Issues

Abstract

Forest soil is a key component of mountain ecosystems, providing water storage, nutrient cycling, carbon sequestration, and biodiversity support. This study assessed essential physical and chemical parameters related to the health status of Cambisols in mature Norway spruce (Picea abies L.) stands within Pirin National Park, Southwestern Bulgaria. Ten soil profiles were sampled across an altitudinal range of 1386–1790 m a.s.l. Soil depth varied between 30 and 67 cm, according to WRB (2022) and regional classification criteria, all were considered shallow, potentially limiting root development and water storage capacity. In the A horizon, pHH2O ranged from 4.1 (very strongly acidic) to 6.2 (slightly acidic), while CEC was high to very high (11.96– 33.52 cmol(+)·kg-¹), largely dominated by exchangeable Ca²+. Base saturation varied from 61 % to 99 % in surface horizons, but unsaturated conditions (<50 % BS) occurred in 50 % of the Bw horizons. Organic carbon content in the A horizon ranged from 25.81 to 63.36 g·kg-¹, with C/N ratios from 8 to 15, and available water holding capacity from 32 % to 68 %. These results indicate that although the soils are well supplied with organic matter and have favourable porosity and bulk density, acidity, low base saturation in some profiles, and dominance of chemically inactive texture fractions (sand and silt) may constrain soil health. The findings provide a regional baseline for soil health assessment in Pirin National Park, with practical implications for sustainable forest management and conservation planning in other mountainous protected areas.

Received: 16 July 2025 / Accepted: 22 September 2025 / Available online: 29 September 2025

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

Abstract

‘Golak’ hill and Karkariya ridge of the Western Rhodope Mts. are subjected to high anthropogenic load from various activities (now and in the past). However, a number of protected species live there, which procured for targeted monitoring. Between March 2023 and June 2024, we surveyed nine sampling plots via 54 pitfall traps and manual collecting of material. Here we present the data obtained about one of the indicative groups of animals, the ground beetles (Coleoptera: Carabidae). A total of 3229 specimens from 92 species were collected. Calathus distinguendus Chaudoir, 1846 and Carabus convexus Fabricius, 1775 were eudominants; Carabus montivagus Palliardi, 1825 and Laemostenus cimmerius (Fischer von Waldheim, 1823) were dominants. Carabus convexus was euconstant, collected in all sampling sites. Beetles belonged to 22 categories from the five faunal types of Bulgarian carabids, as the European-Asiatic (30 species; 33 %) and Mediterranean (21; 23 %) complexes prevailed. We found relatively low number of winged beetles (57 %), which is comparable only with typical montane habitats. The established ratio between the life forms classes (54 % Zoophagous and 46 % Mixophytophagous species) is close to the typical for the meadow steppes from the Forest-steppe zone of Eurasia. In relation to their humidity preferences, mesoxerophilous (38 %) and mesophilous (28 %) carabids predominated. Mathematical processing showed that: 1) there was a clear separation of the forest habitats, based on two indicator species; 2) overgrazed habitats formed another well-defined group; 3) in addition to the habitat type separation, the ecotone edge effect and ecological catastrophic effect were both present, as well.

Received: 05 July 2025 / Accepted: 21 September 2025 / Available online: 29 September 2025

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

Abstract

Botanical gardens and arboreta play an important role in plant science research and biodiversity conservation. In recent decades, the social role and cultural functions of botanical gardens,as urban green infrastructure elements and tourist attractions, have influenced their design. The University of Forestry’s Petrohan Arboretum serves primarily as an educational resource. In addition, it plays a key role in scientific research on tree species’ responses to climate change and their adaptation to the local environment. The beautiful nature makes the campus attractive as a centre for workshops, seminars, and green schools. It has great potential for further development, particularly as an attractive destination for educational tourism. The aim of this research is to develop a contemporary landscape design concept for the rehabilitation of the University of Forestry’s Petrohan dendrological park and its transformation into both a functional hub for education and research, and an inspiring green space that enhances the landscape’s aesthetic value while promoting biodiversity. The preliminary studies involved data collection and analysis of the current condition of vegetative and non-vegetative elements. The key design principles for the rehabilitation of the Arboretum were: (1) enhancing biodiversity; (2) providing engaging educational opportunities; (3) developing a sustainable design. These principles emphasise the importance of creating enriching, multifunctional nature-based open spaces that not only support biodiversity and scientific research, but also serve as educational and recreational resources for students and the community. A master plan following the new concept of functions and structural planning has
been designed based on the site analysis

Received: 30 June 2025 / Accepted: 20 September 2025 / Available online: 29 September

2025 Open Access: This work is distributed under the Creative Commons Attribution 4.0

Abstract

An open-field study was carried out in 2023–2024 at the Institute for Roses and Aromatic Plants – Kazanlak, aiming at evaluation of herbicide weed control in lavender plantation (Lavandula angustifolia Mill.) cultivar ‘Yubileina’. Herbicide efficacy and selectivity of BeFlex (500 g·L-1 beflubutamid) and Battle Delta (400 g·L-1 flufenacetate + 200 g·L-1 diflufenican) were determined, applied on soil in two concentrations before beginning of lavender vegetation. The effect of the herbicides on weed infestation and on lavender growth and development was followed. Results analyses show that BattleDelta successfully controls annual dicotyledonous and monocotyle¬donous weeds (Chenopodium album L., Polygonum aviculare L., Veronica agrestis L., Sonchus oleraceus L., Alopecurus myosuroides Huds., Poa annua L.). The soil activity of the herbicide persists up to the 60th day after treatment. That makes it possible to eliminate the competitive impact of weeds on lavender growth after beginning of growing. BeFlex exerts effective action on annual dicotyledonous weeds reducing their number by 14–17 % compared to the control. No phytotoxicity was observed after herbicide application. On the contrary, lavender fresh mass and oil yields were higher in treated area than from the untreated control.

Received: 26 June 2025 / Accepted: 09 September 2025 / Available online: 20 September 2025

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

Abstract

Subalpine willow shrublands are locally distributed in Vitosha Mt. and are dominated by low-growing willows (Salix lapponum L., Salix waldsteiniana Willd.). During the 2021–2022 field seasons, 21 relevés were collected following the Braun-Blanquet approach. Complete informa¬tion on the species composition and abiotic characteristics of the environment (elevation, aspect, slope, soil depth) in all sample plots was collected. Diagnostic, constant and dominant species were identified for all established syntaxa. The aims of this study are: (1) to establish the syntaxonomical diversity of subalpine willow shrub vegetation on Vitosha Mt., Bulgaria; and (2) to reveal the species composition and vegetation structure of the established syntaxa. For the first time, the distribution of 2 associations representing subalpine willow shrublands has been established for the vegetation of the country – Salicetum lapponum Zlatník 1928 and Salicetum waldsteinianae Beger ex Oberdorfer 1978. Association Salicetum lapponum is dominated by the downy willow Salix lapponum. It reaches 1–1.5 m height and covers 85–100 %. Association Salicetum wald¬steinianae is dominated by Salix waldsteiniana, which covers 95–100 %. From ecological point of view, ass. Salicetum lapponum occupied wetter habitats with acidic soil reaction and lower nutrient content, whereas ass. Salicetum waldsteinianae is found in less acidic microhabitats, with higher nutrient content. Habitats of both willows are listed in the Habitat Directive 92/43/EEC (4080 Sub-Arctic Salix spp. scrub), Annex I of the Bulgarian Biodiversity Law and the Red Data Book of the Republic of Bulgaria. Main pressures and threats affecting those phytocoenoses are climate change and especially changes in precipitation regimes, natural succession and the influence of human activities.

Received: 01 July 2025 / Accepted: 07 September 2025 / Available online: 20 September 2025

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

Abstract

Phenological observations are among the most important for identifying the responses of fruit trees to climatic conditions of their habitat. Temperature changes have most significant influence on the phenology of fruit trees, particularly on flowering. This study aimed to monitor the pheno¬logical development of six sweet cherry cultivars grafted onto Maxma 14 rootstock. Phenological phases, including bud swelling (BBCH 51), full flowering (BBCH 65), and fruit harvest maturity (BBCH 87), were monitored to determine the duration of flowering, length of growing season, and the period from full flowering to fruit harvest maturity. Changes at the beginning of the growing period, occurring 2 to 8 days earlier in the second reporting year, were observed for most of stud¬ied cultivars. Deviations were also noted in the phenological phase BBCH 65, which occurred 4–8 days earlier and was 2–5 days shorter in the second year. This study demonstrated that temperature changes significantly impacted both duration and timing of the flowering and growing seasons in sweet cherries.

Received: 26 June 2025 / Accepted: 02 September 2025 / Available online: 20 September 2025

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

Abstract

Backcountry skiing and touring have gained significant popularity in recent years, with numerous accidents occurring annually worldwide. Bulgaria’s Pirin Mountains have experienced similar trends, highlighting the urgent need for tools that enhance public awareness of avalanche-prone terrain. The Avalanche Terrain Exposure Scale (ATES) offers a systematic approach to classifying terrain based on its potential avalanche exposure, relying exclusively on static terrain and vegetation characteristics. While early ATES maps were manually produced by experts, recent advancements, such as machine learning-based approaches, have enabled scalable and accurate automated ATES (AutoATES) mapping over larger areas. A critical component of AutoATES classification involves modelling the protective effect of forests, which requires information on forest structure. Recent applications have incorporated remote sensing-derived forest structural parameters, such as percent canopy cover (PCC), to approximate forest protective effects in AutoATES model chains. In this study, we applied a recently developed machine learning framework for AutoATES classification to generate ATES maps for a study area in the Pirin Mountains, focusing on the effect of different PCC datasets on final and intermediate results of the model chain. Specifically, we tested a few forest cover scenarios: (1) the Copernicus Tree Cover Density product as a baseline, (2) a treeless simulation with PCC set to 0%, and (3) two alternative PCC estimates derived from RapidEye satellite imagery and information from digital elevation models. Our findings indicate that forests significantly reduce avalanche terrain exposure in the study area and that variations in PCC estimation can substantially alter the extent and distribution of different ATES classes. Notably, the second investigated RapidEye-based PCC estimation approach provided improved identification of forest gaps and dwarf mountain pine (Pinus mugo Turra) compared to the first, resulting in more accurate ATES maps in those respective areas.

Received: 30 June 2025 / Accepted: 01 September 2025 / Available online: 20 September 2025

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

Abstract

The objective of this study was to enhance the analysis of vegetation information using the normalised difference vegetation index (NDVI) through remote sensing data. NDVI values were correlated with ground measurements to derive insights into vegetation health and productivity. The experiment focused on courgette cultivation, where NDVI was measured at full growth using a Trimble GreenSeeker handheld sensor. Various nitrogen and phosphorus fertilisers were applied, including ammonium nitrate, phosphates, and polyphosphates. The highest NDVI value achieved was 0.802 with ammonium nitrate (nitrogen treatment) lacking phosphorus. On a polyphosphate background, the nitrogen source with the highest NDVI was KSC, yielding 0.800. With an orthophosphate background, KSC produced the best NDVI of 0.815. Its highest values were consistently linked with the orthophosphate background, and these results were statistically validated. A strong correlation coefficient (r = 0.72) was observed between NDVI and courgette yield. The integration of NDVI into our analytical approach significantly refined the analysis of vegetation data, yielding more precise insights.

Received: 26 June 2025 / Accepted: 29 August 2025 / Available online: 15 September 2025

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

Abstract

Representatives of Cervidae family are important bioindicators of the environmental pollution caused by various heavy metals. Significant amounts of toxic elements can accumulate in tissues and organs, particularly in the liver and kidneys. The study of accumulation levels can provide valuable information about the state of ecosystems and potential risks to human health, especially for areas with developed intensive industrial activity or proximity to pollution sources. The aim of this review is to summarise and compare reported data (2000–2024) on copper (Cu), mercury (Hg), and arsenic (As) accumulation in three edible organs (muscle, liver, and kidney) of the following members of Cervidae family: Roe deer (Capreolus capreolus L., 1758), Red deer (Cervus elaphus L., 1758), and Fallow deer (Dama dama L., 1758), and to discuss bioaccumulation trends and the potential health risks posed by the consumption of these products. The literature findings were compared with the established permissible limits according to European and international regulations. The possible health hazards associated with the consumption of meat and by-products, accumulation pathways, and organs affected by toxic damage were also examined. This information is essential for assessing the safety of wild game meat and by-products for human consumption, as well as for developing effective strategies for environmental protection and management of wild populations. In most studies, the reported levels of Cu, Hg, and As in deer meat, liver, and kidneys did not exceed the established safety thresholds. However, isolated cases of elevated concentrations, especially in the liver and kidney tissues from polluted areas, underscore the necessity of regular monitoring and cautious consumption.

Received: 18 July 2025 / Accepted: 29 August 2025 / Available online: 15 September 2025

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

Abstract

In 2023, during scientific expeditions in the regions of Shumen, Ruen, Kuklen, Osmar, Varna and Aytos, part of a project for preservation of local genetic resources, nine local cherry cultivars and forms were discovered. The aim afterwards was to make a pomological description and identify the cultivars, as well as determining biometric parameters and ripening dates. Specimens were mapped with GPS coordinates in the project’s database, the ripening period of the fruits was determined, as well as their pomological characteristics. Biometric analyses of fruit and stones were performed and compared to the standard cultivars ‘Van’ and ‘Bigarreau Burlat’. The earliest ripening fruits are of specimen SS-08 on 8 June, and the latest ripening are of SM-29 is on 26 June. Specimen SS-06 had the highest fruit weight 6.09 g from the discovered cherry forms, and SM-29 had the lowest fruit weight 1.31 g. The stone weight ranged from 0.15 g in SM-29 to 0.36 g in SS-06. The shortest stalk was measured for SS-09 at 22 mm and the longest for SS-08 at 62 mm.

Received: 25 June 2025 / Accepted: 22 August 2025 / Available online: 27 August 2025

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

Abstract

This paper presents results of an experimental study of a FAE SSM/HP 250 forestry tiller, powered by Fendt 939 Vario tractor with nominal power of 265 kW, used for soil preparation of open areas designated for field-protection establishment of forest belts in the Dobrudzha region in Northeastern Bulgaria. The influence of the mechanical composition and hardness of the soil, the tillage depth, and the tiller rotor rotational frequency on the operational performance and fuel consumption were studied. The experiments were conducted in open forest areas, with different mechanical composition and hardness of the soil. The experimental plots are located on clay-sandy soils with an average hardness of 345 kPa, sandy-clay soils with hardness 690 kPa and clay soils with hardness 2100 kPa. As a result of the study, functional mathematical models were developed to determine the operating performance and fuel consumption of the tilling unit, depending on the rotor rotational frequency, soil mechanical composition and hardness, and tillage depth. These results were used to determine the optimal rotor speed of the tiller based on soil type and tillage depth.

Received: 18 June 2025 / Accepted: 19 August 2025 / Available online: 25 August 2025

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

Abstract

Thyme is a perennial herb from Lamiaceae family, particularly valued for its essential oils, which contain bioactive compounds with significant therapeutic and culinary properties. The oil composition varies significantly due to factors like genetic diversity and geographical distribution, resulting in distinct chemotypes. Thyme cultivation offers a valuable alternative to harvesting natural resources which disturb and diminish biodiversity and natural sustainability. A comparative field study was set up in 2021 at the Agricultural Experimental Station at the Eastern Rhodopes in town of Kardzhali with thyme species. Three genotypes were included in the study: a thymol-type cultivar ‘Deutscher Winter’ (Thymus vulgaris L.), and two Bulgarian cultivars: citral-type ‘Slava’ (Thymus sibthorpii Bentham.) and geraniol-type ‘Pagane’ (Thymus marcshallianus Willd.). Phenological and biometrical indexes were gathered and analysed, data on oil content and mass productivity were also presented. In the Eastern Rhodopes full bloom period is cultivar-dependent and occurs as follows: 10–20 May for ‘Deutscher Winter’ thyme, 1–10 June for ‘Slava’ and 5–20 June for ‘Pagane’. At the third year of thyme cultivation, the highest fresh mass per plant was gathered from ‘Deutscher Winter’ variant (445 g), followed by ‘Slava’ (345 g) and ‘Pagane’ (219 g). The highest FW/DW ratio was evaluated for ‘Slava’ (1:4). In the first years, fresh mass yield harvested per hectare varied significantly: 10–13 t·ha-1 from ‘Deutscher Winter’, 6–13 t·ha-1 from ‘Slava’ and 2–7 t·ha-1 from ‘Pagane’. Essential oil harvest quantities followed fresh mass yield – the highest oil yield was recorded for ‘Deutscher Winter’ (19.6–24.5 kg·ha-1), followed by ‘Slava’ (12.8–32.8 kg·ha-1) and ‘Pagane’ (8.1–17.3 kg·ha-1). Oil content was dependent on the year of cultivation. The highest amount was recorded for ‘Pagane’, followed by ‘Slava’ and ‘Deutscher Winter’.

Received: 30 June 2025 / Accepted: 18 August 2025 / Available online: 22 August 2025

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

Abstract

The common walnut (Juglans regia L.) is widely distributed in Bulgaria, commonly cultivated in private gardens, along streets and intercity roads, and in orchards. It currently ranks third among fruit tree species in terms of cultivated area in the country. Walnut is also important in agroforestry systems, including alley cropping, silvopastoral, and forest farming. This study aimed at the early detection of alien insect species in Bulgaria. Field surveys were carried out in August and September 2024 in urban and suburban localities of southern Bulgaria where common walnut trees are established. Larvae and pupae of Carob moth Apomyelois ceratoniae (Zeller, 1839) were found in dry walnut fruits collected in areas of Belovo, Chernichevo, Chernomorets, Gorski izvor, Kapitan Andreevo, Lyubimets, Plovdiv, Purvomay, Simeonovgrad, and Svilengrad. This is the first report of A. ceratoniae as a pest of common walnut in Bulgaria. The species appears to be widely distributed and may be more prevalent than currently documented.

Received: 25 July 2025 / Accepted: 10 August 2025 / Available online: 18 August 2025

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

Abstract

The aim of the study was to perform a colorimetric assessment of eggshell colour variations in Common Pheasant (Phasianus colchicus Linnaeus, 1758) used for resettlement in Bulgaria. A total of 360 eggs were divided into five groups according to eggshell colour. Using a colorimeter, the colour characteristics were determined in the CIE L*a*b* colour space, and chroma (C) and the Shell Color Index (SCI**) were calculated. The highest lightness (L*) values were observed in the beige eggshells (68.62 ±1.62), while the lowest were found in the olive-green eggshells (55.89 ±0.49) (P < 0.001). Low negative mean values for the a* coordinate were observed only in the green eggs (−1.41 ±0.78), while low positive values were recorded for the other groups, reaching 6.8 ±0.93 for olive-green eggshells. Positive values were recorded for the b* coordinate, ranging from 13.96 ±0.80 (green) to 21.90 ±0.77 (beige), indicating a yellow spectrum position (P < 0.001). Shell Color Index (SCI**) had the lowest values for olive-green eggshells (−35.07 ±1.42) and the highest values for green eggshells (−53.07 ±2.17) (P < 0.01). The study revealed significant variations in the pigment distribution in the eggshells of the Common Pheasant, with differences in the colour index ranging up to 51.67 % between the maximum and minimum individual values. It is possible that these differences in eggshell colouration are linked to the genetic purity of the most widely bred subspecies of the Common Pheasant (Phasianus colchicus mongolicus Brandt, 1844) in the country’s game farms. Conducting a phylogenetic analysis of the population could shed light on this issue.

Received: 18 June 2025 / Accepted: 06 August 2025 / Available online: 18 August 2025

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Abstract

Large-scale natural disturbances in forest ecosystems drastically alter the light regime for residual saplings within the affected areas, placing their survival under considerable threat. Light acclimation of photosynthesis represents a key physiological mechanism for maintaining a positive carbon balance, thereby enabling plants to preserve their protective functions within altered environments. The aim of this study was to assess interspecific differences in photosynthetic light acclimation and carbon-use efficiency in saplings of three forest tree species – Fagus sylvatica L., Populus tremula L. and Acer platanoides L. – following large-scale natural disturbances. These species were selected due to their contrasting ecological strategies: the shade-tolerant F. sylvatica, the light-demanding pioneer P. tremula, and the moderately plastic A. platanoides. A comparative analysis of parameters, such as AMAX, RD, LCP, and LSP reveals pronounced species-specific responses, reflecting divergent functional–ecological strategies. These findings provide deeper understanding of the mechanisms underpinning light acclimation and offer valuable insights for adaptive forest management, particularly considering the increasing frequency and intensity of climate-induced disturbances. The results may support improved predictions of regeneration dynamics and species resilience under future forest conditions.

 Received: 23 May 2025 / Accepted: 04 August 2025 / Available online: 20 August 2025

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

Abstract

Ecological information about plant communities can contribute to better landscape design.
Grime’s CSR model, which categorises plant species as competitors (C), stress-tolerators (S), and ruderals (R), is fundamental to understanding plant community assembly. Seed size is a crucial trait that influences germination success and species establishment, especially when seeds are sown in situ. In landscape architecture, mulches are commonly used for sowing because they help retain soil moisture and suppress weed growth. This study investigates two main aspects in combination with different mulching substrates: (1) how CSR (competitor–stress-tolerator–ruderal) strategies influence species composition, and (2) how seed size affects initial germination. It also examines which adaptive strategies are associated with species that become dominant under specific mulch conditions. An experimental study was conducted using two types of mulch – organic (compost) and mineral (sand) – and three different seed mixtures containing perennial herbaceous plants. Species cover was assessed in the third year after sowing. Additional data on seed weight, adaptive strategy, and maximum species height were retrieved from published databases. The statistical analyses were performed using generalised linear models. The findings highlight the role of adaptive strategy in determining species dominance. The type of mulch affects the dominant adaptive strategy. Dominant plants in sand mulch had a higher R-score. In compost, the C-score was the highest, whereas in plots without mulch, the S-score prevails. Seed size also played a significant role in germination across various substrates. These results have important implications for species selection in wildflower meadow design. Understanding the interaction between adaptive strategy and mulch type can enhance the success of perennial plant communities by optimising species compositions. Planning the management of established wildflower meadows can also be aided.

Received: 27 May 2025 / Accepted: 21 July 2025 / Available online: 18 August 2025

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Abstract

Common Wood pigeon (Columba palumbus L., 1758) is a widespread species in Europe including Bulgaria, with increasing population trend. Understanding its diet is essential for assessing its ecological role and predicting responses to habitat changes. This study examines the feeding spectrum in autumn and winter of the species in Bulgaria based on crop content analysis of 54 specimens collected from 11 hunting areas between 2022 and 2024. A total of 21 dietary components were identified, including 17 plant and 4 animal taxa. The primary food resources were sunflower seeds, maize, and acorns, with seasonal variations in diet composition. The study confirms the opportunistic feeding behaviour of the Wood pigeon, influenced by food availability. While cereals and acorns remain staple components, molluscs and insects played a minor role. These findings contribute to a better understanding of the species’ feeding habits in Bulgaria and provide a basis for future ecological and conservation research.

Received: 13 May 2025 / Accepted: 13 July 2025 / Available online: 18 August 2025

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

Abstract

In the period 2020–2022 in the experimental field of the Research Institute of Mountain Stockbreeding and Agriculture – Troyan a research experiment has been conducted with the following species of perennial leguminous meadow grasses: birdʼs-foot-trefoil (Lotus corniculatus L.), hybrid clover (Trifolium hybridum L.), alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), white clover (Trifolium repens L.). The experiment aimed to monitor the composition of the structural fibre components of the forage cell walls average two-year period. The dry matter digestibility and energy nutritional value was determined. The legume crops studied were found to have different compositions of forage cell wall fractions. The forage mass of red clover showed the lowest content of neutral and acid detergent fibre (30.87 % and 21.49 %), and acid detergent lignin (8.11 %) and the highest dry matter digestibility (73.11 %). The alfalfa forage had the highest hemicellulose values (11.17 %) and that of hybrid clover had the maximum cellulose values (24.06 %). Good energy nutritive value was recorded by the forage of birdʼs-foot-trefoil and white clover.

Received: 05 May 2025 / Accepted: 03 July 2025 / Available online: 18 August 2025

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Abstract

A study has been conducted to identify burned areas in the region Otets Paisievo village in Plovdiv District, Bulgaria. The research aims at locating the burned areas and determining the degree of damage caused by a wildfire which occurred in the summer of 2024. Remote sensing and GIS methods were applied for the study. Various spectral indices (NDVI, MIRBI, NBR, NBR2, RBR, BAI, BAIS2) were generated using data from the Sentinel-2 satellite. The separability index (SI) was calculated, which showed the highest values for dMIRBI, dNBR2, dNBR and dBAIS2. Based on these four differential index differences, the burn area was determined and compared with data from the European Forest Fire Information System (EFFIS) and the local and national forestry sector. The results demonstrated a strong correlation with the actual burned area. Based on the analysis of spectral index values and the corresponding histograms, the study area was classified into four burn severity categories: unchanged, low, moderate, and high. The research indicates that for the surveyed area, indices based on shortwave infrared (SWIR) bands are effective in detecting and mapping forest fire burned areas.

Received: 10 May 2025 / Accepted: 27 June 2025 / Available online: 18 August 2025

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Abstract

This special issue of the Forestry Ideas is dedicated to the international scientific conference ‘A Century of Forest Knowledge: Education, Innovations, Challenges’, held to mark 100 years of university forestry education in Bulgaria. This event served as a significant academic forum for forestry researchers, practitioners, and policymakers. Given the unprecedented pressures facing forest ecosystems – from climate change and extreme weather events to prolonged droughts, wildfires, and other global challenges – the role of forest science and education has become more critical than ever. The conference placed strong emphasis on sustainable forest management, biodiversity conservation, ecosystem restoration, and the protection of old-growth forests. These themes reflect the urgent need for integrated, evidence-based approaches to forest management and conservation. The conference brought together a vibrant international community, featuring 116 scholarly contributions from 433 co-authors across 13 countries and over 30 academic and research institutions. We were also honoured to host participants from scientific organisations, governmental bodies, and non-governmental organisations, further underscoring the interdisciplinary and collaborative spirit that defines modern forestry science. The main thematic fields of the conference were: Climate change and forests; Ecosystem biodiversity, conservation and environmental restoration; Agriculture in mountainous and semi-mountainous regions; Forest disturbances and management challenges; Forest stand dynamics, growth and yield; Forest policy and key challenges; Forest operations and wood processing; Wildlife conservation and management;
Landscape architecture.

Received: 11 August 2025 / Accepted: 11 August 2025 / Available online: 18 August 2025

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