Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 35

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  floristic diversity
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Species composition of lawns in the housing estates, planted – among other reasons – in order to diversify the urban landscape, is often modified and enriched with other, spontaneously appearing species. The aim of the present work was to determine the floristic and phytosociological diversity of selected housing estate lawns of three different age groups, in the city of Szczecin, in three neighbouring housing estates (Niebuszewo, Warszewo, and Żelechowa). It was assumed that over the years, lawns are gradually becoming weaker, which may be due to the occurrence of negative anthropogenic factors of increasing intensity. It was found that despite the one designated plant community in all the analysed housing estate lawns (namely, Poa pratensis – Festuca rubra), there are differences between the studied areas, in terms of the number of species occurring therein, and the values of selected ecological (environmental) indicators.
The aim of this study was to determine floristic diversity, the chemical composition, nature value and energy value of selected sedge communities in view of habitat conditions in the Noteć valley. This study was based on a total of 46 relevés prepared according to Braun-Blanquet. The identified communities were represented by common plant associations, both natural or semi-natural. They comprised mainly vegetation of meadows excluded from agricultural use, on fresh and partly moist and very moist soils, of weak acid and neutral reaction. Analysed communities had moderate or high nature value. Sedges and Cyperaceae predominated in their structure, with the greatest share of Caricetum lasiocarpae (76%) and the lowest share of Caricetum distichae (44.6%). No Fabaceae were reported in any of the two plant associations, while herds were found in all associations. The greatest higher heating value and lower heating value were found for communities with Carex lasiocarpa and Carex disticha.
Changes in the floristic composition of meadows and pastures may provide information on the human impact on the habitat conditions and intensity of land use. The aim of the study was to present the floristic diversity of the Lolio-Cynosuretum association and its relation with the habitat conditions evaluated using the phytoindication method with Ellenberg indicators. The study was conducted in five river valleys in the years 1999-2012. For the analysis, 100 relevés were selected, which were subject to floristic, habitat (phytoindication), and statistical analysis. In the Lolio-Cynosuretum phytocoenoses, the total number of 178 taxa of vascular plants from 33 families was recorded. It was demonstrated that the differentiation in the floristic composition of Lolio- -Cynosuretum phytocoenoses remains in relation with the habitat conditions, which may be evaluated basing on the ecological preferences of plant species that form the taxa. The species were established as differential for the lower units, that is four subassociations and eight variants.
The vascular flora in the “Łąki w Komborni” Natura 2000 site comprises 219 species representing 44 families and 147 genera. Species from the families Asteraceae, Poaceae, Lamiaceae, Fabaceae, Rosaceae, Polygonaceae, Cyperaceae, Apiaceae, and Ranunculaceae were found to dominate. A geographical and historical analysis of species confirmed the clear dominance of apophytes (84%) over anthropophytes (16%) as well as perennials (69%) over short-lived (23%) species. The biological spectrum was dominated by hemicryptophytes (54%) and therophytes (19%), compared with other life forms. In terms of synecology, the flora was mainly represented by species from the classes Molinio-Arrhenatheretea, Stellarietea mediae, Artemisietea vulgaris and Phragmitetea. The “Łąki w Komborni” site is a habitat for 82 (37%) medicinal species and 155 (70%) forage species for bees. Noteworthy is the occurrence of protected species, e.g. Gladiolus imbricatus, Trollius europaeus, Centhaurium erythraea, Dactylorhiza majalis, Platanthera bifolia and Primula elatior.
Open-cut excavations formed as a result of exploitation of mineral deposits are the least studied ecological sites. Habitat heterogenity is reflected by remarkable floristic and phytocoenotic diversity. Being isolated by the surrounding vegetation of contrasting types – they can be considered as “habitat islands”. Twenty excavations (area from 100 m² to 2 ha) were selected – 10 located in cropland, 10 – in coniferous forest. The intensiveness of gravel pit exploitation was differentiated. Some of them were exploited, other ones were abandoned 10–30 years ago. The floristic records were taken during summer period in each pit and in near-by vegetation at the distance not larger than 200 m. As much as 280 species of vascular plants were found in 10 selected gravel pits surrounded by coniferous forest communities, which contained only 111 taxa. The flora of mid-field excavations was definitely richer that the flora of their surroundings. Sörensen’s similarity index (So ) for mid-forest gravel pits and their surroundings ranged between 27% and 40% while that for midfield gravel pits and their neighbourhood – from 15% to over 27%. The U Mann-Whitney test demonstrated that the number of species noted in selected gravel pits significantly differed from that in the surrounding. It was true for both (mid-forest Z = 3.70; P = 0.00021) and mid-field gravel pits (Z = 3.78; P = 0.00016). Native species were dominating in the flora of both mid-field and mid-forest excavations (77% and 82 % respectively). Hemicryptophytes were found to dominate (46%) over other groups of life forms in both types of gravel pits. A high contribution of terophytes – over 19% in mid-forest excavations and over 25% in mid-field ones is noteworthy. The results showed that gravel pits could play a role of enclaves for natural and semi-natural vegetation thus acting as local centres of floristic diversity in human modified monotonous agricultural or monospecies pine forest landscape.
The montane glades in the Polish Carpathians were created centuries ago and have lasted mainly as a result of mowing and grazing. The observed abandonment of traditional methods of tillage in the last century led to adverse changes in vegetation cover, including a decrease in floristic diversity and the disappearance of many plant species and associations. One of a rare mountain taxa in Poland is the alpine globeflower Trollius altissimus Crantz. The investigations were carried out between June and September 2014 in the Hala Długa glade (Gorce Mts.) at two 36 m² plots: extensively grazed (P1) and unmanaged (P2). Light intensity, abundance and density of individuals and ramet clusters were significantly greater in the extensively grazed plot, whereas height of plant canopy, length of basal leaf petioles, width of leaf lamina, number and length of generative stems, number of flowers and follicles achieved higher values in the unmanaged plot. The structure of developmental stages and number of basal leaves did not differ remarkably between the studied sites. Also, the soil properties in both plots were very similar. The studies show that extensive sheep grazing has a positive influence on Trollius altissimus. In the studied locality such management contributes to the gradual spreading of this species. However, too intensive pasturage might eliminate this species as it has never been observed in any of the permanently grazed patches in the vicinity.
Shrub development on road outside verges can provide alternative wildlife habitat. However, management of inside verges should keep vegetation at a height consistent with proper road visibility and safety. The influence of management on vegetation was analyzed on the inside verge of two Portuguese roads, one mown once and another twice a year. Specifically, the effect of mowing frequency on shrub abundance and the combined effect of management and shrubs on floristic diversity were addressed. One stretch of each road was surveyed for shrub abundance and for herbaceous species diversity and cover. The effect of mowing frequency on shrub growing and biomass production and allocation was also evaluated along two years. Results indicate that vegetation mowing yearly in spring is enough to keep the inside verge free from most shrubs. However, summer growing shrubs like Dittrichia viscosa can persist, decreasing both floristic diversity and cover, particularly of meadow species. Moreover, in response to spring mowing, shrubs grew fast and were able to disperse efficiently. An additional autumn mowing significantly decreased not only shrub height and canopy area, but specially seed production and dispersal. Thus, the inside verge management should be based on two mowing periods. The first in spring to control winter and spring growing species, and an additional autumn mowing to control growth and dispersal of summer growing shrubs and trees, or even tall grasses. This management regime will combine safety with improvement of the amenity and habitat value of the road verges.
Trawniki zakładane w miastach wzbogacają się z czasem o gatunki pojawiające się spontanicznie. Aby określić zróżnicowanie tych muraw, wykonano badania fitosocjologiczne. Wśród trawników wyróżniono trzy grupy: osiedlowe, przyuliczne i parkowe różniły się one składem gatunkowym oraz występującymi zbiorowiskami. W runie odnaleziono aż 224 gatunki, w tym 53 na trawnikach osiedlowych, 190 na przyulicznych i 105 w parkach. Pomimo trudności z przyporządkowaniem występujących na trawnikach zespołów do jednostek fitosocjologicznych wyróżniono 9 zbiorowisk należących do zespołów synantropijnych i muraw deptanych. Zróżnicowanie muraw trawnikowych zależne jest od siedliska, zajmowanej powierzchni oraz oddziaływania człowieka (pielęgnacji i deptania). Duże zróżnicowanie jest korzystne pod względem ekologicznym i estetycznym.
Plantations of energy plants are the alternative form of post-agricultural and degraded land management. Particularly, small-area plantations of the tree species, including the willow Salix sp., raise local natural values of degraded habitats and are a dwelling place for numerous entomofauna, birds and mammals. Herbaceous vegetation accompanying short-rotation coppice (SRC) constitutes at the beginning a competition for energy species plantings and therefore is subject to chemical and mechanical control. In successive years, it may increase local biodiversity at the level of plant species and associations, both in ruderal habitats and extensively used agricultural lands. In the presented paper, results of the study referring to evaluation of the floristic and phytosociological diversity of herbaceous vegetation accompanying selected 4–5-year-old willow short-rotation coppices (SRC) situated on lands adjacent to the Odra River estuary (Western Pomerania) in different soil-habitat conditions are showed. Investigations were carried out in willow SRCs located on degraded sandy silts and sewage sludge-fertilised silts, fallow post-farmland and degraded grassland. The largest number of species onfirmed by the highest Shannon-Wiener’s diversity index (H) and species evenness index (J) was characteristic of SRCs set on sandy silt fertilised with sewage sludge, wet grassland and fallow post-farmland when compared to those on sandy silt and over-dried grassland. The analysis of vegetation showed a strong predominance of anthropogenic associations (synanthropic and seminatural) over autogenic (natural) ones.
Results of the studies on the floristic biodiversity of the kurgans in the Pontic desert steppe of the Black Sea Lowland (Kherson Region) are presented. Twenty-six of about 130 kurgans higher than 3 m, distributed over an area of approx. 1500 km2, were surveyed and the flora of 5 microhabitats within every kurgan (top, southern and northern slope, southern and northern foot) was examined. The richness of the kurgan flora is estimated at 305 species. Species of alien origin constituted 23% of the total flora, which indicates limited anthropogenic influence. Species of two classes, Festuco-Brometea and Stellarietea mediae were predominant, which also confirmed the semi-natural character of the kurgan flora. The lowest number of species was recorded on top, which was relatively rich in synanthropes, particularly therophytes (Stellarietea mediae). The north side was richer in species than the south side of the kurgans. Steppe species were the most stable and important component of the flora of the slopes (45-47% of the species represented the class Festuco-Brometea). The total flora of the foot contained more species and was more diversified than the flora of the slopes (although the mean number of species was similar in both habitats), but each species occurred at low frequency. There was a higher proportion of species which were introduced from the area surrounding the kurgans, e.g. weeds, halophytes, meadow species, as well as trees which are rarely found in the desert steppe zone. In spite of the small size of the kurgans, significant differences between the floristic composition of the various microhabitats were detected.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.