STUDY CONCERNING ALIEN FLORA FROM DÂMBOVIȚA COUNTY (ROMANIA)

In the past two decades, ecologists have focused mainly on two basic aspects of biological invasions: firstly, the particular characteristics of species that determine their invasiveness, and secondly, on the properties of communities that determine their resistance to invasion. Depending on the period when it was unaccidental or accidental introduction of alien plant species, they are divided into four categories: archaeophytes, paleophytes, neophytes and neotophytes. In relation to the status after the introduction and the level of sustainability, alien plant species are grouped into: ephemeral, naturalized and invasive. In relation to the total invasive alien weed flora of the Republic of Serbia attribute most aggressive, in terms of crop production, can be assigned to species: Abutilon theophrasti Medic., Amaranthus retroflexus L., Ambrosia atremisiifolia L., Cuscuta campestris Yunk., Erigeron canadensis L., Galinsoga parviflora Cav., Iva xanthifolia Nutt., Polygonum aviculare L., Portulaca oleraceae L., Sorghum halepense (L.) Pers., Stenactis annua (L.) Ness. and Xanthium strumarium L. On the other hand, in the category of invasive alien weed species, which for now does not occur in a high abundance in the crop field, but that can be expected in the near future in the crop field if we do not take control measures, that’s are: Amaranthus deflexus L., Asclepias syriaca L., Ambrosia trifida L., Eleusine indica L., Solidago canadensis L., Kochia scoparia (L.) Schrad., Iva xanthifolia Nutt., Fallopia japonica Houtt., Xanthium spinosum L., etc.

In Western Pomerania, as in other areas of Europe, alien species play an increasingly important role. In particular, invasive plants tend to spread rapidly and in large numbers which may reduce diversity of native species, leading to the phenomenon of “trivialisation of flora”, and transform ecosystems. The list of invasive species (32 taxa) includes alien species occurring throughout Western Pomerania, and penetrating natural or semi-natural habitats. The second group consists of potentially invasive species (23 taxa), i.e. those distributed across the area under study and tending to increase the number of their localities in semi-natural and natural habitats, taxa invasive only locally, as well as species with missing data, which does not currently allow including them into the first group. Invasive weeds, as well as some epecophytes and archaeophytes occurring only on anthropogenic sites and tending to spread, were not taken into account. Among hemiagriophytes, the most common and troublesome ones are: Conyza canadensis, Erigeron annuus, Lolium multiflorum, Lupinus polyphyllus, Solidago canadensis, S. gigantea. Among holoagriophytes, i.e. the taxa which received the highest naturalisation status, very expansive species, successful in land colonisation, like Acer negundo, Bidens frondosa, B. connata, Clematis vitalba, Elodea canadensis, Epilobium ciliatum, Heracleum sosnowskyi, Impatiens glandulifera, I. parviflora, Padus serotina, Quercus rubra and Robinia pseudoacacia, should be given particular attention. Among the invasive and potentially invasive species, most taxa penetrate plant communities of the Artemisietea and Molinio-Arrhenatheretea class, followed by Querco-Fagetea, Vaccinio-Piceetea, Stellarietea mediae, Salicetea purpurae and Koelerio-Corynophoretea. The number of invasive species is twice as high when compared to the situation of these species in Poland; on the contrary, the number of species inhabiting anthropogenic, semi-natural and natural habitats is two times lower, while that of holoagriophytes and hemiagriophytes is 56.3% and 43.7%, respectively. It seems that in the case of some invasive and potentially invasive species, a decrease in the number of their locations may be observed from the west to the east (e.g. for Acer negundo, Bromus carinatus, Clematis vitalba, Helianthus tuberosus, Lycium barbarum, Reynoutria japonica, Rosa rugosa, Vicia grandiflora). Distribution patterns for some species (e.g. for Parthenocytisus inserta or Xanthium albinum) are indicative of a likely major role of the Odra River valley in the spreading of invasive species. It should be kept in mind that the area of the North-West Poland is poorly examined in terms of its flora, so the results provided in this paper are tentative. Nevertheless, the maps illustrate colonisation trends and directions and, moreover, have been so far the only attempt to synthesise this problem in NW Poland.

Based on the review of long-term studies (2008-2015) of weed flora in various organic crops in Vojvodina (cabbage, lettuce, soybean, onion, carrots, maize, marigold, dill, buckwheat, potato, basil, lucerne), a total of 88 plant species were found, 53 (60%) of which are alien (non-native). By analyzing the invasiveness status of alien taxa according to different categorizations, we highlight the presence of 14 invasive alien species (9 neophytes; 5 archeophytes). The presence of 4 taxa, considered invasive according to all of the categorizations analyzed, stands out: Ambrosia artemisiifolia, Conyza canadensis, Erigeron annuus and Galinsoga parviflora.However, according to the databases of invasive plants in the territory of Serbia, 6 more species, are considered invasive, namely: Amaranthus retroflexus, Datura stramonium, Echinochloa crus-galli, Portulaca oleracea, Sorghum halepense and Veronica persica, of which only E. crus-galli is categorized as highly invasive. Of all the taxa that are considered highly invasive in Serbia, only A. artemisiifolia (58%) and E. crus-galli (33%) are present in organic crops with a higher frequency of occurrence, meaning that the organic crops in Vojvodina currently do not represent the main refuge for these species. However, due to their exceptional ability to rapidly spread and occupy new spaces, continuous research of invasive plants is needed, not only of those which are categorized as such in Serbia, but also of those which are considered as invasive in the wider European region.

Invasive plant species (IAS), with their numerous negative ecological, health, and economic impacts, represent one of the greatest conservation challenges in the world. Reducing the negative impacts and potentially exploiting the biomass of these plant species can significantly contribute to sustainable management, protect biodiversity, and create a healthy environment. Therefore, the main objective of this study was to evaluate the nutritional potential, phytochemical status, and antioxidant capacity of nine alien invasive plant species: Abutilon theophrasti, Amaranthus retroflexus, Ambrosia artemisiifolia, Datura stramonium, Erigeron annuus, Galinsoga ciliata, Reynoutria japonica, Solidago gigantea, and Sorghum halepense. Multivariate statistical methods such as cluster and PCA were performed to determine possible connections and correlations among selected IAS depending on the phytochemical content. According to the obtained results, R. japonica was notable with the highest content of vitamin C (38.46 mg/100 g FW); while E. annuus (1365.92 mg GAE/100 g FW) showed the highest values of total polyphenolic compounds. A. retroflexus was characterized by the highest content of total chlorophylls (0.26 mg/g) and antioxidant capacity (2221.97 µmol TE/kg). Therefore, it can be concluded that the selected IAS represent nutrient-rich plant material with significant potential for the recovering of bioactive compounds.

This paper presents an invasive plant species that occur in the forests of Kalnik. It also presents the state of the distribution and their impact on forests of Kalnik. A total of 14 invasive species in the forests of Kalnik and these are – Acer negundo L., Ailanthus altissima (Mill.) Swingle, Ambrosia artemisiifolia L., Amorpha fruticosa L., Asclepias syriaca L., Conyza canadensis (L.) Cronquist, Echinocystis lobata (Michx.) Torr. et Gray, Erigeron annuus (L.) Pers., Impatiens glandulifera Royle, Juncus tenuis Willd.), Phytolacca americana L., Reynoutria japonica Houtt., Robinia pseudoacacia L., Solidago gigantea Aiton. Alochtonous vegetation is not only inevitable, but it also appears to be a constant future challenge in the globalizing world which communicates on all levels with every means possible. Its influence should not by any means be marginalized. Its importance and influence is not completely negative and there are possible benefits and dangers which should be controlled by the preventive measures and physical regulation. The most important species in Kalnik forest vegetation is definitely acacia. It is especially important for private forest lands where acacia tree has become very popular because of its characteristics as a fast growing tree species without any special requirements with relation to growth and it gives fast results concerning timber and firewood. Private lots are usually very small and fragmented. There is a growing need for timber, therefore the trees are grown extensively, from stumps and roots. Other woody species still do not pose a serious threat in economical or biological sense. The impact of herbaceous plants differs in various areas. The most problematic issues for the forestersare thick layers of unwanted specieswhich grow in young forest stands or in forests in the phase of restorationwhere these unwanted speciesinvasively compete with autochthonous species. In biological sense, invasive species pose a constant threat not only to domestic vegetation and biodiversity, but also to human health. We should also mention apiculture, a very important and well developed activity on Kalnik. Above mentioned species are very important and interesting for apiculture as a type of rich bee pasturage. Apiculture in this area depends on acacia pasturage and it is one of very important reasons for growing acacia tree. Other tree species are also valuable for bee pasturage, especially late in autumn when there is no other bee pasturage available and they are mostly species which blossom in autumn and represent a valuable source of pollen (Japanese Knotweed, Prickly cucumber and European goldenrod). Generally speaking, the biggest responsibility for possible consequences of invasive plant species to the vegetation of Kalnik lies on foresters who have to recognize and monitor the appearance of invasive species, especially in state forest lands where they grow and directly influence their composition and state.

Background and purpose: The objectives of our study were to identify invasive alien plant species (IAS) in the main Natura 2000 forest habitat types (FHT) along the Mura River in Slovenia, and to estimate their abundance and cover. The aim of our study was to find out a) What kinds of IAS appear in the research forests? b) What is their frequency and cover percentage? c) Are individual IAS more attached to some FHT than others? d) What is the correlation between the cover of IAS and the tree layer cover?Materials and methods: We analysed the fidelity of invasive plant species to individual FHT. The studied FHTs along the Mura River were following: 91E0* (Alluvial forests with Alnus glutinosa and Fraxinus excelsior), 91F0 (Riparian mixed forests of Quercus robur, Ulmus laevis and Ulmus minor, Fraxinus excelsior or Fraxinus angustifolia, along the great rivers) and 91L0 (Illyrian oak-hornbeam forests). Two forest areas of about 600 ha were studied in total.Results: 16 IAS were recorded in studied FHTs. Some species, like Robinia pseudacacia, Impatiens glandulifera, I. parviflora, Fallopia japonica (incl. F. x bohemica), Erigeron annuus, Ambrosia artemisiifolia, Amorpha fruticosa, Conyza canadensis and Juncus tenuis occur only in one or two FHTs, while some species can be found in all studied FHTs (like Solidago sp.). We have found that the most threatened forests are those with prevailing Salix alba, Alnus glutinosa, Fraxinus angustifolia and Ulmus laevis, tree species, which grow closest to the river and on the wettest sites.Conclusions: The increasing presence of IAS in the study areas seriously affect natural regeneration, stability, and continuity of floodplain FHTs. Therefore, some measures and guidelines for managing of these forests are suggested in this study.

The research carried out in Olt County regarding invasive and potentially invasive alogen plant species is a necessary step in order to complete the information on their distribution at the national level. The data obtained will be able to be used for a careful monitoring of these plants and the adoption of the necessary management measures regarding the eradication or prevention of their introduction and spread.
 In this sense, an inventory of invasive and potentially invasive plant species identified on the territory of Olt county is presented, with information on the geographical origin, life form, biological form, an assessment of the degree of invasiveness, chorological data, habitat, as well as aspects related to the impact they exert on native vegetation, human health or the economy.
 The preliminary analysis of the list of invasive and potentially invasive alogen plants identified in Olt County highlights, in particular, the presence of some species of concern for the European Union (such as Ailanthus altissima, Asclepias syriaca and Elodea nuttallii). Besides these, the most widespread invasive species found in Olt county are Ambrosia artemisiifolia, Robinia pseudoacacia, Morus alba, Amorpha fruticosa, Acer negundo, Amaranthus retroflexus, Erigeron annuus, E. canadensis, Lycium barbarum, Sorghum halepense, Xanthium orientale subsp.italicum. It is well known that the impact of invasive species on the environment, the economy and in some situations even on human health is major and that is why these organisms must be subject to an extensive and continuous monitoring process. Also, in order to control the introduction and spread of invasive and potentially invasive species, a series of appropriate management measures are required.

Paukova Ž.: Invasive plant species in the three microregions of Nitra region, south-west Slovakia. Ekologia (Bratislava), Vol. 32, No. 2, p. 262-266, 2013. Alien plant species were recorded by field survey in three selected microregions (submontane in district Zlate Moravce, hilly in district Nitra and lowland in districts Nove Zamky) in Nitra region, SW Slovakia in 2011. In the microregions totally 19 invasive neophytes were recorded. The most frequent and abundant species were the following: Ailanthus altissima, Ambrosia artemisiifolia, Conyza canadensis, Fallopia x bohemica, Helianthus tuberosus, Iva xanthiifolia, Negundo aceroides, Robinia pseudoacacia, Solidago canadensis and Stenactis annua. On the basis of the data we can preliminary conclude that the number of species and the number of localities in the southern lowland microregion were almost twice higher than those in the northern hilly region.

Invasive plants threaten not only natural habitats but also the native weed associations of the agricultural land. The segetal (arable) weed vegetation in Hungary has changed greatly in recent decades, mainly through the decrease of diversity of arable field flora. This study deals with the role of invasive weeds in transforming the segetal weed communities in South Hungary. It can be stated that these invasives have a serious transforming effect on the natural arable weed associations. Some of the investigated plants and their frequency in the examined region are common ragweed (84%), horseweed (22%), annual fleabane (14%), johnsongrass (36%), and Italian cocklebur (7%). These plants were all frequent and dominant on the studied area, both on arable land and in vineyards. Some of the weed associations already bear the names of these community-forming species.Nomenclature: Annual fleabane, Erigeron annuus (L.) Pers. #3 ERIAN; common ragweed, Ambrosia artemisiifolia L. # AMBEL; horseweed, Conyza canadensis (L.) Cronq. # ERICA; Italian cocklebur, Xanthium italicum Moretti # XANIT; johnsongrass, Sorghum halepense (L.) Pers. # SORHA.Additional index words: Arable weed flora, impoverishment, invasive weeds, segetal weed vegetation.

Ecological impact of phytoinvasions in Ukraine

A survey of species and distribution of exotic weeds was conducted with the square plot method in different habitats in Nanjing. The collected data were analyzed with principal component analysis(PCA). Twenty one exotic weed species belonging to 19 genera and 11 families were recorded in autumn in the region, and of them originated from America. Composite comprised the most species among all families. The results of principal component analysis showed that the most important factors affecting the occurrence and distribution of exotic weed species were the levels of human disturbance and soil humidity. According to these two factors, all samples were divided into four groups. The dominant exotic weed species in each group were regarded according to the importance value of the species. Group I included samples collected from dry land, and its dominant exotic weed species were Amaranthus retroflexus, Veronica persica and Alternanthera philoxeroides . Group Ⅱ included samples located in wastelands and right of ways which were non managed or non irrigated farmland. The dominant exotic weed species mainly belonged to composites, such as Erigeron annuus, Conyza bonariensis and Conyza canadensis . Group Ⅲ included samples located in public parks where the number of exotic weed species was abundant. The dominant species were Ambrosia artemisiifolia,Plantago virginica,Alternanthera philoxeroides,Aster subulatus,Erigeron annuus,Conyza bonariensis , and Conyza canadensis . The last group was mainly composed of samples distributed on the waterside and in paddy fields. The dominant exotic weeds were Alternanthera philoxeroides, Aster subulatus and Medicago hispida . The analysis of the difference of species richness among groups showed that invasion of exotic weeds had a harmful influence on biological diversity. Some suggestions for management of exotic weeds are proposed.

Till now in Northern Germany neophytic plant communities were hardly noted. In the present paper the sociology of the following species is investigated for the first time for the south-eastern part of Lower Saxony: Anstolochia clematitis, Aster lanceolatus, Aster tradescantu, Claytonia perfoliata, Erigeron annuus, Helianthus tuberosus, Impatiens parviflora, Parietaria officinalis, Reynoutria japonica, Rey-noutria sachalinensis, Solidago canadensis, Solidago gigantea and Tulipa sylvestris. To classify the often character-speciesless communities the deductive method of KOPECKY & HEJNY is used. Most of these neophytic plants have their chief importance in skirt communities of the order Galio-Caly-stegietalia, first of all in Aegopodion and Lapsano-Geranion. In contrary to the western and southern parts of central Europe they are hardly no object in bank eommunities. Their occurrence accumulates in ancient towns, especially like Brunswick. The rieh Stands of Parietaria officinalis and Tulipa sylvestris in Brunswick should be shown off here. During this work, the great importance of ancient parks for pro-tection of species turned out: Numerous species are able to hold their ground in the border of bushes. Solely the spreading of Solidago gigantea and Solidago canadensis has taken a threatening extent: At edges of the forests both Solidago species penetrate into native plant communities and destroy them. De-positing ofgarden refuse is the main reason of their quiek spreading. A list of plant communities belonging to the classes Artemisietea till now known for the eastern part of Lower Saxony is presented; probably it is valid for whole Lower Saxony.

The areas covered by alien plants in Europe have expanded during recent years. Romania ranks 17th out of all European countries, with 740 allochthonous species. Most of these plants are classified as neophytes (703), the rest being archaeophytes (23), or archaeophyte-neophytes (14). The analysis of alien plants on the territory of Dolj County led to the identification of 160 taxa that belong to 49 botanical families. The best represented family is Asteraceae, with 30 taxa. There is a significant gap between the family holding the first position and the following two, i.e., Amaranthaceae, with 11 taxa and Fabaceae, with 10 taxa. Even though almost half of the families with identified alien plant species have only one representative, the reality in the field shows a completely different image, as the populations of the respective taxon are abundant (e.g., Phytolacca americana, Ailanthus altissima, Acer negundo, Asclepias syriaca, etc.). The analysis of the plant inventory revealed the presence of certain invasive taxa (Ambrosia artemisiifolia, Erigeron canadensis, Vallisneria spiralis, Erigeron annuus, Robinia pseudacacia), which found good development conditions on the territory of Dolj County. Some of them are of interest to the European Union (Asclepias syriaca, Ailanthus altissima, Elodea nuttallii). Climate changes occurred during recent years, associated with human activities in all domains, have led to obvious transformations in the chorology of some alien species on the territory of Dolj County. Xerophilous, thermophilic, heliophilous, and anthropophilic species (e.g., Abutilon theophrasti) are favoured.

Invasive allochtone species cause the degradation of the natural habitats they invade through the negative impact they have on native plant communities, which they tend to alter, even replace, through their increased competitiveness and their high potential for reproduction and spread. The main objective of the study was to identify and evaluate the spread potential of allochtone invasive species observed in some habitats of European interest in the Pesceana river basin (Vâlcea county), starting from the quantitative evaluation of their populations within the plant associations specific to different types of habitats. The assessment of invasive species was carried out by determining the number of individuals and assessing the percentage abundance-dominance of these species in relation to the total abundance-dominance of the species in the plant associations specific to the different types of analyzed habitats. Observations were carried out in the following types of habitats affected by different allochtone invasive plants: habitat 91M0 Pannonian-Balkanic turkey oak-sessile oak forests; habitat 9130 Asperulo-Fagetum beech forests; habitat 91Y0 Dacian oak & hornbeam forests; habitat 9170 Galio-Carpinetum oak-hornbeam forests; priority habitat 91E0* Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae); habitat 6430 Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels and habitat 3150 Natural eutrophic lakes with Magnopotamion or Hydrocharition – type vegetation. The primary factor that significantly contributed to the introduction and rapid spread of these plant species in the analyzed habitats was zoo-anthropogenic. Among the invasive plant species that affect the floristic composition of the plant associations in the assessed habitats, the most frequent were: Erigeron canadensis, Ambrosia artemisiifolia, Robinia pseudoacacia, Erigeron annuus subsp. strigosus, Xanthium orientale subsp. italicum, Elodea nuttallii and Ailanthus altissima, all being classified as neophytes. Interpretation of the field date showed that the most affected types of habitats were 91E0* and 6430 and the most affected plant associations, depending on the share of invasive plant species, were Aegopodio podagrariae-Alnetum glutinosae Karpati et Jurko 1964, respectively Scirpetum sylvatici Ralski 1931 em. Schweich. In the case of the association Aegopodio podagrariae-Alnetum glutinosae Karpati et Jurko 1964, the percentage values of the abundance-dominance of the invasive species are very high compared to the value of the total abundance-dominance of the component species, which denotes a high degree of damage and the high potential of dissemination to the associations adjoining plants and to other similar types of habitats.

Floristic composition of the weed community in apple orchards differs, depending on the type of management - extensive or intensive. In extensive orchards, weedy-ruderal-grassland species are dominant. On the other hands, in intensive orchards the inter-row can be dominated by annual (therophyte) weed species, if mechanically cultivated, or grass species, if grasses are used as cover crops, while the rows are dominated by perennial weed species (geophytes, hemicryptophytes). The floristic composition of the weed communities is also dependent on the age of the orchard. In younger orchards row crop weeds are dominant, while as the orchard ages, the community gets a more weedy-ruderal-grassland character. The most common weed species in apple orchards in Serbia are: Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album, Convolvulus arvensis, Carduus acanthoides, Cynodon dactylon, Erigeron canadensis, Hordeum murinum, Lamium purpureum, L. amplexicaule, Medicago lupulina, Setaria spp., Stellaria media, Stenactis annua, Sonchus arvensis, Taraxacum officinale, Veronica spp. and Vicia spp. Weed control in apple orchards can be done using agrotechnical (soil cultivation), physical (mowing, mulching), thermic, chemical, biological measures, and by growing cover crops. In practice, weed control in apple orchards is dominantly done by herbicides, based on the following active substances: napropamide, glyphosate, 2.4D, flazasulfuron, flurochloridone, cycloxydim, fluazifop-p-butyl, clethodim, diquat, fluroxypyr-meptyl, and pyraflufen-ethyl. Given that nowadays the production of healthy and safe food is an imperative, also demanded by the international market, it is expected that bioproducts will be prioritized over classical synthetic herbicides. Moreover, non-chemical measures are also becoming more important as part of integral weed control measures of weeds in apple orchards.