·m–2, while in dry fairly infertile pine site types, it was 190–230 kg·m–2. Mathematical modelling enabled the construction of logarithmic regression models describing the relationship between stand age and the specific phytomass conversion coefficients for wood, bark, and crown. It was established that conversion coefficients decrease with stand age, reflecting the regular reduction in the specific mass of individual fractions. The practical significance of these results lies in their application to spatial planning of reforestation, assessment of carbon potential, and the development of climate-oriented forest policy in conditions similar to those of the Ukrainian Polissya and its north-western outskirts.

Received: 10 April 2026 / Accepted: 21 July 2026 / Available online: 06 August 2026

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The aim of this study was to evaluate the seasonal microbiological and enzymatic responses of urbogenic soils beneath introduced ornamental tree and shrub species in urban areas of Burgas and Sozopol along the Southern Black Sea coast of Bulgaria. Soil samples were collected under Ligustrum lucidum W.T.Aiton, Magnolia liliiflora ‘Nigra’, Musa paradisiaca L., Nerium oleander L., Photinia × fraseri ‘Red Robin’, Pinus pinea L., Prunus serrulata ‘Kanzan’ and Trachycarpus fortunei (Hook.) H.Wendl. from two soil layers during spring, summer and autumn. The abundance and composition of the main microbial groups, total microbial count, mineralisation coefficient, cellulase and catalase activities, soil pH, humus content, temperature and moisture were determined. The microbial status showed pronounced spatial differentiation and a general decrease in total microbial abundance with depth. The highest total microbial count was recorded under N. oleander, whereas the lowest values were found under T. fortunei. Non-spore-forming bacteria dominated the microbial community, followed by bacilli, while actinomycetes and filamentous fungi were less abundant. Seasonal dynamics of total microbial count and enzyme activities showed higher values in autumn at most sites, followed by spring, whereas summer maxima were observed in the surface soil layers at two sites under favourable soil moisture conditions. Two-way analysis of variance showed that season did not significantly affect the analysed parameters, whereas soil depth significantly affected total microbial count, cellulase and catalase activities. Cellulase activity was higher in the surface layer and slightly increased in autumn at most sites, whereas catalase activity followed a similar spatial pattern. The mineralisation coefficient varied considerably among sites and was not directly related to total microbial abundance. Spearman correlation analysis identified humus content as the factor most strongly associated with microbial abundance and enzymatic activity. Overall, the results confirm the value of combining microbiological, enzymatic and physicochemical indicators for assessing the biological quality of urbogenic soils.

Received: 01 July 2026 / Accepted: 26 July 2026 / Available online: 10 August 2026

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This study aimed to compare the geographical distribution, ecological characteristics and phenological behaviour of forests dominated by Picea abies (L.) H.Karst. and Abies alba Mill. in Bulgaria, combining data from the National Forest Inventory and remote sensing. Ecological variables such as altitude, latitude, longitude, aspect, and slope were analysed to characterise species- specific habitat preferences. Phenological events, including the start of the vegetation period (SVP), the end of the vegetation period (EVP), and the length of the vegetation period (LVP), were also compared. The results indicated that in Bulgarian forests, P. abies dominates significantly more stands than A. alba. Both species are mainly found in the middle mountain zone, but the average altitude of spruce forests is 1507.6 ± 170.8 m, while that of fir forests is notably lower at 1371.1 ± 164.7 m. Both species favour sloping terrain, with fir tolerating steeper slopes (17.8° ± 7.2°), whereas spruce is more common on moderate slopes (14.8° ± 6.2°). They prefer shady exposures, though spruce shows greater tolerance to sunny conditions (61.5 %/38.5 %), while fir is more restricted to shaded exposures (77.7 %/22.3 %). P. abies begins its active vegetation period (SVP) early (~10 April ± 13.7 days), whereas A. alba delays SVP by over a week (~18 April ± 9.9 days). EVP also occurs earlier in spruce forests (~24 September ± 12.5 days), while in fir forests it is delayed by more than a week (~3 October ± 10.8 days). As a result, in both spruce and fir forests, LVP lasts approximately 167.2 ± 20.3 days. These findings enhance our understanding of the ecological and phenological differences between the two conifers and can be utilised to improve the efficient, evidence-based management of forests dominated by these species in Bulgaria, which may be important for addressing the challenges posed by climate change.

Received: 19 June 2026 / Accepted: 31 July 2026 / Available online: 12 August 2026

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.

Earthworms serve as vital bioindicators of soil health and are significant regulators of soil structure and organic matter dynamics in terrestrial ecosystems. In the face of intensifying an thropogenic pressures on soils and global climate, earthworm populations are increasingly vul nerable to the strains imposed by agriculture, mining, and deforestation. This study aimed to characterise earthworm assemblage structure across Guyana and to evaluate the influence of bi ogeographical, climatic, and edaphic factors on earthworm communities and ecotype distribution. Earthworms and soil samples were collected from 60 sites. Earthworms were methodologically dissected to aid in their identification, and soil samples were analysed for 16 parameters. A total of 68 morpho-species of earthworms from 8 families were identified. Of the four biogeographical re gions, the Highland Region exhibited the highest diversity, species richness and abundance. Sta tistical analysis revealed that soil, habitat and biogeography significantly influenced earthworm abundance and distribution of ecotypes. Soil analysis revealed that earthworm abundance was significantly correlated with soil calcium (R2 = 0.07, p = 0.006), phosphorus (R2 = 0.06, p = 0.006) and iron (R2 = 0.05, p = 0.016). Endo-anecic abundance was negatively correlated with calcium (-1.6) and iron (-1.8) and anecic abundance was positively correlated with phosphorus (+1.1) and negatively correlated with calcium (-1.1). Multivariate analysis revealed that soil type (R2 = 0.39, p < 0.001), habitat type (R2 = 0.19, p = 0.011) and geography (R2 = 0.16, p < 0.001) were the most significant drivers of the ecotype composition of earthworm communities. These findings provide a critical baseline for understanding the edaphic and climatic filters that shape soil biodiversity in the Guiana Shield and reinforce the sensitivity of specific ecotypes to land-use changes.

Received: 07 April 2026 / Accepted: 11 August 2026 / Available online: 24 August 2026

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.

Regular maintenance of spatially distributed urban parks requires municipal vehicles and maintenance teams to travel between a central depot and multiple service locations. When these routes are planned manually, unnecessary travel may increase fuel consumption, operating costs and CO2 emissions. The case study focuses on the planning of municipal park-maintenance trips in Sofia, Bulgaria. Seven large parks, served from one depot, were included in the analysis. Their service requirements and time windows were incorporated into a multi-objective vehicle routing model. The calculations also accounted for the length of the working day, travel costs, and the estimated CO2 emissions of the diesel vehicles. The optimisation was implemented in Python using Google OR-Tools and compared with a manually planned baseline scenario. Under the tested scenario conditions, the optimised solution indicates an approximate 20 % reduction in total travel distance, travel time, fuel consumption, and CO2 emissions. The number of active vehicles required for the selected daily maintenance tasks was also reduced from three to two. A standard vehicle routing approach was modified to reflect the operational and environmental aspects of municipal park maintenance. It may also be suitable for planning other municipal services, provided that the necessary local information is available.

Received: 29 June 2026 / Accepted: 25 August 2026 / Available online: 04 September 2026

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.

Bamboo is a rapidly renewable resource with considerable potential for biomass production and carbon sequestration. Therefore, site species-specific allometric models are necessary for reliable biomass estimation in individual species. This study aimed to develop and evaluate site species-specific allometric equations for estimating the culm biomass of four dominant tropical bamboo species (Bambusa vulgaris Schrad. ex J.C.Wendl., Dendrocalamus asper (Schult. & Schult.f.) Backer, Gigantochloa apus (Schult.f.) Kurz ex Munro, and Gigantochloa atter (Hassk.) Kurz ex Munro) on Lombok Island, Indonesia. Field data were obtained through an inventory of bamboo culms followed by destructive sampling based on diameter class. Culm diameter, culm height, and number of internodes were assessed as predictor variables using power-function models. Model performance was evaluated using the coefficient of etermination (R2), the Akaike Information Criterion (AIC), and the root mean square error (RMSE). Diameter was the most consistent predictor across the four species, while culm height and number of internodes contributed differently among species. The selected allometric models were species-specific: B. vulgaris (Y = 0.036·D1.548H0.961), D. asper (Y = 0.107·D2.162), G. apus (Y = 0.021·D1.261·H1.254) and G. atter (Y = 0.476·D2.705·R–0.792). The developed equations provide a practical and non-destructive method for estimating biomass at the individual culm level. When combined with data on stand density, diameter distribution, and carbon fractions, these equations can support further research on biomass and carbon stock estimates per hectare.

Received: 16 December 2025 / Accepted: 18 September 2026 / Available online: 15 October 2026

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.