Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 24

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

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, dominance structure, and phenology of bees (Apiformes) was studied in the Białowiea National Park, which is a part of the most extensive primeval forest on the European Plain, the Białowiea Forest (NE Poland). In total 146 species of Apiformes are reported from the park. Beside the more or less abundant honey bees, the major bee species is Bombus lucorum, accounting for about 30% of wild bees and as much as 71.5% of bumblebees recorded there. Among 3 other bee species dominating in a large part of Poland, Bombus pascuorum accounts for nearly 11% of bumblebees, while B. terrestris and B. lapidarius are accessory species in the park. This shows approximately how the bee fauna looked like in most parts of Poland and Central Europe before human activity started to change the landscape radically, starting from the Middle Ages.
Białowieża Forest is the best preserved piece of mixed deciduous forest on European lowland. Owing to large number of old trees and large amounts of dead wood this forest became the refuge for arboreal and xylophilous organisms. In this paper 26 particularly interesting species of lichens and lichenicolous fungi are presented. Nine of these species are very rare in Poland and seven of them are new to Białowieża Forest: Lecanora compallens, Lichenomphalia umbellifera, Pachyphiale fagicola, Phaeosporobolus usneae, Rinodina degeliana, Trapelia corticola and Vouauxiella lichenicola.
Wild boars are omnivorous, their diet consists mainly of plants, and especially their bulbs, rhizomes, seeds fruits. Fungi, invertebrates and carcasses of animals are also part of diet, depending on a season. In search for food wild boars tear away the vegetation cover, aerating soil and mixing it with plant litter. Activities of these animals strongly influence plants, flora and vegetation. Out of natural geographic range, wild boar is recognized as a factor causing disturbances, destroying native plants and affecting the conservation status of species. Research on the activity of wild boars within their natural range focuses mainly on the role of this species in functioning of forest and agricultural ecosystems. There are up to date only a few research on the role played by wild boar in seed dispersal and none on their role in formation of soil seed banks.
Our research was conducted on abandoned fields which had been undergoing spontaneous succession for 40–50 years and then were partly burnt. The main objective of the study was to examine if spontaneous fire in the early successional stage of pine forest causes a decrease in the number of species, diversity and density of seed banks, and an increase in the share of species forming long term persistent seed banks. Standing vegetation and soil seed banks were studied on 20 permanent plots on adjacent burnt and unburnt sites one and twelve years after spontaneous fire. One year after the fire the number of species in the seed banks of both areas was similar (11 and 12 species). In the burnt area the Shannon index and the floristical similarity between the seed bank and standing vegetation were lower, and seed density five times higher than in the unburnt area (15 691.5 m–2 vs.3426.5 m–2). This was mainly the effect of the high number of seedlings of Calluna vulgaris (L.) Hull and Spergula morisonii Boreau germinating from the burnt plots. Twelve years after the fire the number of species in both seed banks had increased little, but seed density in the burnt area (1742.5 m–2) had decreased 16 times, while that of the unburnt area had changed only slightly (2875.5 m–2). At the same time the Shannon index for the burnt area increased considerably, whereas for the unburnt one it did not change. Our study shows that the long-term persistent soil seed bank plays a fundamental role at the beginning of the post-fire regeneration of temperate coniferous forest vegetation. Germination of Calluna seedlings from the burnt soil seed banks in several times higher numbers than from unburnt soil seed banks may suggest that heat from the fire promotes a loss of dormancy in the heather seeds.
The riparian forests develop in river valleys. Because of their soils fertility about 90% of the area occupied by forests of this type in the past has been transformed into farmlands. We studied hydrological characteristics conducive for development of riparian forests vegetation in small lowland river valley. Our study revealed limited role of the flooding phenomena in formation of these forests: average duration time of flooding amounted to 10 days per year. Frequent and long−lasting floods inhibit regeneration of the riparian forests on ex−meadows and prolong dominance of non−forest vegetation in the area adjacent to river channel.
Thermophilous oak wood is the most species-rich forest habitat in the zone of mixed deciduous forests. A very limited amount of it has been saved in good condition. We investigated the principal hypothesis that the vegetation and seed banks, especially of the ancient forest species, are good indicators of habitat naturalness and its aptitude for restoration. Vegetation and seed bank sampling were carried out in fragments of forest with a known management and disturbance history over the past 80 years. We predicted that natural and anthropogenic transformations of tree stands would be significant factors shaping species composition and similarity of vegetation and seed banks. The closest similarity was observed between the seed banks of plots which were never logged. The least related to others was the seed bank of the logged site, whose soil was ploughed prior to tree replantation. The highest number of ancient forest species was recorded in the vegetation (33 species) and in the soil seed bank (21 species) of the least transformed patch of thermophilous oak forest. It was decreasing gradually with increase of the tree canopy cover on the research plots. Our results indicate also that the higher the coefficient of similarity between seed bank and vegetation, especially of the ancient forest species, the higher the forest’s naturalness. We conclude that restoration of thermophilous oak wood has the highest chances for success in patches with well preserved seed banks and vegetation.
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.