Fig 2 - uploaded by Zigmantas Gudžinskas
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Assessment of Elatine hydropiper coverage in the sampling plot. (A) Patches of Elatine hydropiper with outlines. (B) Arrangement of Elatine hydropiper patches in the sampling plot.
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Background:
Wet, intermittently flooded freshwater coastal and shallow water habitats are notable for their high biodiversity. Many of the usually semiaquatic annuals or small perennials common in such habitats are in decline due to the high sensitivity of such habitats to changes caused by anthropogenic and natural factors. The Euro-Siberian semi...
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Context 1
... number of patches of Elatine hydropiper and the area covered by the patches (with precision of 0.01 cm 2 ) in the sampling plot were calculated using Digimizer software 5.7.2 (MedCalc Software Ltd, Ostend, Belgium). In the uploaded image with the field frame used for scaling, all distinct outlines of Elatine hydropiper patches were delineated (Fig. 2). Other plant species and other objects within the sampling plot were ...
Citations
... Approximately 90% of the historically known localities of A. vesiculosa worldwide were estimated to have become extinct within a century and a half [15]. The main causes of the extinction of many A. vesiculosa populations include direct anthropogenic impacts (habitat destruction, drainage, intensive agriculture, eutrophication, municipal pollution, etc.), as well as natural habitat succession, mainly associated with habitat degradation and climate change [14,48,50,91]. ...
The European Habitats Directive was adopted to halt the rapid loss of biodiversity and has become an important instrument for protecting biodiversity in the European Union. Three aquatic plant species protected under the European Habitats Directive have so far been found in Lithuania: Aldrovanda vesiculosa, Caldesia parnassifolia, and Najas flexilis. Our aim in this study was to evaluate the former and current distribution and the status of conservation of the target species. Screening for the above-mentioned protected aquatic plant species was performed in 73 natural lakes throughout Lithuania in 2019-2021. We confirmed extant populations of Aldrovanda vesiculosa in four lakes, Caldesia parnassifolia in two lakes, and Najas flexilis in four lakes in the northeastern part of the country. We studied Aldrovanda vesiculosa populations three times (2015, 2019, and 2022) in Lake Rūžas and once each in Lake Apvardai and Lake Dysnai (2020). The population density of Aldrovanda vesiculosa ranged from 193.4 ± 159.7 to 224.0 ± 211.0 individuals/m 2 , the mean length of plants ranged from 12.5 ± 2.1 to 14.3 ± 2.7 cm, and the mean number of apices ranged from 2.0 ± 0.7 to 2.2 ± 0.9 per individual. The habitat of Aldrovanda vesiculosa in Lake Rūžas covered an area of about 3 ha. The number of generative individuals of Caldesia parnassifolia widely varied between years in Lake Rūžas. All populations of Najas flexilis were small, although the potential habitats in the studied lakes cover relatively large areas. We propose designating all lakes with populations of Aldrovanda vesiculosa, Caldesia parnassifolia, and Najas flexilis as special areas of conservation, as well as developing and implementing action plans for the conservation of these species and their habitats.
... Moreover, seeds may be affected by animals and microorganisms, which can influence their viability and survival in soil [23]. The proportions of damaged, intact, non-viable and viable seeds in soil seed banks show the relationship between seed input into the soil seed bank and its depletion [24,25]. On the other hand, the proportion of damaged, non-viable and viable seeds also gives some indication of the type of seed bank [26]. ...
Soil seed banks of alien plant species are sources of propagules that play a crucial role in plant population dynamics. Studies on seed banks of woody alien species are crucial for understanding mechanisms of their encroachment on natural habitats. This study aimed to compare vertical distribution, density and composition of seed banks formed by native Cornus sanguinea subsp. sanguinea and alien C. alba, C. sericea and C. sanguinea subsp. australis in the Southern Hemiboreal zone of Europe. Five sites for each of four taxa were selected for the study, and seeds were sampled using the soil core method (400 samples in two soil layers: the upper, 0–5 cm, and the lower, 5–10 cm). Extracted seeds were tested with tetrazolium chloride stain to assess their viability. Differences in the seed banks among taxa were compared using generalised linear mixed models (GLMM). The GLMM analysis revealed significant differences in soil seed bank densities in the upper soil between the studied taxa (p < 0.001). We found that two of the alien taxa (C. alba and C. sanguinea subsp. australis) formed a much denser seed bank containing more viable seeds than the native Cornus sanguinea subsp. sanguinea. All three alien species contained more viable seeds (from 40.7% to 45.2% in the upper soil layer) than the native C. sanguinea subsp. sanguinea (19.4% in the upper and 18.2% in the lower soil layer). The cover of Cornus and habitat type had no significant effect on the density of the seed bank, according to GLMM. This study supports the hypothesis that seed banks of alien C. alba and C. sanguinea subsp. australis are denser than those of native C. sanguinea subsp. sanguinea. Furthermore, the seed bank of alien taxa contained more viable seeds than the seed bank of C. sanguinea subsp. sanguinea. Results of this study contribute to the understanding of the invasiveness of alien Cornus taxa.
Many native plant species colonise anthropogenic habitats, but relatively little information is available on the status and development of their populations under unusual conditions. The most reliable information on the status and performance of plants in particular habitats is obtained through population studies. The study aimed to determine the characteristics of Equisetum variegatum populations occurring in natural and anthropoge-nic habitats. Nine coenopopulations of Equisetum variegatum occurring in natural and anthropogenic habitats were studied in four administrative districts (Kelmė, Lazdijai, Trakai and Varėna) of Lithuania. The ramet density, shoot height, total number of shoots and the number of fertile and sterile shoots and buds in a ramet were assessed. The density of Equisetum variegatum ramets was significantly higher in natural habitats than in anthropogenic habitats. The largest mean height of shoots was found in shrubland and shallow water habitats, whereas the largest mean number of all shoots, fertile shoots and buds in a ramet was recorded in dry sands. Old shoots in natural habitats comprised a significantly smaller portion (18.1%) of all shoots than in anthropogenic habitats (42.8%). Thus, all the studied traits can be used to evaluate the status of the populations. Long-term studies of Equisetum variegatum populations should be performed to determine how they change in response to the succession of natural and anthropogenic habitats. As the natural habitats of Equisetum variegatum decline, anthropogenic habitats may be considered the refugia for their populations.
Shallow lake restoration typically focusses on the re‐establishment of macrophytes. The likelihood of a species returning to a site is contingent on dispersal, proximity to propagule sources, and the on‐site propagule‐bank viability. We explore the potential of palaeoecological records in combination with botanical surveys and distribution maps, to ascertain the loss of three submerged macrophytes ( Littorella uniflora , Najas flexilis , and Elatine hydropiper ) from, respectively, two lakes (Barton Broad, Norfolk and Esthwaite Water, Cumbria) and one lake landscape (Greater Glasgow, Scotland). We discuss re‐establishment likelihood when accounting for species' autoecology and current water‐chemistry conditions. L. uniflora is widespread in the United Kingdom but absent locally in Norfolk without known seed bank, hence is unlikely to naturally recolonise Barton Broad. Furthermore, current conditions are unsuitable for this species suggesting that nutrient reduction is required prior to translocation. N. flexilis is extinct in Cumbria and the long distances involved (>100 km) for recolonisation of Esthwaite Water suggest that spatial dispersal is unlikely, rendering the seed bank the last chance of natural recovery. Alternatively, translocation may be feasible. E. hydropiper is a nationally scarce species in the United Kingdom yet would have only a short dispersal distance (~10 km) to recolonise Loch Libo, hence there being no requirement for translocation. In exploring the recovery possibilities for the three focal plant species, we develop a time–space integrated framework that can be employed to guide conservation decisions for other species, enabling a more rational use of translocations in the future, in line with international guidelines.
Neotinea ustulata (Orchidaceae) is a rapidly declining species throughout much of its range and is classified as critically endangered in Lithuania. Most of the historical occurrences of the species were concentrated in northwestern Lithuania, while the largest extant population was in the southern part of the country. In July 2022, a new population of Neotinea ustulata was discovered in an urbanised habitat in Šiauliai in northern Lithuania. A total of 84 individuals of this species were recorded in the population. In the southern part of Lithuania (Varėna distr.), the studied population comprised 86 individuals in 2002 and had decreased to 64 individuals by 2022. The total currently known population of the species in the country consists of about 150 individuals and remains critically endangered. The individuals of Neotinea ustulata studied in Šiauliai were significantly lower and had shorter inflorescences than the plants studied in Varėna district in 2002 and 2022. Since the population of Neotinea ustulata in Šiauliai is in an urbanised area, its conservation poses a significant challenge, making it difficult to make long-term predictions on the development of the population. Therefore, it is essential to continue searching for populations of Neotinea ustulata in the country, perform detailed studies on the plants' reproductive potential, and properly organise the management and protection of extant populations and their habitats.
Laphangium luteoalbum (Asteraceae) is a widely distributed species native to Eurasia; however, it is rare or endangered in some regions of Europe and included into the lists of protected species. In Lithuania, Laphangium luteoalbum was recorded in the southern part of the country, mainly along the banks of the Nemunas River in the 20th century. In contrast, it was found only in the 19th century in the western part of the country. During the research in Curonian Spit National Park (Neringa, western Lithuania), a relatively large species population was found in the transition zone between the dune grassland and wet dune slack habitats. The total population in 2020 consisted of about 500 individuals distributed over an area of about 310 m 2. We assume that the seeds of this wind-dispersed plant may have been transferred from other regions of Europe by the wind. However, it cannot be excluded that the plants found are descendants of populations previously recorded in the country. The species is most threatened by the loss of wet, open sandy habitats due to eutrophication of water bodies and subsequent changes in bank vegetation. Laphangium luteoalbum was classified as data deficient (DD) in the last assessment according to the IUCN criteria. Still, a reassessment based on the current data indicates that the species should be considered critically endangered (CR) in Lithuania.
