Composition and phytotoxic activity of the essential oils of two invasive plant species

Alien species have been entering Europe for centuries. Their numbers have risen exponentially. Invasive species have multiple negative ecological, economic and human-health impacts. Chemicals produced by alien species are allelopathic to native species which are less resistant to them. This effect probably enables alien species to spread to new areas [1]. The possible use of natural compounds in weed management has been well documented [2,3].                Our research focused on two invasive species–Heracleum mantegazzianum Sommier et Levier (Apiaceae, giant hogweed) and Impatiens parviflora DC. (Balsaminaceae, small balsam). Giant hogweed produces a large number/amount of chemical compounds, such as coumarins and esters [4]. Many groups of active compounds have been isolated from different species of the genus Impatiens [5]. However, only few reports are available concerning the volatile constituents of both species.                The aim of the present experiment was to determine the quantitative and qualitative properties of the essential oils (EOs) hydrodistilled from the two invasive species. The phytotoxic effect was tested on selected dicotyledonous plant species. Different biological effects were evaluated in different concentrations of EOs

Právní důsledky uplatnění námitky svědomí proti povinnému dětskému očkování v České republice

This paper analyses legal consequences of applying conscientious objections to childhood mandatory vaccinations in the Czech Republic. There is no common European approach towards childhood vaccination and legal exemptions from statutory duty imposed by part of the states. The European Court of Human Rights considers vaccination campaigns which oblige individual to defer to general interest and not to endanger health of others where his own life is not in danger, not going beyond the margin of appreciation left to the state by Art. 8 (2) of the European Convention on Human Rights. Still, the Constitutional Court of the Czech Republic found in its recent case law conscientious objections to be under certain circumstances a good reason for refraining from punishing parents waiving compulsory vaccination of their children for committing administrative delict. This paper focuses not only on the test the Constitutional Court chose to apply to distinguish between cases of sincere objections and mere free-riders, but also on broader reasons of liberal state tradition that led the Constitutional Court to allow for such exemptions. In addition, nature of statutory condition of due vaccination for accepting a child for preschool education is analyzed. The paper argues that it is not a sanction and finds a parallel with exemptions from compulsory military service conditioned by serving an alternative service contributing to public good.Článek analyzuje právní důsledky uplatňování námitky svědomí vůči povinnému dětskému očkováním v České republice. K očkování dětí neexistuje žádný společný evropský přístup a rovněž tak ani vůči podmínkám osvobození od zákonné povinnosti uznávaným některými státy. Evropský soud pro lidská práva považuje očkovací kampaně, kdy státy ukládají jednotlivcům povinnost, aby se podřídili celospolečenskému zájmu na proočkovanosti a neohrožovali zdraví ostatních, není-li jejich život ohrožen, za zásah do práva na soukromí, ke kterému jsou v souladu s čl. 8 odst. 2 Evropské úmluvy o lidských právech. Ústavní soud České republiky však ve své nedávné judikatuře dospěl k závěru, že za určitých podmínek námitky svědomí mohou být dostatečným důvodem k tomu, aby stát měl povinnost zdržet se potrestání rodičů, kteří nesplnili povinnost očkovat své děti, za spáchání přestupku. Tento příspěvek se zaměřuje nejen na podmínky, které se Ústavní soud rozhodl uplatňovat, aby rozlišoval mezi případy upřímných námitek a pouhými svobodnými jezdci, ale také na širší důvody liberální státní tradice, které vedly Ústavní soud k tomu, aby umožnil takové výjimky. Kromě toho je analyzován charakter zákonnosti požadavku absolvování řádného očkování pro přijetí dítěte k předškolnímu vzdělávání. Článek argumentuje, že rozhodnutí o nepřijetí k takovému vzdělávání není sankce a nalézá paralelu s osvobozením od povinné vojenské služby podmíněnou poskytováním alternativní služby přispívající k veřejnému blahu

Invasiveness of <i>Impatiens parviflora</i> in Carpathian Beech Forests: Insights from Soil Nematode Communities

Invasive plants are capable of homogenizing both aboveground and belowground biota and, along with climate change, are recognized as one of the biggest threats to global biodiversity. Soil nematode communities reflect the surroundings they inhabit and are therefore frequently employed as biological indicators of soil condition. In this study, soil properties and nematode communities in Carpathian beech forest floor covered by dense vegetation of invasive Impatiens parviflora (small balsam) were investigated over two vegetation seasons. We assumed that the spread of invasive I. parviflora could influence soil fauna through litter accumulation when established and could also change several soil properties, consequently altering soil nematode communities. A total of 52 nematode species were found in the soil samples. The mean number of species varied from 18 to 31, but did not significantly differ between invaded and uninvaded plots across all sampling dates. However, redundancy analysis indicated that the nematode community in plots with small balsam differed significantly from that in uninvaded plots, reflecting different proportions of genera in the two communities. Invasion by small balsam significantly enhanced the relative abundance of bacterivores, whereas it decreased the abundance of plant parasites and root-fungal feeders, mainly in the spring and summer season. Ordination of nematode species along the structure index and enrichment index trajectories revealed a maturing food web, low to moderately disturbed in the I. parviflora invaded soils as well as in uninvaded forest plots. Decomposition channels of soil food webs in both plots were balanced and fungal–bacterial mediated, although low values of the channel index suggested prevailing bacterial decomposition. Our study reveals that the expansion of I. parviflora moderately influenced the composition of nematode communities and the soil food web, increased soil nitrogen, carbon and C/N ratio, but did not modify soil acidity

Long-Term Giant Hogweed Invasion Contributes to the Structural Changes of Soil Nematofauna

Heracleum mantegazzianum (giant hogweed) is the largest central European forb, naturalized or invasive in many European countries. The impacts of its colonization of native habitats on soil mesofauna groups are unfortunately obscure. This study assessed the effect of giant hogweed invasion on the communities of plants and soil nematodes in the riparian habitat. We found that invasion by H. mantegazzianum increased soil pH, decreased carbon and nitrogen content, reduced the number and coverage of the native plant species, and influenced nematode communities and their structures. Nematode species number was significantly lower in invaded than uninvaded plots, but nematode species diversity was not affected by invasion throughout the whole study. Total nematode abundance slightly increased under giant hogweed, while total nematode biomass did not differ between the invaded and uninvaded plots. The higher abundance of bacterivores and fungivores but lower number of omnivorous nematodes well represented the negative impact of giant hogweed invasion on soil food webs, supported by low values of all maturity indices or channel index. The hogweed invaded plots contained higher abundance of plant parasitic nematodes, mainly Paratylenchus microdorus. Our results thus indicate that invasion by H. mantegazzianum influences several nematode communities’ parameters while others remain unaffected by invasion

Phytotoxic Effect of Invasive <i>Heracleum mantegazzianum</i> Essential Oil on Dicot and Monocot Species

Spreading of the plant species in new areas is supported by the hypothesis in which chemicals produced by alien species are allopathic to native plants. A novel weapon hypothesis was tested by using essential oil of dangerous alien species Heracleum mantegazzianum in laboratory conditions. Aboveground plant material was collected in south-east part of Slovakia, dried and hydrodistilled for essential oil isolation. Dominant compounds as octyl acetate (62.6%), hexyl 2-metylbutyrate (10.7%), hexyl isobutyrate (7.5%) and hexyl butyrate (6.5%) were identified by GC-MS. Potential phytotoxic activity was tested on three dicot plant species garden cress (Lepidium sativum L.), radish (Raphanus sativus L.) and lettuce (Lactuca sativa L.) and on one monocot plant species wheat Triticum aestivum L. Germination of the seeds of model plant species after influencing by different doses of essential oil of H. mantegazzianum as well as the roots length was evaluated. Lepidium sativum L. and Raphanus sativus L. were generally not sensitive to applied doses of essential oil although a little stimulation effect at some concentrations prevailed over inhibition effect. Similarly, in monocot species Triticum aestivum L., stimulation was visible in both root length and root number at two or one highest doses, respectively

Potential Phytotoxic Effect of Essential Oil of Non-Native Species Impatiens parviflora DC.

Impatiens parviflora is non-native invasive plant species occupying large areas all over the Europe and threatens native communities by altering their species composition and reducing native biodiversity. The factor responsible for its spreading could be explained by releasing biochemical to the environment. On the other hands, high demand on secondary metabolites as potential source of new ecofriendly biocides could be beneficial. The analysis of I. parviflora essential oil (EO) led us to identify more than 60 volatiles. The main compound was hexahydrofarnesyl acetone, other dominant components were phytol, carvacrol, germacra-4(15),5,10(14)-trien-1-&alpha;-ol, and pentacosane. The potential phytotoxic effect of I. parviflora EO collected in two vegetation periods (summer and autumn) was evaluated on seed germination and root elongation of three dicot species (Raphanus sativus, Lepidum sativum, and Lactuca sativa) and on one monocot species (Triticum aestivum). The seed germination of only one dicot species, L. sativa, was affected by both EOs. In contrast, seed germination of monocot species T. aestivum was influenced only by the highest doses of EOs isolated from I. parviflora in autumn. The root elongation of tested plant species was less influenced by I. parviflora EOs. L. sativum showed sensitivity to one dose of EOs hydrodistilled in summer, while the monocot species was influenced by both EOs samples in highest doses. Our findings revealed that I. parviflora contained phenolics that were phytotoxic to the germination of some plant species, mainly at higher EOs doses, while root elongation of tested plants was not suppressed by essential oils