During ongoing bryological surveys conducted in the Mt. Papuk, two significant sites, Sokolina Gosted and Svinjarevac, have been identified. These sites are characterized by unique acidophilic forests with a predominance of peat mosses on the forest floor. Sokolina Gosted represents the first documented locality in Croatia for four taxa: Andreaea rothii ssp. rothii , Grimmia donniana, G. montana , and Racomitrium affine . Furthermore, Buxbaumia aphylla and Dicranum spurium were observed for the first time at both Sokolina Gosted and Svinjarevac. Additionally, several extremely rare species have been reported at one or both locations, including Cynodontium polycarpon, Dicranum polysetum, Isopaches bicrenatus, Jungermannia pumila, Pleuridium acuminatum, Rhabdoweisia fugax, Syzygiella autumnalis and Ulota intermedia . Consequently, both locations serve as important bryological hotspots, exhibiting distinctive species assemblages within unique habitats relevant to Southeast Europe. While the significance of these sites in terms of bryophyte diversity is clear, the presence of the invasive species Campylopus introflexus underscores the necessity for ongoing research and monitoring efforts in the area.

Pondweeds, an important component of macrophyte vegetation, are influenced by various ecological factors of the aquatic ecosystem. In turn, pondweeds affect the nutrient and sediment dynamics and provide food and shelter for other organisms. As different species have specific environmental preferences and tolerances, they can serve as indicators of the ecological status of water bodies. Here, the ecological preference of the seven most frequent pondweeds in Croatia (Potamogeton berchtoldii, P. crispus, P. lucens, P. natans, P. nodosus, P. perfoliatus and Stuckenia pectinata) for chemical and physical water parameters was studied using 218 vegetation relevés and the accompanying water parameters. CCA revealed the main environmental gradients described by six parameters (chemical oxygen demand, total nitrogen, total phosphorus, electrical conductivity, dissolved oxygen and pH), while ecological responses of the species were further explored by GAMs. Potamogeton berchtoldii, P. lucens, P. natans and P. perfoliatus prefer clean, oxygenated, oligo- to mesotrophic water, and P. crispus and S. pectinata thrived in eutrophic water with low oxygen levels, while P. nodosus is a widespread generalist. The results of this study explain the distribution patterns of Potamogeton and Stuckenia species in Croatia, and add to the general knowledge on their role as bioindicators.

In Croatia, alkaline fens are rare and highly endangered ecosystems that rely on precipitation and mineral-rich ground water. They are characterized by extreme environmental conditions such as high soil moisture, low nutrients and oxygen availability. In this study we present plant (vascular plants and bryophytes) and soil invertebrate diversity (isopods, carabid beetles and ants), together with soil properties of the alkaline fen Dretulja River Valley, near the settlement Plaški, Croatia. Our objective was to discover whether plant and animal communities are specialized to this extreme habitat, the answer to which is of great value for biodiversity conservation. The unique fen conditions supported high plant diversity, including extremely rare and threatened plant species (e.g. the carnivores Pinguicula vulgaris, Drosera rotundifolia and Utricularia minor) and relic vegetation of dominantly Holarctic (e.g. Carex flava, C. lepidocarpa, C. rostrata, Parnassia palustris) and boreal elements (e.g. Scorpidium revolvens and S. scorpioides). Analysis of the Ellenberg-type indicator values of plant species demonstrates that the fen habitat is well-insolated, water-saturated, moderately alkaline and nutrient-poor. In contrast to plants, soil invertebrate diversity, particularly isopods and carabid beetles, was reduced due to the harsh environmental conditions. Only ants demonstrated any great capacity to tolerate extreme environmental stresses, although they were also low in abundance. Soil invertebrate communities were predominantly composed of hygrophilous to mesophilous species, typically associated with wetlands, meadows and open bogs. Notably, we recorded Asellus aquaticus, a freshwater isopod species, whose presence in the samples was likely due to being washed into traps during elevated water levels. Additionally, we recorded a tyrphophilous ant species Myrmica scabrinodis in the fen. Thus, the composition and structure of plant and invertebrate communities indicates that the fen's hydrological conditions remained well-preserved and to preserve great fen biodiversity it is essential to maintain these hydrological conditions.

Peatlands are among the most threatened habitats in Europe, particularly near the southern edge of their distribution in the Western Balkans. However, baseline data on their ecological condition are lacking in many countries, including Croatia. To provide a basis for effective conservation and management of these priority habitats, this study presents a comprehensive overview of habitat characteristics, main threats, and plant and invertebrate assemblages for 80 % of the known Croatian peatlands. Furthermore, we assess the conservation status of each peatland and analyse their similarities in terms of habitat condition, threat intensity and current management. Nearly two-thirds of the investigated peatlands were found to be in highly unfavourable conditions, with transition mires being especially vulnerable to advanced vegetation succession and hydrological degradation, typically caused by artificial drainage. In some Croatian peatlands, these processes have resulted in the loss of typical peatland plant species and may lead to local extinctions of rare tyrphophilous and stenotopic invertebrates. In line with our findings, we propose general guidelines for active peatland conservation measures, including restricting vegetation succession, improving hydrological conditions and minimizing anthropogenic impacts, which can be applied to other peatlands facing similar challenges. Targeted, site-specific management efforts will be essential to secure the long-term persistence of peatland habitats in Croatia and the wider region of the Western Balkans.

Silver lime is a thermophilic, calciphile species that thrives in xero-mesophilic forest communities. The westernmost edge of its natural distribution is Zrinska Gora Mountain in central Croatia, where it is found in almost all types of forest vegetation, albeit with varying frequencies. Its ecological optimum is in specific ravines and grooves, where it forms the mesophilic, relict broad-leaved ravine forest community Polysticho setiferi-Tilietum tomentosae. This research was conducted on two levels. Firstly, the communities of Zrinska Gora were analyzed as the westernmost edge of the natural distribution. Secondly, the ecology of the Tilia tomentosa communities in the western part of its distribution (Croatia, Bosnia and Herzegovina, Hungary, and Serbia) was observed. Analysis of Ellenberg-type indicator values for 74 communities from the western Balkans revealed a slight trend of decreasing thermophilicity and increasing acidophilicity toward the western edge of the distribution area. Silver lime peripheral populations on Zrinska Gora develop under unique ecological conditions. The soil reaction of all communities falls below the lower limit of the optimal range for its development, and the relict association experiences lower temperature values compared to the other communities. All in all, the results of this study provide insights into the adaptability of silver lime to climate change.

U članku se predstavljaju novi podaci za 22 vaskularne biljke (Anthyllis dalmatica, Carduus chrysacanthus, Centaurea alpina, Centaurea ceratophylla ssp. danielae, Ceratophyllum submersum, Cyclospermum leptophyllum, Dactylorhiza sambucina, Drimia maritima, Euphorbia hercegovina, Linaria microsepala, Neotinea lactea, Ophrys archipelagi, Op. lutea subsp. galilaea, Ophioglossum lusitanicum, Polygonum salicifolium, Pseudostellaria europaea, Quercus coccifera, Senecio viscosus, Silene vallesia subsp. graminea, Stratiotes aloides, Torilis nodosa i Utricularia minor), četiri mahovine (Blasia pusilla, Philonotis marchica, Rhodobryum ontariense i Ricciocarpos natans), jednu gljivu (Rhodophana nitellina) i 11 vrsta algi (kremenjašica) (Achnanthidium druartii, Amphora aequalis, Brachysira chiaruccii, B. paraexilis, B. styriaca, Gomphonema angusticephalum, G. supertergestinum, Halamphora bullatoides, Mayamaea ingenua, Planothidium fonticolanceolatum, Simonsenia maolaniana) u Hrvatskoj i susjednim zemljama (Bosna i Hercegovina i Crna Gora).

Context Floodplains play an important role in regulating regional water and nutrient cycles in riverscapes, also supporting high biodiversity. However, ecological requirements of aquatic macroinvertebrates in such habitats are still not sufficiently studied.Aims We analysed mayfly assemblages in two habitat types (near natural and anthropogenically disturbed) in a Danube floodplain.Methods Over a 2-year period, the mayfly nymphs were sampled at a total of 14 study sites in each season by using a benthos hand-net.Key results We recorded a low (five species) mayfly species richness. Owing to the reduced influence of the Danube River, i.e. the lower water level fluctuations and the greater habitat heterogeneity, the mayfly taxonomic and functional assemblage metrics were significantly higher in anthropogenically disturbed habitats than in near natural ones. Mayfly assemblages were correlated with higher macrophyte abundance and species richness, pH and water transparency, and lower oxygen and nitrate concentrations in the water.Conclusions Our results confirmed the high value of habitat heterogeneity for the conservation of aquatic macroinvertebrates in extreme habitats such as floodplains of large lowland rivers.Implications Those results can be used in planning management activities of freshwater habitats in protected areas.

Peatlands are unique ecosystems that differ significantly from other wetlands in terms of landforms, hydromorphology, water chemistry, nutrient availability, and the diversity of organisms and life forms they support. They are globally important for biodiversity, carbon sequestration, and the preservation of long-term paleoenvironmental records due to their slow accumulation of organic matter. In Croatia, the four southernmost peatlands (Sunđerac, Ljubica, Rakita, and Vodice kod Petrašice) are located along the Velebit Mountain range. However, for decades, scientific literature suggested the presence of an additional peatland known as “Sunđer.” This name caused confusion as it implied the existence of a separate site, distinct from Sunđerac. The misinterpretations probably stemmed from Pevalek’s 1925 report, where he misnamed Sunđerac, calling it “Sunđer”, and was inaccurate in his mapping of the location. The discovery of a permanent pond, Solila, close to the “Sunđer” locality, has reopened the debate and led to further ecological research. We investigated bryophytes, vascular plants and ground beetles, reliable indicators of peatland habitat quality, to test whetherSolila could represent the long-misidentified “Sunđer” mire. No species characteristic of peatland ecosystems were found in any of the indicator groups. The only vascular plant species associated with mire vegetation was Carex echinata , which also occurs in acidic grasslands and spruce mire forests. Nevertheless, in this relatively small area, we found a surprisingly high diversity of plants and ground beetles, including riparian species, that would not be found in this area without permanent surface water. Permanent ponds such as Solila can therefore make a significant contribution to localbiodiversity in karst landscapes.

Elodea canadensis Michx. (common waterweed) and Elodea nuttallii (Planch.) H. St. John (Nuttall’s waterweed), two invasive aquatic plants from North America, have coexisted in European water bodies since the early 20th century. New localities for both species in Croatia continued to be discovered during a study that ran from 2016 to 2023 as a part of the annual implementation of Water Framework Directive monitoring that covered the entire territory of Croatia (786 sampling points in total). Based on these data, the distribution and ecology of both species were analysed. Elodea canadensis was found at 30 sampling points, mostly in rivers, and E. nuttallii at 15 sampling points, mostly in artificial canals. Nearly three-quarters (72.5%) of all elodea sampling points were in the Pannonian Ecoregion. Elodea canadensis was discovered for the first time in the Continental—Dinaric and Mediterranean—Dinaric Subecoregions. To study the ecology of the species, for each sampling point, vegetation relevés were performed and monthly measurements of physico-chemical parameters were collected. The most common accompanying species for both elodeas are presented, and the difference in species assemblages between the sites with E. canadensis and E. nuttallii was confirmed with the ANOSIM test. Furthermore, Indicator Species Analysis revealed eight species characteristic of E. canadensis sites and eleven species characteristic of E. nuttallii sites. Fitting multivariate models (CCA and NPMR) to species abundance revealed the ecological reaction of E. canadensis and E. nuttallii to environmental descriptors. The most strongly contributing environmental descriptors that influence the distribution of both Elodea species are biochemical oxygen demand, electrical conductivity and total phosphorus. In Croatia, the replacement of E. canadensis with E. nuttallii was observed in several water bodies with high nutrient loads.

The liverwort flora of Bosnia and Herzegovina is still underexplored, and this especially applies to the annual ephemeral species that inhabit the drawdown zones of rivers, lakes and reservoirs. Field research in the Peripannonian part of Bosnia and Herzegovina resulted in new and noteworthy records of liverworts. Riccia cavernosa and R. rhenana were recorded for the first time in the liverwort flora of Bosnia and Herzegovina. R. glauca was confirmed for Bosnia and Herzegovina, while new localities were found for Ricciocarpos natans. Our results contribute to a better knowledge of the liverwort flora of Bosnia and Herzegovina, as well as the flora and vegetation of ephemeral wetlands.

This paper supplies new data on the occurrence of eight vascular plants (Carpesium abrotanoides, Guizotia abyssinica, Gypsophila fastigiata, Heliotropium supinum, Hermodactylus tuberosus, Polycarpon tetraphyllum, Pseudognaphalium luteoalbum, Reynoutria sachalinensis), three bryophytes (Corsinia coriandrina, Cryphaea heteromalla, Leptodon smithii), one lichen (Roccella phycopsis), one fungus (Mitrula paludosa) and one alga species (Trentepohlia aurea) in Croatia.

Floodplains are heterogeneous systems adjacent to large rivers periodically flooded by water originating from the river’s lateral flow. During floods, the water flows into the surrounding channels, ponds and lakes, creating an integrated dynamic system characterized by a mosaic of lotic and lentic habitats and by the exchange of nutrients and inhabiting organisms between the main river and its floodplain. This study included a total of 14 sampling sites in a floodplain of the Danube River, designated as a Ramsar site. Seven study sites were in near natural condition, while seven others were separated from the Danube floodplain by an embankment and thus were anthropogenically disturbed (e.g. by hydro–morphological alterations and pollution from agricultural fields). Odonata nymphs were sampled over a two–year period in each season using a benthos hand net. A total of 20 Odonata species were recorded. Some of the documented species are of national and/or international conservation concern, which confirms the conservation value of the habitats studied. Species richness, abundance, taxonomic and functional diversity of Odonata were significantly higher at the anthropogenically disturbed sites than at the near natural sites within the studied floodplain area and correlated positively with macrophyte assemblage metrics (species richness, abundance, diversity). The macrophyte assemblage metrics, water transparency, copper and nitrate concentrations and oxygen saturation in the water were key environmental factors shaping Odonata assemblages in the studied floodplain. As Odonata are used as bioindicators of freshwater status worldwide, the presented results could be used in the protection of endangered wetland ecosystems and their biota. The importance of aquatic macrophytes for the conservation of the local Odonata diversity should be considered in the management of anthropogenically disturbed habitats in protected areas.

The area of “Zelinska glava”, under the protection of the Public Institution “Green Ring of Zagreb County (Zeleni prsten Zagrebačke županije)”, covers an area of 9.5 km². Research into the area’s vascular flora was conducted during the growing seasons of 2019 and 2020. A total of 330 taxa of vascular flora were recorded, classified within 82 plant families. Fourteen species of bryophytes were added to the list of vascular flora. The most common families are Compositae (13%), Fabaceae (7%), Rosaceae (7%) and Lamiaceae (6%). The analysis according to habitats shows that the most species inhabit forest edges along paths (51%), followed by meadows (18%). Phytogeographic analysis shows that the Eurasian floristic element dominates (45%), followed by cultivated and adventive plants (10%). Regarding life forms, the largest number of taxa belong to hemicryptophytes (51%). According to the Red Book of Croatian Vascular Flora, 12 taxa belong to one of the threat categories. Eight taxa are strictly protected by law, seven of them belonging to the Orchidaceae family. A total of eight invasive species were recorded in the study area.

It has been widely documented that the complex structure of forest ecosystems supports considerable bryophyte species and functional diversity. In this study, we assessed the diversity, distribution and ecological and phytogeographical features of bryophytes across a gradient of temperate forest types on Mt. Papuk. This is the largest and highest mountain in the lowland, Pannonian part of Croatia, with high geological diversity and various temperate forests covering 95% of the mountain. According to the predominant tree species (oak vs. beech), geological bedrock (calcareous vs. siliceous) and soil reaction (alkaline vs. acidic), 21 study plots were classified into four distinct forest types. In all, 184 bryophyte species (35 liverworts and 149 mosses) were recorded. Although the forest types investigated did not differ significantly with respect to species richness, each was characterized by a considerable number of diagnostic bryophyte species. According to our results, one of the main ecological factors determining the variability of the forest bryophyte composition was geological bedrock and the associated soil reaction. Basiphilous forests developed on carbonate bedrock harbored more thermophilous and nitrophilous bryophytes and were characterized by southern-temperate and Mediterranean–Atlantic biogeographic elements. In contrast, acidophilous forests growing on silicate bedrock were characterized by wide-boreal and boreo-arctic–montane elements, i.e., bryophytes indicating cooler habitats and nitrogen-deficient soils. Based on the results, we hypothesized that the main latitudinal biogeographic distinction between southern and northern biogeographic elements is driven more by geological substrate than by the main tree species in forest communities. The present study confirmed previous findings that bryophytes are good and specific habitat indicators and show associations with different forest types, which can help to understand the complexity, ecological microconditions and biogeographic characteristics of forest communities.

Bryophyte flora of the Significant Landscape Lower ”Kamenjak and Medulin Archipelago” in Istria (western Croatia) was studied from 2019 to 2021. The study resulted in a list of 14 liverwort and 60 moss taxa. Tortula pallida, Bryum gemmilucens, Microbryum davallianum var. conicum and Microbryum muticum are new national records. The prevalence of Mediterranean-Atlantic, temperate and southern-temperate chorotypes corresponds well with the biogeographical characteristics of the studied area. The turf life-form and colonist life strategy, predominantly represented by small Pottiaceae species, prevailed within the study. They mostly inhabited periodically moist soil of open habitats in olive groves, maquis and garrigues. This study aimed to address the significant lack of current data on bryophytes in coastal parts of Croatia.

In terms of plant biodiversity, the Plitvice Lakes are one of the most valuable areas in Croatia. This natural barrage lake system of 16 larger and several smaller lakes, separated with tufa barriers in form of numerous waterfalls of different size, height and water velocity, stretches along 8 km, representing the largest habitat of the tufa forming moos communities (Cratoneurion commutati) in Croatia. Indeed, the Plitvice Lakes are the largest area in Europe supporting the development of these communities. Furthermore, the Lakes are valuable as the largest habitat of stonewort communities (Charetea intermediae) in Croatia. On the other hand, karst terrain is not favourable for the development of marshland vegetation (Phragmito-Magnocaricetea), and therefore this vegetation type covers only small areas, being mostly confined to lake margins. The recent spread of marshland vegetation could indicate the eutrophication of the lake system.

Popis flore mahovina Hrvatske dopunjen je sa sedam novih vrsta te jednim varijetetom na temelju četiri znanstvene publikacije koje su objavljene tijekom posljednje godine. Herzogiella striatella (Brid.) Z. Iwats. zabilježena je u Gorskom kotaru, Bryum barnesii J.B. Wood ex Schimp. na rijeci Zrmanji, dok su Bryum gemmilucens R. Wilczek & Demaret, Tortula pallida (Lindb.) R. H. Zander, Microbryum muticum (Venturi) Cl. Schneid., Th. Schneid. & Mahevas i M. davallianum var. conicum (Schleich. ex Schwägr.) R. H. Zander zabilježeni tijekom istraživanja provedenog na rtu Kamenjak u Istri. Nadalje, Hylocomiastrum umbratum (Hedw.) M.Fleisch. i Timmiella barbuloides (Brid.) Mönk. pronađene su u procesu sistematizacije, revizije i geokodiranja povijesne kolekcije mahovina iz zbirke ZA.

Mannia triandra (Scop.) Grolle is a rare thalloid liverwort species, known from a few, mostly sporadic, historical records in Croatia. In the recent years, two findings have been recorded on Mt Žumberačka Gora and one from Plitvice Lakes, and subsequently published. During 2022, two adjacent populations close to these previously known localities were found, but also a first locality in Gorski Kotar region (in the canyon of the River Kamačnik) was recorded. In addition, an old literature record from the area of Dubrovnik city from the beginning of the 20th century was found while browsing literature for this paper. Thanks to these new findings, we are now closer to a better understanding of the species ecology and habitat preferences in Croatia.

During growing seasons 2018-2019 and in winter 2021, the flora of vascular plants and bryophytes of the Nature Monument Vrelo Une in southern Croatia was studied. The previous floristic data available for this area, covering 9.58 ha, are sparse, and this study recorded 219 taxa of vascular plants from 59 families. The species-richest families are Compositae (10.5%), Fabaceae (8.2%), Poaceae (7.8%), and Lamiaceae (6.4%). Additionally, 64 bryophyte species (14 liverworts and 50 mosses) were recorded. The spectrum of biogeographic elements of vascular plants places the study area in the Euro-Siberian region, at the meeting point of two vegetation sub-zones within the European broadleaf deciduous forests zone – thermophilic, sub-Mediterranean forests of the class Quercetea pubescentis and mesic forests of the class Carpino-Fagetea sylvaticae. The species of the South-eastern European and Illyrian elements give a local distinctiveness to the flora. The biogeographic elements of bryophytes are less sensitive but reflect the same biogeographical pattern. Since most of the researched area is covered by forests and thickets, the largest number of species of vascular plants are associated with these particular habitats, while rocks and aquatic habitats are the most important for bryophyte diversity. In terms of the IUCN categories, four species are classified as near threatened, three as least concern and three as data deficient. Invasive species have not been recorded.