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The participation of species of alien origin in the flora of individual regions of the world is increasing. A large proportion of these species pose a threat to biodiversity. Issues of the dynamics of changes in the flora and the scale and pace of the processes, with particular emphasis on the biology, ecology, chorology, and genetic variability of the populations of plants of alien origin, including those alien species which are invasive, have been the subject of many years of research in this field in Poland. The present study is an overview of the state of research on invasive plant species in Poland, including the main results of the basic and applied research which have provided the basis for (i) the preparation of a list of invasive plant species for Poland; (ii) assessing the degree of invasiveness of the species analysed, in accordance with the adoption of criteria and the development of methodological solutions. In this work, a new version of the list of invasive plant species has been prepared on the basis of earlier studies, combining theoretical and practical aspects of definition, and it is compared with the list of invasive alien plant species considered to constitute a threat to the EU and Poland as a member country. The categorization (risk assessment) of invasive alien species along with the identification of the most endangered types of natural habitats is often used in practice in the management of invasive plants in Poland. The results of our research have fed into the formulation of legal regulations at the global and regional levels.

The forest environment is considered to be more resistant to penetration by alien plant species than other terrestrial environments, which generally are significantly modified by humans. A major environmental threat to vegetation is posed by alien species that are capable of spontaneous expansion in natural or semi-natural communities, and above all in forests. This paper presents a naturalization scale of alien vascular plants in forests of Poland, based on knowledge of species classified as naturalized elements of the Polish flora. Using the research results and observations of other authors, as well as literature data, a list of 180 taxa of such plants was compiled. The classification uses the following categories: life form, systematic affiliation, and origin or status in the Polish flora. The analysis revealed that not all of the considered alien species showed an ability to penetrate forest communities and that only a few of them have developed stable populations in the best-preserved natural and semi-natural phytocoenoses. About 20% of the anthropophytes found in forest communities strongly affect the composition and structure of the forest phytocoenoses.

In climbing plants, fruits can be formed at different heights, depending on the height of external support. However, the effect of height on fruit and seed traits in invasive vines of Cucurbitaceae has not been intensively studied so far. In Europe, Echinocystis lobata, a North American member of Cucurbitaceae, is considered one of the most abundant invasive alien plants spreading in natural riparian forests, thickets, and tall herbs, whereas it is a rare species in urban woodlands. In this study, we tested the variability of selected fruit and seed traits of E. lobata in connection with habitat origin (natural, semi-natural, and anthropogenic), habitat type (using the EUNIS habitat classification), height (the distance between the fruit and the ground), and geographical position. The study was conducted in 2018 in 65 sites located in Latvia, Lithuania, Poland, and Slovakia. In each study site, a random sample of 10 fresh mature fruits of E. lobata was collected from subsequent 0.50 m intervals of height. The length, the width, and the weight of the fresh fruits, as well as the total number of seeds and number of undeveloped seeds per fruit, were examined. Moreover, the well-developed seeds from selected study sites were weighed. The statistical analysis showed the significant effect of habitat origin, habitat type, and height on most of the studied fruit and seed traits. The largest range of height (from 0.00 to 4.00 m) was observed in two types of habitats (F—heathland, scrub, and tundra; and G—woodland, forest, and other wooded land). The total number of seeds per fruit was positively correlated with the length, width, and weight of the fresh fruits. The fruits were a little heavier and bigger in natural habitats located in the northeast of the study area. The distribution of fruits at different heights may contribute to better dispersal of seeds by animals and wind, and may also better protect the seeds from being eaten by granivorous animals. The defence against seed-eating animals is expected to be stronger in semi-natural habitats, as well as on banks and shores of inland surface waters, where the seed production is the highest. The influence of seed traits on seed germination and seedling survival in various habitats and their importance in the invasiveness of E. lobata require further study.

The phytotoxic potential of Veronica peregrina L. was assessed by determining its influence on the germination and growth of the test plant Sinapis alba L. and identification of the allelochemicals...

The cosmopolitan water caltrop plant (Trapa natans L.) produces nuts, which in the maturing process develop very hard pericarps. This hardness, together with structure and shape (external spikes) of pericarp and seed, and the water contained in the fruit are responsible for their mechanical properties. This study determined the force needed to break Trapa natans nuts at various drying stages, with tests having been carried out at weekly intervals until the fruit dried completely. The amount of force necessary for cracking nuts at each of the 6 drying stages was determined, as well as the work of crushing calculated until the greatest compressive force (crushing force) was reached. The force needed to rupture the hydrated fruit in the horizontal plane was higher than that necessary for the rupture of dried fruit. The experiment showed that the maximum force needed to crush the fruit was 828.7 N and occurred when crushing the fruit after 2 weeks of drying, while the largest calculated crushing work was 2185.5 mJ for the same fruit. Other strength parameters were introduced to characterize mechanical properties of water caltrop in a more extensive scope. These are hardness defined as a ratio of compressive force increment to strain increment, specific crushing energy defined as a ratio of crushing work to water caltrop’s mass, and unit crashing force defined as a ratio of crushing force to caltrop’s thickness. All these parameters reached their highest mean values for pericarps after 2 weeks of desiccation. Mass measurements were also applied in modelling the desiccation process by the exponential function. The very dense pericarp material, after reaching maturity, slightly changes during drying. It can be used industrially as an extremely durable and biodegradable biological material. Results also suggest that the great evolutionary success of the species may result from the ability of the pericarp to protect its seeds, leading to the spread of this species in aquatic environments.

Coleanthus subtilis is a rare ephemeral plant species that grows on exposed river banks or pond bottoms. Its natural European localities are considered to be historical ones; however, new localities in man-made habitats have been increasingly reported. Although C. subtilis is protected under international agreements, little is known about the influence of soil chemistry on this species, thus we ask the following questions: i) what is the range of basic soil chemistry parameters for sites colonised by C. subtilis in Poland; ii) how does the soil chemistry influence population density and biomass production of the species; and iii) what is the influence of the soil chemistry on the species composition of plant communities with C. subtilis . We analysed the chemistry of the bottom sediments (pH and concentrations of N, P, K, Ca, Mg, Na, Mn, Fe, Cd, Co, Cr, Cu, Ni and Pb) of 11 fishponds; population density and biomass production were analysed on 47 plots, from which the species composition was determined on 24 samples. The chemistry of the bottom sediments significantly influenced the population density and biomass production of C. subtilis . It was restricted to acidic and neutral substrates and preferred soils rich in N, K, Ca, Mg and Na but poor in P. In such habitats higher biomass production was obtained by C. subtilis , but none of the factors significantly influenced the species composition in its communities.

Carex buekii is a tall sedge, forming large stands in wetlands, particularly in river floodplains across Central Europe and thus on many sites determining the typical appearance of riverine habitats. Our paper aims at increasing the knowledge on ecology of C. buekii and its role in the wetlands. Field data were collected in Poland, the Czech Republic, Slovakia, Hungary, and Italy. Carex buekii usually occurs in nutrient rich habitats, but is also capable of colonising relatively nutrient-poor ones; it grows on both acidic and alkaline soils (pH 3.3–7.4) with diverse concentrations of assimilable elements (Ca, Mg, P, K). One of the most important ecological characteristics of C. buekii is its relationship to the floodplains of watercourses. It seems to be dependent on, or at least very tolerant to regular disturbances by streaming, floods and transport of sediments. Carex buekii usually forms relatively uniform stands of its own association, Caricetum buekii. The species most frequently accompanying C. buekii are Urtica dioica, Calystegia sepium, Galium aparine, Rubus caesius, Phalaris arundinacea, and Cirsium arvense. The sedge also occurs in the understorey of forests with e.g. Alnus glutinosa, Salix fragilis, Padus avium, and Quercus robur. Carex buekii is able to colonise man-made or man-changed habitats such as railway embankments and roadsides or regulated river banks. Taking into account the IUCN Red List Criteria we propose to regard C. buekii as a least-concern (LC).

Field margins are inherent elements of European agricultural landscapes, thought to be crucial for maintaining a high biodiversity level. The interactions between the structure of field margins and biota have been recognized, yet the understanding of the importance of various components of the margins and adjacent areas is still incomplete. The aim of our study was therefore to determine the relative importance of structural features of the margins and diversity of adjacent crops for birds breeding in field margins. The study was carried out in 70 field margins covered with semi-natural vegetation, situated in SW Poland. Both the number of species and bird density were most strongly positively related to the development of tree and shrub layers, while presence of ditches and percentage of reed cover (positive effects) had much less importance. Analyses conducted at the species level revealed the complexity of bird-habitat interactions resulting from various requirements of individual species. Overall, for 22 abundant species and for the threatened species, the development of the shrub layer turned out to be a particularly important feature of field margins positively associated with occurrence of e.g. Emberiza citrinella, Linaria cannabina and Streptopelia turtur. Other significant positive effects had the development of the tree layer (e.g. Turdus merula and Turdus philomelos), presence of ditch (e.g. Acrocephalus palustris, Sylvia communis), and number of gaps in woody vegetation (e.g. Lanius collurio). The diversity of adjacent crops had positive effects only to some threatened species (e.g. L. collurio and E. calandra). Abundances of common and threatened birds were not correlated, which reflects different habitat demands of these two groups. Because of diverse bird-habitat relationships, maintaining a variety of field margins (in particular the shrubby ones), should be accepted as a rule in biodiversity-oriented management of agricultural landscapes.

A study was conducted to determine the occurrence of bird species in relation to 70 field margins of an agricultural landscape in SW Poland. Three types of margins were divided according to the volume of tall vegetation, i.e. herbaceous, shrubby, and tree lined. Fifty breeding bird species were recorded, with a mean density of 33.2 pairs/km. The dominant species were non-threatened and were characteristic of forests or of the field-forest mosaic. Tree lined margins showed the highest abundance and bird species richness. Shrubby margins supported the second highest, while open habitats ranked last. Abundances in ecological guilds were affected by the margin type, the presence of field roads, and especially the presence of ditches in the margin structure. Redundancy Analysis showed clear differences in bird communities between the discernable types of field margins. Species richness increased in the combinations of various margin types. In heterogeneous farmland environmental policy should aim at maintaining various types of field margins at high density in the agricultural landscape.

Carex buekii is a rare species, native to Europe and the Middle East, although its full geographical distribution is poorly known. Attention is paid to the global occurrence of C. buekii. Its situation and threat status is presented in relation to each country from which this species is known. Carex buekii forms four (rare) hybrids, each with other members within the section Phacocystis. Special attention is paid to the comparison of Carex buekii with the recently described Central European C. randalpina; the taxonomic problems of those two species are briefly discussed.

Lindernia procumbens in Poland: the relationship between weather conditions and the occurrence of the species New data regarding the occurrence of Lindernia procumbens (prostrate false pimpernel) are discussed and its current geographical range in Poland is given. A comparison of its past and present distribution in Poland indicates an advancement of the distribution limit northwards, which may be caused by climate changes, mostly, by an increased number of heat waves in the warm half-year. The relationship between the occurrence of the species and specific meteorological conditions, especially, unusually hot and dry summer periods, is analysed using long-term meteorological surveys.

The present study is focused on Potamogeton polygonifolius – the species considered to be endangered in Germany, the Czech Republic, Poland and Switzerland. Field studies were carried out in Lower Silesia and Lusatia in southwestern Poland in order to verify the present state of the marginal populations of P. polygonifolius, to determine the habitat preferences of the species in the study area, to compare the ecological data between marginal and central populations and finally to recognise the factors constraining the easternmost limit of the P. polygonifolius. In total, 18 populations were examined, and 11 releves were collected. The releves gathered were compared with 95 releves made in northwestern Germany, and with 10 releves collected in the German part of Lusatia. There were no significant differences between the ecology of populations of P. polygonifolius on the eastern edge of its range and those in the central part. P. polygonifolius was found growing both in natural habitats like unspoiled peat bogs, and in anthropogenic habitats such as exploited peat bogs and drainage ditches. In both types of habitats its populations were abundant and competent in terms of generative propagation. The lack of geographical barriers as well as biology and fitness of P. polygonifolius individuals from the study area suggest that marginal populations are possibly a part of a large metapopulation, covering the whole (Polish and German) area of Lusatia, however, this hypothesis was not tested in detail. The main factor shaping the easternmost limit of the general range of P. polygonifolius is most likely climate, which prevents P. polygonifolius from spreading farther eastwards.

Using the assessments of conservation status of flora and fauna, we discuss declining species in semi-natural field margins and stress the importance of these vanishing habitats. Seventy field margins in the diverse farmland of SW Poland were investigated with regard to their vascular plants, bryophytes and breeding birds. We checked the occurrence of threatened and conservation concern species, i.e. those listed in local, national or European threatened species lists, and birds with an unfavorable conservation status in Europe. Of a total of 673 species, 18 classified as threatened were recorded: 12 vascular plants (2.2 % of the total number of species), five bryophytes (5.6 %), and one bird species (2.0 %). Threatened plants occurred in 18.6 % of study plots, bryophytes in 20.0 % and birds in 12.9 %. Eleven bird species, noted in 95.7 % of study plots, had an unfavorable conservation status in Europe. Increasing volumes of trees and shrubs significantly increased the overall richness in each taxa. In percentage terms the occurrence of focal species in all three taxa tended to be higher in shrubby than in herbaceous and tree-lined margins. Our data demonstrate that field margins in Central European arable farmland regularly support rare and threatened species, and therefore deserve greater conservation efforts. Red lists along with alternative listing approaches can be employed to evaluate the biodiversity of fine-scale habitats, but their applicability depends on the taxonomic group and geographical scale of the lists, reflecting different conservation priorities.

Until recently Arum maculatum was considered the only representative of genus Arum in our country. The record of Arum ulpinum Schott and Kotschy in localities in south-east Poland, from which Arum muculatum L. had been reported previously, encouraged us to undertake the study on the distribution of both species in the west of Poland. We found that Arum alpinum occurs also in Silesia, whereas the range of Arum muculatum is restricted to northwestern part of Poland. So far a total of 17 localities of Arum maculatum were recorded in Poland (within the present borders). Only 7 of them exist at present, 4 in natural and 3 in synanthropic sites. In view of such a small number of existing localities, the species should be regarded as endangered in Poland. In this paper we present the diagnostic features of both species and their distribution on ATPOL base-maps.

The paper presents results of geobotanical and taxonomic studies on the distribution and habitat requirements of Nymphaea candida in southern Poland. The researches were conducted in southern Poland in 2003-2009, in the provinces of Lower Silesia, Lublin, Małopolska, Opole, Silesian province as well as, in southern parts of Mazowieckie and Lubuskie. Flowers, leaves and fruits of Nymphaea species were collected from 27 locations. Altogether pollens from 73 populations of N. candida and 18 of N. alba from all the researched area were measured. The trophic level of an ecosystem was evaluated according to the results of the total nitrogen, total phosphorus, chlorophyll a, transparency and biological parameters. As the result of the studies of more than 200 water bodies, 57 localities of N. candida were documented within the investigation area. The populations of N. candida occupy mid-forest water bodies and river ox-bow lakes. A significant number of populations was also found in artificial reservoirs - fish ponds. The most suitable habitat conditions for N. candida occur in shallow waters in the shore zone with the amplitude of the water column vary from 0.5 to 2 m. Regarding the trophy level, N. candida occupies different habitats, mainly mesotrophic and also eutrophic with high content of organic matters. Considering the 15 checked morphological parameters, especially the stigma diameter, the number of carpellary teeth, flower and pollen diameters, the found and collected specimens of N. candida significantly differ from N. alba. The study confirms that N. candida ocurrs in whole lowland Poland without any regional distribution gaps. According to the IUCN guidelines to species assessment the data gathered during the presented study do not allow to classify N. candida as a vulnerable species in Poland. Still existing populations for more than 150 years, numerous stable locations, abundant populations, a habitat accessibility, a biotope extent, an ecological amplitude against the trophy level and direct human impacts suggest, that the species should be regarded as a least concern (LC) taxon.