A mycological survey on fungal diversity following the planned construction of hydropower plants in the Upper Neretva valley took place from 31. 5. to 4. 6. 2023 near Ulog, Bosnia and Herzegovina. The species diversity of fungi in this area was investigated for the first time. A fruitbody-based approach of fungi visible to the naked eye or using a hand lens was performed at four study sites. In total, 102 fungal species were recorded. Out of these, 10 species (Cerinomyces aeneus, Glyphium elatum, Kurtia macedonica, Ophiocordyceps stylophora, Orbilia lentiformis, Patinella punctiformis f. quercina, Perenniporia narymica, Proliferodiscus tricolor, Triblidium caliciiforme, Xerombrophila crystallifera) are new to the country to our knowledge. Other interesting records include Porotheleum fimbriatum, Crustomyces subabruptus, Guepiniopsis buccina, Elaiopezia polaripapulata or Perrotia flammea. The presence of dead wood supported a high number of wood-inhabiting species. The number of new and rare species recorded during the survey indicates a considerable research and conservation potential of the Upper Neretva valley.

The Balkan Peninsula is considered to be a biodiversity hotspot, hosting a particularly high number of endemic species. Despite increased faunistic research in recent decades many areas remain poorly investigated, particularly regarding the aquatic entomofauna. The order Plecoptera, for instance, is strongly associated with cold, well-oxygenated mountain rivers and is known for its high sensitivity to environmental change. Consequently, stoneflies serve as valuable bioindicators in environmental monitoring. Similarly, the order Trichoptera includes many species with high habitat specificity, which are vulnerable to habitat degradation. A comprehensive understanding of the region's species inventory is essential, not only to deepen the knowledge about the distribution and habitat preferences of endemic and rare species, but also to assess what is at stake in case of significant environmental changes, such as those caused by hydropower development. To address these gaps in our knowledge, faunistic surveys focusing on Plecoptera and Trichoptera were conducted in 2022 and 2023 along the upper reaches of the Neretva River and its tributaries Krupac, Ljuta, and Jezernica as well as smaller, unnamed brooks within the catchment. Here we report the results from 2023 and compare them to the data published in 2022; both surveys conducted as part of the Neretva Science Week. We aim to contribute to the broader understanding of species diversity, distribution, and abundance of Plecoptera and Trichoptera in this area.

The upper course of the Neretva River, located in the rugged landscapes of Bosnia and Herzegovina (BiH), hosts a unique and largely unexplored ecosystem with significant biodiversity. This study aims to document the spider (Araneae) species inhabiting this region, including the Neretva’s wider catchment area, Nevesinjsko polje, and the Vranjača cave. Using various sampling methods, we identified 84 spider species from 72 genera and 22 families, with 50 (60%) species reported in BiH for the first time. Notable findings include the abundant Piratula knorri (Scopoli, 1763) (Lycosidae), and cave-dwelling species such as a region endemic Parastalita stygia (Joseph, 1882) (Dysderidae) and Lepthyphantes leprosus (Ohlert, 1865) (Linyphiidae). Our results emphasise the importance of this understudied region for spider biodiversity and underscore the need for ongoing research to enhance faunistic knowledge and inform conservation efforts in BiH.

The extent of temperate old-growth forests in temperate Europe is diminishing as a result of anthropogenic pressures, despite a mandate from the European Union (EU) calling for their strict protection under the Biodiversity Strategy for 2030. However, the exact extent of old-growth forests is currently unknown due to insufficient mapping, particularly in the EU candidate countries in the Balkans. Using a combined approach of dendrochronology and visual observations of old-growth structural indicators, this investigation was the first rapid survey of the forests of the Upper Neretva River in Bosnia and Herzegovina. Ten forest patches were sampled over the course of seven days. We note high heterogeneity in forest types, with a distinct gradient from the riparian zone to the upper slopes of the valley. Historical human activities, particularly coppicing and clearance for grazing pastures, were perceivable in many locations. However, through utilising visual observations and dendrochronological dating, we can estimate the abandonment of these activities over a century ago, which has resulted in a landscape rich in different habitat types, specifically large old trees essential for biodiversity. We identified the old-growth lichen indicator species Lobaria pulmonaria throughout the study area. Moreover, small patches of both Fagus sylvatica and Quercus spp. potential old-growth forests were present. We therefore recommend a moratorium on logging in the region to preserve these ecosystems as stipulated in Green Agenda for the Western Balkans – a key component of EU integration.

To gain a clearer picture on large carnivores in the Upper Neretva region we exclusively focused on recording evidence of brown bear (Ursus arctos), grey wolf (Canis lupus), Eurasian lynx (Lynx lynx) and wild cat (Felis silvestris) presence in the field. For the Neretva Science Week 2023, the research area stretched over the Upper Neretva, the Ljuta and the Zalomka river. Focusing on the Upper Neretva valley, we investigated 87 km of transects and installed camera traps in the predefined focus area. Considering the short research time, we used a participatory approach to complement our data. Two indications of the presence of lynx in the area could not be confirmed within the survey week. With a total of 49 large carnivore records collected, we were able to confirm the presence of brown bear, grey wolf and wild cat for the Upper Neretva Valley, with wolf presence recorded up until Jezero. Bear presence was also confirmed for the Zelengora plateau and close to Nevesinje, while the presence of both species could be confirmed for the Ljuta river and for the Ulog dam reservoir before intense logging and filling.

This study investigates soil biodiversity in agricultural landscapes and focuses on the Nevesinje field in Bosnia and Herzegovina, which was sampled as part of the Neretva Science Week 2023. Soil microarthropods, including mites and springtails, play an important role in ecosystem health through nutrient cycling and organic matter decomposition. Using separate approaches — morphological techniques with the QBS-ar index and metabarcoding of DNA extracted from soil samples — we investigated the diversity and abundance of soil microarthropods at different sites. Our results showed that the arable field had the highest abundance of soil microarthropods, especially Acarina and Collembola, while the orchard had the lowest abundance but the highest QBS-ar value, which reflects higher soil quality according to the QBS-ar index. Insects (Insecta) dominate with 68.6% of identified taxa, followed by arachnids (Arachnida) with 20.2%. The arable field next to the Zalomka River showed the highest taxonomic richness. The area faces imminent threats from the proposed dam construction, which could alter the hydrological dynamics and integrity of the habitat. Continued monitoring and further sampling are important to assess the ecological impact and develop conservation strategies to maintain soil biodiversity amid developmental pressures.

This study investigates the riparian forest and scrub vegetation along the Zalomka and Upper Neretva rivers in Bosnia and Herzegovina (BiH). Despite the ecological significance of these rivers’ riparian zones, they remain underexplored, particularly regarding their floristic composition and ecological dynamics. We conducted a short-term phytosociological study in June 2023, using the Central European phytosociological method to collect and analyze 17 relevés from these riverine environments. Statistical classification identified five ecologically and floristically distinct clusters, ranging from pioneer scrub communities dominated by Salix eleagnos and Salix purpurea on gravel bars, over riparian forests on finer sediment dominated by Salix alba and/or S. euxina and Alnus rohlenae, to Salix eleagnos scrub communities with diverse mesophilous and thermophilous species. The study provides a preliminary syntaxonomical framework, assigning these clusters into relevant alliances. The findings highlight the need for further research to refine the classification and support the conservation of these unique riparian habitats, several of which are listed in the EU Habitats Directive. The study contributes to a better understanding of riparian ecosystems in the Dinaric Alps, offering insights into their conservation and management.

Between 1st and 6th of June 2023 we conducted floristic research on several sites in the upper Neretva River valley and the Zalomka River at Nevesinjsko Polje. We recorded 935 taxa in total; 898 plant species, including 126 bryophytes, were found at 52 localities in the upper Neretva River valley, and 200 plant species, including 32 bryophytes, at 11 sites in the Zalomka River valley. Among the registered species, 39 taxa are endemic to the Balkan Peninsula, 56 are listed in the List of endangered and rare taxa of Bosnia and Herzegovina, 27 in the Red list of the Federation of Bosnia and Herzegovina, and 95 taxa are protected in the Republic of Srpska. We registered also several new species for the flora of Bosnia and Herzegovina. Among Angiosperms these were Barbarea intermedia, Lamium hybridum, Myosotis sicula, Poa ursina and Salix phylicifolia, and among bryophytes Fissidens gracilifolius, Grimmia dissimulata, Plagiomnium ellipticum, Schistidium robustum, Sphenolobus minutus, Tortella fasciculata and Tortella pseudofragilis. Our study reveals the high nature conservation value of the upper Neretva and Zalomka river valleys that should be protected for future generations. In addition, further systematic research of the flora of Bosnia and Herzegovina is needed.

The Blue Heart of Europe campaign keeps publishing updates about the development of hydropower projects on the Balkan peninsula. It is one thing to see a map of thousands of threats to hundreds of rivers, but it is another thing to actually witness when one river gets lost before your eyes. In an act of stubbornness and unbroken optimism, despite ongoing construction of hydropower infrastructure for Ulog and Upper Horizon projects, the Blue Heart of Europe´s Scientists for Balkan Rivers Network once more organised a Science Week at the Neretva River. Between 30 May and 7 June 2023 almost 70 scientists and students from 17 countries and a once more diversified array of scientific disciplines joined forces to expand our knowledge on the biodiversity of the Neretva River catchment. Our mission was to document the biodiversity of the river, its hidden tributaries, underground rivers, mountain springs and the terrestrial valley sides. The 11 contributions published in this second special issue of Natura Sloveniae dedicated to the Neretva demonstrate once again the extraordinary biodiversity residing in this remote part of Europe. The many documented species encourage us to keep fighting for this exceptional natural heritage in spite of all difficulties.

In early June 2023, we studied the Lepidoptera fauna of the upper course of the Neretva River, the valley of the Zalomka River in Nevesinjsko Polje and the Morina plateau between the two. In total, we registered 237 species, 63 butterflies and 174 moths. We found 53 butterfly species in the area of the Upper Neretva River, 37 in Nevesinjsko polje and five on the Morina plateau, along with 156, 40 and 20 moth species, respectively. In this study, we increased the total number of registered Lepidoptera species for the area, from 251 found in the same region during Neretva Science Week 2022, to a total of 414 (93 butterflies and 321 moths). Eight species have the status of Near Threatened and one is categorised as Data Deficient according to IUCN Red List of Threatened Species. Two species are listed as Vulnerable in the Red List of the Federation of Bosnia and Herzegovina and three species are listed on the Annex II of the EU Habitats Directive. Our findings present a much-needed basic knowledge on Lepidoptera of the region, which is important for conservation activities.