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The aim of the work was to estimate the range of morphological variability of seeds of the Himalayan balsam (Impatiens glandulifera), from different sites within Poland. It was also verified whether there was a correlation between morphological variability of seeds and type of vegetation from which they originated. Additionally, the seed coat ultrastructure of this species was studied. Biometrical analysis showed remarkable variability of seed morphology. A significant relationship between seed size and type of vegetation was also revealed. However, there was no clear relationship between seed mass and type of vegetation. Based on the structure and ornamentation of epidermal cells, the rugosely ruminate seed coat type was proposed.
Positive correlation between seed weight and germination capacity is common for the vast majority of species. It is also known that seed weight can vary along a latitudinal gradient. The seed mass of the invasive Himalayan balsam (Impatiens glandulifera), which is native to East Asia, was examined in relation to distinct geographical regions in Poland (Bielsko-Biala: N49°52′32″, E18°57′43″; Katowice: N50°12′8.3″, E18°57′26″; Tworków: N50°01′22″, E18°15′28”); Hungary (Rum: N47°06′41″, E16°50′45″; Rábahídvég: N47°03′54″, E16°44′59″) and Germany (Halle: N51°28′47″, E11°57′12″; Marburg: N50°48′32″, E8°46′31″). The study revealed that seed mass varied both among the countries and among specific populations within Poland and Germany. In Hungary, the 50 seed lots were the lightest 0.29 g and 0.31 g in respective localities and the heaviest in single populations in Poland – 0.61 g and in Germany – 0.57 g. In the present study, populations located more southwards had the lightest seeds in contrast to the commonly encountered pattern. Higher temperature, lower precipitation and as a consequence, a shortage of water can be crucial factors that affect the seed mass of I. glandulifera. Taking into account the lower frequency and abundance of the species in Hungary, the lower seed mass may probably contribute to the limited distribution range in this region.
Invasion of Impatiens glandulifera was reconstructed along rivers in the Czech Republic, central Europe, based on floristic records. The occurrence was assessed along river banks, outside the river banks, and along tributaries downstream from the first records of the species in 1902, 1903, 1978 and 1995, respectively. The following main results were obtained: (a) The species nowadays occupies 77% of the river length in the country. (b) The rivers, investigated in detail, did not differ in the occurrence of the species along the river banks. (c) There were some significant relationships between the penetration of I. glandulifera far from the river banks both in terms of the lateral dimension in the main valley, and upstream along the tributaries, and the time of the first occurrence of the species on the river. (d) It took approximately 20 years from the first occurrence on the main river and the start of spread along the tributaries. The process of invasion is still in progress after about one century and further spread is expected.
River valleys of the Sowie Mts and the Dzierżoniowska Basin, due to human long-term agricultural activity, were heavily transformed. Disadvantageous changes of river systems simplified penetration by invasive species. They make a serious problem to plant diversity, are burdensome to citizens, increase the threat of flooding and lower the beauty of landscape. In the middle 70-ties of 20th century, knotweed and Himalayan balsam were noticed in the Sowie Mts. In 2006 field research enabled to estimate the condition of their populations and regularity of their occurrence along the rivers near Bielawa.
The paper presents the results of several years investigations (2003-2007) on two invaders: the Himalayans Impatiens glandulifera and Asiatic Reynoutria japonica. The Sudety Mountains and their national parks are under strong pressure of both species, threatening the local vegetation. The four-year investigations have been carried out in field, glasshouse and in laboratory. Invasive species have their peculiar life histories which help them to occupy new areas. Those are above all the specific generative reproduction strategies (Impatiens) or vegetative reproduction strategies (Reynoutria). Both strategies secure the reproductive success and to capture more and more highly situated areas of the mountains. Very significant characteristics connected with the expansion of invaders is the excessively over and above the average production of seeds (Impatiens) and a huge annual increment aboveground biomass (Reynoutria). The investigated invasive species are probably not equipped with influence of allelopatic type as of greater importance is their competitive strength. The invaders can eliminate a part of the early spring flora belonging to the geophyte group and impoverish the regional biological diversity. Both the invasive plants enter also into some moist mountain forest communities.
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